Article

Reproduction and life history in the Red-tailed Phascogale, Phascogale calura (Marsupialia: Dasyuridae): the adaptive-stress senescence hypothesis

Wiley
Journal of Zoology
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Abstract

A population of the red‐tailed phascogale ( Phascogale calura ), a marsupial with a restricted distribution, was studied during a three‐year period at a small reserve in the South‐Westem Wheatbelt of Western Australia. This species shows a life‐history pattern which is typical of many Antechinus species and is characterized by a synchronized winter mating period followed by a complete male post‐mating mortality. Mating occurs during a three‐week period in July. In the field, males live only 11.5 months while females may live up to 36 months. Females are monoestrous and polyovular and have eight teats which are usually all occupied by pouch young. The production of supernumerary young is common. Pregnant females become aggressive toward the males. To explain the semelparous life history in this species, an adaptive‐stress‐senescence hypothesis is proposed. As males enter the mating period they make major physiological adjustments which are beneficial to the success of mating. However, there may be a longer‐term cost, that of hormonally accelerated ageing and senescence, which is finally expressed in impairment of feedback control of adrenocortical function.

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... (Wood 1970), Phascogale spp. (Cuttle 1982;Bradley 1997) and Dasykaluta rosamondae (Woolley 1991)), are among a small number of mammals with an obligate semelparous life history (Lee et al. 1982); all males die at the end of their first breeding season. Typically, breeding in red-tailed phascogales is highly synchronised -restricted to 2-4 weeks each year (Bradley 1997) -and promiscuous (Foster 2008). ...
... (Cuttle 1982;Bradley 1997) and Dasykaluta rosamondae (Woolley 1991)), are among a small number of mammals with an obligate semelparous life history (Lee et al. 1982); all males die at the end of their first breeding season. Typically, breeding in red-tailed phascogales is highly synchronised -restricted to 2-4 weeks each year (Bradley 1997) -and promiscuous (Foster 2008). Sperm storage of up to 8 days is known to occur in red-tailed phascogales , and in other dasyurids (Taggart et al. 2003) for up to 16 days (Selwood and McCallum 1987;Taggart and Temple-Smith 1991;Shimmin et al. 2000). ...
... We calculated copulation date as the last day the male was known to be alive, fertilisation date as 28-30 days before birth (Bradley 1997;Foster et al. 2006) and birth date (with a ±5 day error) by measuring the pouch young against a growth curve in Foster et al. (2006). ...
Article
We present a case of extended sperm storage in a female red-tailed phascogale (Phascogale calura) during a trial reintroduction in 2022. Parentage reported by single nucleotide polymorphism genotyping revealed the father of one litter had died approximately 50 days before the litter was born. The recorded gestation period for red-tailed phascogales is 28–32 days. Our record indicates sperm storage and/or diapause of up to 15–27 days, at least double the previously recorded sperm storage duration in this species.
... The kenngoor (Phascogale calura; also known as the redtailed phascogale), is one of the many Australian terrestrial mammals that has faced dramatic distribution declines since European settlement (Burbidge et al. 2009). The kenngoor is a short-lived (11-36 months) small (~ 40-60 g), semi-arboreal, carnivorous, and nocturnal marsupial (Bradley 1997;Stannard et al. 2010). Once widespread across western and central Australia (Fig. 1), its distribution is now limited to south-west Western Australia, an area less than 1% of its former range . ...
... The kenngoor was previously widely distributed across much of Australia but since European occupation has become restricted to an extensively fragmented area that represents less than 1% of their former range . For a small species (< 60 g) with a short generation time (3 years ;Bradley 1997), there is a surprising lack of strong genetic differentiation given the habitat has been fragmented for ~ 75 years (Saunders 1989). We find that the species retains similar genetic diversity across the 13 highly fragmented reserve areas sampled, with little evidence of increased inbreeding or within location relatedness. ...
... While these sampling locations broadly represent the known geographic range, the species has been recorded in other patches not sampled here ). suggested kenngoor have the capacity to disperse across the landscape, citing their presence in patches smaller than the reported home range, community sightings in and around buildings , and evidence of movements up to 800 m over 24 h (Bradley 1997). Indeed, the Australian Wildlife Conservancy recently detected an individual at Paruna Wildlife Sanctuary, ~100 km from any known population (J. ...
Article
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Kenngoor (Phascogale calura) persist in < 1% of their original distribution, occupying highly fragmented remnant habitat in south-west Western Australia, with very little known of the genetic diversity of the remaining wild populations. Recently, the species has been translocated to managed reserves to improve its conservation. Understanding genetic structure and patterns of genetic diversity is crucial to inform conservation translocations for species recovery. This study aims to (1) assess genetic structure and genetic diversity across remaining wild locations, (2) assess long-term genetic outcomes of a mixed-source wild-to-wild translocation, and (3) estimate global effective population size. We genotyped 209 samples from 13 locations of fragmented remnant habitat using reduced representation sequencing. An isolation by distance model best explained genetic structure across the survey areas, with evidence of fine scale divergence of two northern locations. Allelic richness and autosomal heterozygosity measures indicated that diversity is spread uniformly across locations, and no locations showed signs of inbreeding or strong genetic drift. The mixed-source translocation has retained the diversity of the wider species ten years post-translocation. Overall, our results suggest that connectivity between survey areas has largely been maintained and that no location has substantially lower genetic diversity, despite the highly fragmented nature of remnant kenngoor habitat. Future translocations should aim to represent a mixture of genetically divergent locations to maintain the diversity present at the species level. Ongoing conservation management will be required to ensure the long-term viability of the species in this fragmented landscape.
... Females are mono-estrus, and give birth to young during July-August Lee et al., 1982;McAllan, 2003). Males die shortly after mating (Bradley, 1997). ...
... Males are introduced into the female's enclosure in early May to enable breeding. Pregnant females become aggressive towards males (Bradley, 1997;personal observations), thus males should be removed once mating has been confirmed or aggression observed. ...
... Phascogale young are born after a 28-30 day gestation (Bradley, 1997). Females give birth to supernumerary young (up to 13), however, they can only accommodate a maximum of eight young in the pouch (Bradley, 1997). ...
Article
There are many limitations when using traditional laboratory species. Limits on variation, may result in limited outcomes, at both the species and individual level, due to different individuals/species having diverse physiological processes, or differing molecular and genetic mechanisms. By using a variety of model species, we will be able to develop creative solutions to biological problems and identify differences of which we were not previously aware. The laboratory mouse has been a suitable model species for various mammalian studies, however most are bred specifically for laboratory research with limited variability due to selective breeding. Marsupial models offer unique research opportunities compared to eutherian models. We believe that there should be an expansion in marsupial model species, and the introduction of the red‐tailed phascogale (Phascogale calura), a dasyurid marsupial, should be one of them. Phascogales are easily managed in captivity, and there are now multiple studies involving their development, reproduction, nutrition, behavior and immune system, which can serve as a baseline for future studies. The addition of the phascogale as a model species will improve future mammalian studies by introducing variability and offer alternate solutions to biological problems, particularly in the areas of genetics, nutrition, immunology, the neuro‐endocrine system, and ageing, due to their semelparous reproductive strategy and hence, subsequent predictive physiology. In this review, we provide information based on existing research on red‐tailed phascogales to support their inclusion as a model species. Highlights • Traditional laboratory species are limited in variation, hence can limit scientific outcomes. • Red‐tailed phascogales are semelparous and easily managed in captivity. • They offer an alternative animal model to investigate biological problems.
... The red-tailed phascogale (Phascogale calura) is a small Australian dasyurid marsupial. Males are semelparous; they die off after a short, highly synchronous breeding season at around 11.5 months of age, while females can breed once a year for two to three years [1,2]. The total mortality of red-tailed phascogale males has been shown to be stress-related [1], as reported for other semelparous dasyuridsthe brush-tailed phascogale (Phascogale tapoatafa) [3] and several Antechinus species [4][5][6]. ...
... The total mortality of red-tailed phascogale males has been shown to be stress-related [1], as reported for other semelparous dasyuridsthe brush-tailed phascogale (Phascogale tapoatafa) [3] and several Antechinus species [4][5][6]. The dasyurid breeding season is characterized by an extremely intense level of sexual activity and aggressive interactions [2,7]. Although Barnett [8] was unable to demonstrate accelerated aging of brown antechinus (Antechinus stuartii) males compared to females of the same chronological age, Bradley [2] suggested an "adaptive stress-senescence hypothesis". ...
... The dasyurid breeding season is characterized by an extremely intense level of sexual activity and aggressive interactions [2,7]. Although Barnett [8] was unable to demonstrate accelerated aging of brown antechinus (Antechinus stuartii) males compared to females of the same chronological age, Bradley [2] suggested an "adaptive stress-senescence hypothesis". He proposed that males make major physiological adjustments to increase the success of mating, possibly at the longer-term cost of hormonally accelerated aging and senescence. ...
Article
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Background The red-tailed phascogale is a ‘Near Threatened’ dasyurid marsupial. Males are semelparous and die off shortly after the breeding season in the wild due to a stress-related syndrome, which has many physiological and immunological repercussions. In captivity, males survive for more than 2 years but become infertile after their first breeding season. Meanwhile, females can breed for many years. This suggests that captive males develop similar endocrine changes as their wild counterparts and undergo accelerated aging. However, this remains to be confirmed. The health status and immune function of this species in captivity have also yet to be characterized. Results Through an integrative approach combining post-mortem examinations, blood biochemical and hematological analyses, we investigated the physiological and health status of captive phascogales before, during, and after the breeding season. Adult males showed only mild lesions compatible with an endocrine disorder. Both sexes globally maintained a good body condition throughout their lives, most likely due to a high quality diet. However, biochemistry changes potentially compatible with an early onset of renal or hepatic insufficiency were detected in older individuals. Masses and possible hypocalcemia were observed anecdotally in old females. With this increased knowledge of the physiological status of captive phascogales, interpretation of their immune profile at different age stages was then attempted. During the breeding season, males developed a stress leukogram characterized by a marked lymphopenia, further aggravated by a severe leukopenia after the breeding season. To determine whether these changes were limited to the peripheral blood or had more profound implications, histopathology of the spleen was performed opportunistically. Adult males showed white pulp atrophy, at various degrees. The atrophy was mainly lymphoid and more severe in 1.5-year-old males than in 3.5-year-old females. These results suggest that captive males undergo accelerated immunosenescence. Conclusions Functional studies are now needed to characterize the underlying mechanisms leading to immunosenescence in marsupials. Semelparous dasyurids present great potential for studying the effects of sex and stress on immunity in marsupials. Characterization of these immune-endocrine interactions may help refine veterinary treatment plans, husbandry protocols and conservation programs to maintain the health of captive and wild populations.
... Its range formerly covered much of semiarid and arid Australia but it now persists only in the southern Western Australian wheatbelt occupying less than 1% of its former range (Short and Hide 2012), with the core of this remaining range lying between Brookton and Katanning ( Fig. 1). Aspects of its ecology and habitat preferences in the Western Australian wheatbelt have been detailed by Kitchener (1981), Bradley (1997) and Short et al. (2011). Factors linked to its decline include fragmentation of habitat by clearing for agriculture, particularly of woodland habitats rich in suitable nesting hollows, and predation by feral and domestic cats and by foxes (Short and Hide 2012). ...
... The species' life history is characterised by a short, synchronised annual mating period in winter followed by the death of all males (Bradley 1997). This reproductive strategy is believed to put the species at risk of reproductive failure in any given yeara possibility believed more likely in arid and semiarid sites where populations may be sparse or climate unpredictable (Kitchener 1981;Foster et al. 2006). ...
... Males released at Wadderin in April 2009 persisted no longer than three months after release. This is consistent with what is known of the biology of the species, with males exhibiting postmating mortality and living for only 11.5 months (Bradley 1997). In contrast, five of the 12 females released into the sanctuary were detected in late autumn and winter 2010 and another at the end of the breeding season in December 2010. ...
Article
Red-tailed phascogales (Phascogale calura) were reintroduced to Wadderin Sanctuary in the eastern wheatbelt of Western Australia in April 2009 with individuals sourced from remnant native vegetation on farmland some 180km to the west. Their establishment was monitored initially by radio-telemetry and trapping, and subsequently by the checking of nest boxes both within and outside the sanctuary. Translocated phascogales established well and bred successfully in their first season. Phascogales remain extant at Wadderin more than five years after release and appear to be abundant and to occupy all available habitat. They have spread beyond the fenced sanctuary to adjoining woodland and to shrubland and woodland habitat in a remnant 1.4km away. Comparison with two other reintroductions of this species (one apparently successful, one not) suggests management and habitat factors that may have contributed to the outcomes.
... It inhabits a small area of south-west Western Australia and is listed as endangered [30]. The red-tailed phascogale is a monoestrus breeder with a very short (3 week) synchronised breeding season [31,32]. Females give birth to supernumerary young after a 28 day gestation, but can only accommodate eight young in the pouch [32]. ...
... The red-tailed phascogale is a monoestrus breeder with a very short (3 week) synchronised breeding season [31,32]. Females give birth to supernumerary young after a 28 day gestation, but can only accommodate eight young in the pouch [32]. Young are fixed to the nipple for 44 days and are weaned at 90-110 days [33]. ...
... Young are fixed to the nipple for 44 days and are weaned at 90-110 days [33]. Males exhibit semelparity in the wild and can live longer in captivity but are infertile after 11.5 months [32]. ...
... As eutherian mammals have an established complement system (Sarma and Ward 2011), we would expect that metatherian mammals (the marsupials) also possess a complement system as part of their immune portfolio. Previously, haemolytic assays performed on the serum of two marsupials, the Virginian opossum (Didelphis virginiana; (Wirtz and Westfall 1967)) and the gray short-tailed opossum (Croix et al. 1989;Koppenheffer et al. 1998), suggest that there is a functional complement system in members of the opossum family, but there have been no other studies investigating complement activation in other species of marsupials using this method, a method that is a routine for the clinical assessment of complement in humans and other eutherian mammals (Bradley 1997). Investigations of the presence and function of a complement system in marsupials is important as it could be the key to understanding the mechanism of immune protection of pouch young (Joss et al. 2007). ...
... RTPs are small nocturnal dasyurid marsupials (family Dasyuridae) (Bradley 1997) with populations restricted to the southwest of Western Australia (Berden et al. 1978;Kitchener 1981). The complexity of the marsupial immune system, along with the population decline of most dasyurid species since European settlement, enhances the importance of the RTP as a model species for this study. ...
... Evidence for a complement system in eutherian mammals can be determined using haemolytic complement assays. These assays are conducted using serum as a source of complement together with unsensitised rabbit erythrocyte (RbE) and sensitised sheep erythrocytes (SE) as indicator cells (Bradley 1997). The lysis of unsensitised RbE and sensitised SE when exposed to dasyurid serum will confirm the presence of a classical and alternative complement pathway, respectively, in this species and enhance our capacity to investigate fundamental immunity in dasyurid mammals. ...
Article
Very few assays that are used to assess the status of mammalian immunity have proved useful for assessment of marsupial health and/or diagnosis of disease. This is largely due to the lack of species cross-reactive reagents that underpin such experiments. To begin to address this deficit, we describe the activation of classical and alternative complement pathways of red-tailed phascogales (RTP; Phascogale calura). Using standard haemolytic assays, the existence of both complement pathways were established in RTP serum based on its ability to lyse unsensitised rabbit erythrocytes (RbE) and sensitised sheep erythrocytes (SE), respectively. The alternative complement pathway assays were conducted using pooled serum of male and female RTPs, and the remaining RTP sera were opportunistically used to test the presence of a functional classical complement system in individual animals, a first in non-eutherian animals. Observations from this study suggest that the activation of these two complement pathways in RTPs are comparable to that seen in other mammals. Since this assay was able to be used on very small samples of blood, it could serve as a useful tool to gather data for comparative immunological studies and to further our knowledge of the mechanisms of immunity available to marsupial young.
... Semelparity can be seen as an extreme form of investment into a single reproductive attempt to the detriment of all future breeding attempts. This obligate semelparity is seen in plants, invertebrates and fish, but is rare in mammals (Braithwaite and Lee 1979), where it is only seen in Antechinus (Wood 1970;Woolley 1966), Phascogale (Bradley 1997;Cuttle 1982) and Dasykaluta rosamondae (Woolley 1991a). ...
... The red-tailed phascogale, Phascogale calura, is a species that was not included in the original description of dasyurid life history strategies by Lee et al. (1982). Field work conducted with populations in Western Australia found that males were semelparous, dying shortly after a ~ 3 week breeding period, although the females survived for multiple breeding seasons (Bradley 1997). The breeding season occurred during July and was followed by a gestation period of ~30 days (Bradley 1997). ...
... Field work conducted with populations in Western Australia found that males were semelparous, dying shortly after a ~ 3 week breeding period, although the females survived for multiple breeding seasons (Bradley 1997). The breeding season occurred during July and was followed by a gestation period of ~30 days (Bradley 1997). ...
Article
Who's Your Daddy? Over the last year, there has been some action happening quietly behind the doors of the Animal Health and Research Centre, and I'm not referring to the treatment of sick animals. I'm talking about sex, and lots of it! This is the six-hour continuous lovemaking that has you hanging from the roof kind of sex. The new partner every day kind of sex. The make love til you drop kind of sex. What! I hear you exclaim. That's outrageous! Well before you get too outraged maybe I should clarify a couple of things. The individuals involved in this rampant love-making are an endangered carnivorous marsupial known as the red-tailed phascogale. This species was once found over large regions of Australia, but is now only found in south-west WA, where they are rarely seen due to their small size and their tree-top antics occurring at night. As I alluded to above, their sex-life is not for the fainthearted. They only breed once a year with mating occurring over a few weeks in winter – maybe close body contact makes cold days easier to bear. Both males and females have multiple partners, which can result in a litter of young having multiple fathers – so it really is a question of 'who's your daddy?' At the end of those several weeks of frenzied sex, the males escape any parental duties by dying. Ah, the life of a male – live off mum for a quarter of your life, go out wandering the world for half your life while building up those muscles, then pick fights with any other bloke you meet, chase the girls and have sex as much as possible for the last quarter.
... Loss of habitat and increasing isolation of remaining habitat patches are key forces affecting the fate of fauna worldwide (Diamond 1989;Andrén 1994;Fischer and Lindenmayer 2007). With fauna confined to ever smaller habitat patches, stochastic influences become more important (Lande 1998), and this may be particularly so for species such as the red-tailed phascogale (Phascogale calura), which has a life history characterised by a complete annual male die-off at the end of the first year of life (Cuttle 1982;Bradley 1997). ...
... Trapping was largely limited to woodland associations, as previous trapping in adjacent habitats in wheatbelt remnants (e.g. heath, laterite ridges) had shown few or no captures (Kitchener and Chapman 1978;Bradley 1997). plus symbols are sites that were trapped but where no phascogales were caught. ...
... Red-tailed phascogales appear to move widely around the landscape, particularly in areas where linking corridors of vegetation remain. Evidence for such movements included community sightings, often in and around buildings that were distant from substantial patches of remnant vegetation (Short and Hide in press), the presence of phascogales in small remnants with an area less than that recorded for home range suggesting they utilise multiple patches or travel between patches, and evidence from radio-telemetry and trapping studies of substantial short-term movements (e.g. a male moved 800 m between captures on successive nights: Bradley 1997). However, as distances increased beyond about five kilometres from another occupied remnant the likelihood of establishment or re-colonisation seemed to decline. ...
Article
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Context The red-tailed phascogale once occurred widely across semiarid and arid Australia, but is now confined to the southern wheatbelt of Western Australia. Its apparently extensive former range suggests a broad habitat tolerance, yet it is now reported primarily from remnant vegetation within farmland containing wandoo Eucalyptus wandoo and rock sheoak Allocasuarina huegeliana associations. Aims To establish the habitat requirements of phascogales with a view to understanding their current and likely future distribution and status. Methods We established presence or absence of phascogales at a number of sites within their current range, primarily by trapping, and then compared habitat attributes between the two classes of sites to establish those of apparent significance to species persistence. Key results Phascogales are widespread in suitable upland (wandoo–rock sheoak) and lowland habitat (riverine fringing vegetation of swamp sheoak Casuarina obesa, York gum E. loxophleba and wandoo). They occupy areas of remnant vegetation of varying sizes from very small to very large, many on private agricultural land. Large connected areas, such as riverine corridors and clusters of upland remnants appear important to their long-term persistence. Sites isolated by increasing distance from another occupied site tended to be unoccupied. Habitats occupied by phascogales typically had a greater canopy density and greater abundance of hollows than unoccupied sites. The presence of plants of the genus Gastrolobium, often cited as a key factor in the persistence of phascogales, did not appear to influence the presence or absence of phascogales. Conclusions Red-tailed phascogales currently occupy a broader range of habitats than identified in the literature and the role of some key aspects of habitat in protecting them from further decline may have been overstated. The presence of suitable hollows for nesting and shelter and a dense mid-storey canopy, perhaps to protect from predation by owls, are key features of suitable phascogale habitat. Implications Suitable habitat for phascogales appears widespread in the surveyed portion of the remaining range of the species, but is under threat over the longer term. Increasing salinity in lowland areas (which transforms woodland to samphire with a consequent long-term loss of nesting hollows), lack of fire in upland areas to maintain dense stands of rock sheoak and the increasing loss of corridors of vegetation along roadsides due to the widening of roads by local councils are all contributing to loss of habitat and habitat connectivity.
... The red-tailed phascogale is a semelparous breeder, meaning there is an annual die-off of males after the breeding season and a low proportion of females that survive to a second year [24]. This annual die-off increases the risk of non-establishment of a new population, particularly with a small number of founders. ...
... This annual die-off increases the risk of non-establishment of a new population, particularly with a small number of founders. Implementing a breeding program has the potential to maximise the contribution of wild-caught individuals for species recovery by facilitating successful breeding and rearing of the high number of young produced per female (up to eight) and has the potential to provide individuals for supplemental releases if needed [24]. ...
Article
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The application of genetic data to conservation management programs can be hindered by the mismatch in timelines for management decisions and the acquisition of genetic data, particularly genomic sequence data that may require outsourcing. While applying genetic principles where data are absent can provide general guidelines for actions, genetic data can often fine-tune actions through adaptive management. We describe the adaptive genetic management of the establishment of a metapopulation of a small arboreal marsupial, the red-tailed phascogale (Phascogale calura). Two captive breeding programs were established as source populations, with genetic principles applied to the establishment of the first program and empirical genetic data used to guide the establishment of the second program. Genetic data from both programs were then used to allocate founders to three new populations to create a metapopulation with diversity both within and among the sites. Building and maintaining the diversity of metapopulations when recovering threatened species will reduce pressure on the original source populations and increase the resilience of the species.
... They are listed as 'near threatened' by IUCN (NT: C1 + 2a(i); Friend, 2008). Males are semelparous, whilst females have been recorded to live up to five years in captivity and can breed in multiple years (Bradley, 1997;Stannard et al., 2013). Kultarrs are small carnivorous marsupials and weigh 20-45 g (Valente, 2008;Stannard & Old, 2011a, b, 2014. ...
... Age and optimal frequency association, as well as the age and frequency at 60 dB, were investigated to determine if age was significant at a higher dB SPL than at optimal hearing. Presbycusis is a potential variable with phascogale males that in the wild would have died at the age of 11.5 months (Bradley, 1997;Stannard et al., 2013). Extended life-expectancy in captivity may, therefore, significantly impact the hearing of male phascogales, as observed in one male in this study, but this did not occur in all individuals in this species. ...
Article
Hearing is essential for communication, to locate prey and to avoid predators. We addressed the paucity of information regarding hearing in Australian native mammals by specifically assessing the hearing range and sensitivity of the red-tailed phascogale (Phascogale calura), the kultarr (Antechinomys laniger) and the spinifex hopping-mouse (Notomys alexis). Auditory brainstem response (ABR) audiograms were used to estimate hearing thresholds within the range of 1–84 kHz, over a dynamic range of 0–80 dB sound pressure level (SPL). Phascogales had a hearing range of 1–40 kHz, kultarrs 1–35 kHz and hopping-mice 1–35 kHz, with a dynamic range of 17–59 dB SPL, 20–80 dB SPL and 30–73 dB SPL, respectively. Hearing for all species was most sensitive at 8 kHz. Age showed no influence on optimal hearing, but younger animals had more diverse optimal hearing frequencies. There was a relationship between males and their optimal hearing frequency, and greater interaural distances of individual males may be related to optimal hearing frequency. Because nocturnal animals use high-range hearing for prey or predator detection, our study suggests this may also be the case for the species examined in this study. Future studies should investigate their vocalizations and behaviour in their natural environments, and by exposing them to different auditory stimuli.
... No other tetrapod species, including short-lived marsupials (11,12,17,33) and lizards, are known to have a life history similar to that of F. labordi. Previous reviews of other lizards (20,21,34) report 11 species as putatively annual. ...
... Indeed, F. labordi is characterized by physically intense combat and agonistic courtship (unpublished data). A similar mode of evolutionary selection appears to have played a role in the evolution of semelparity in at least one other tetrapod, the marsupial Phascogale calura (33). Accounting for hormonal regulation of physiology and behavior is critical to a comprehensive understanding of life history evolution (1,42). ...
Article
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The ≈28,300 species of tetrapods (four-limbed vertebrates) almost exclusively have perennial life spans. Here, we report the discovery of a remarkable annual tetrapod from the arid southwest of Madagascar: the chameleon Furcifer labordi, with a posthatching life span of just 4–5 months. At the start of the active season (November), an age cohort of hatchlings emerges; larger juveniles or adults are not present. These hatchlings grow rapidly, reach sexual maturity in less than 2 months, and reproduce in January–February. After reproduction, senescence appears, and the active season concludes with population-wide adult death. Consequently, during the dry season, the entire population is represented by developing eggs that incubate for 8–9 months before synchronously hatching at the onset of the following rainy season. Remarkably, this chameleon spends more of its short annual life cycle inside the egg than outside of it. Our review of tetrapod longevity (>1,700 species) finds no others with such a short life span. These findings suggest that the notorious rapid death of chameleons in captivity may, for some species, actually represent the natural adult life span. Consequently, a new appraisal may be warranted concerning the viability of chameleon breeding programs, which could have special significance for species of conservation concern. Additionally, because F. labordi is closely related to other perennial species, this chameleon group may prove also to be especially well suited for comparative studies that focus on life history evolution and the ecological, genetic, and/or hormonal determinants of aging, longevity, and senescence. • Madagascar • lizard • longevity • semelparity • senescence
... The semelparous life history of phascogale, where males die off each year at the end of the breeding season (Bradley 1987(Bradley , 1997, may increase the susceptibility of this species to decline (Kitchener 1981;Foster et al. 2006). In addition, a substantial number of females apparently die after weaning their first litter (Bradley 1987). ...
... Female red-tailed phascogale have home ranges averaging between 1.4 and 8.7 ha, while males have ranges that may exceed 80 ha during the breeding season (Friend and Friend 1993). Movements of males of up to 1 km during the breeding season were recorded, including one movement of 800 m within a 24-h period (Friend and Friend 1993;Bradley 1997). Brush-tailed phascogale have been detected crossing gaps of 225 m to nest trees: (van der Ree et al. 2006). ...
Article
The red-tailed phascogale once extended widely across semiarid and arid Australia, but is now entirely confined to the southern wheatbelt of Western Australia, occupying less than 1% of its former range. Here it occurs in a portion of the Avon Wheatbelt, Jarrah Forest, Malice, and Esperance Plains biogeographical regions. The species persists only in areas that have been extensively cleared for agriculture and where the remaining bushland is highly fragmented. It does not appear to extend into unfragmented habitat in either the Jarrah Forest to the west or Malice region to the east, It occurs primarily in woodland habitat with old-growth hollow-producing eucalypts, primarily wandoo (Eucalyptus wandoo) or York Gum (E. loxophleba), but records from the periphery of its current range appear to come from a broader range of habitats, including shrublands and various mosaics of woodland, shrubland, and scrub-heath. Key factors limiting persistence are likely to be fragmentation of habitat that is likely to greatly increase the risks associated with dispersal, a shortage of suitable nesting hollows in many vegetation associations, and predation by feral and domestic cats and by foxes. These factors, particularly fragmentation and lack of suitable nesting hollows, suggest that the species' long-term persistence in areas beyond the wandoo belt is far from assured.
... Scent glands have been described in 15 of the 19 orders of mammals (Thiessen and Rice 1976). Within the Metatheria, scent glands have been identified in the sugar glider Petaurus breviceps (Stoddart and Bradley 1991), Phascogale calura (Bradley 1997), and grey short-tailed opossum Monodelphis domestica (Fadem and Schwartz 1986, Fadem et al. 1989, Fadem 1990). Several different forms of scent marking behaviour have been reported in dasyurids (Table 2). ...
... As far as we are aware, the presence on the hair surface of specialisations for holding material that may provide chemical signals in social communication has not been described in dasyurid marsupials. Bradley (1997) has discussed the apparent importance of the sternal gland and its secretions in Phascogale calura in which the sternal gland of males becomes very active when the plasma testosterone concentration rises during the breeding period. In ovariectomised females of another marsupial species the grey short-tailed opossum Monodelphis domestica the development of suprasternal glands and chest marking may be stimulated by testosterone administration but not by oestradiol (Fadem 1990). ...
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This chapter gives a brief overview of studies that have been carried out to describe the way in which dasy-urid marsupials communicate by chemical means. This involves the production of chemical substances from both cutaneous scent glands and glands associated with the reproductive tract, the dispersal of these sub-stances by various morphological adaptations, and the detection of these airborne chemicals (pheromones) by the special sensory system, the vomeronasal organ (VNO). Gas chromatography coupled with mass spectroscopy GC-MS is increasingly being applied to identify substances used by animals in chemical com-munication. While many of the structures used by animals to detect pheromones have been known for many years, it is only now with the availability of sensitive techniques such as functional magnetic resonance imaging (fMRI) that we are able to visualise regional changes in brain activity in temporal sequence in response to these pheromones.
... However, Mn competes for Fe binding sites, thus decreasing Fe absorption and ultimately causing anemia (Aschner et al., 2007). Because anemia is also characteristic of postbreeding physiology among other dasyurids (Bradley, 1987(Bradley, , 1997Lee & Cockburn, 1985;McDonald et al., 1986), interactions between Mn exposure and breeding physiology on the development of anemia and impairment of immune function warrants further investigation. ...
Article
Reproductive costs must be balanced with survival to maximise lifetime reproductive rates; however, some organisms invest in a single, suicidal bout of breeding known as semelparity. The northern quoll ( Dasyurus hallucatus ) is an endangered marsupial in which males, but not females, are semelparous. Northern quolls living near mining sites on Groote Eylandt, Northern Territory, Australia, accumulate manganese (Mn) in their brains, testes, and hair, and elevated Mn impacts motor performance. Whether Mn is associated with other health declines is yet unknown. Here, we show that male and female northern quolls with higher Mn accumulation had a 20% reduction in immune function and a trend toward reduced cortisol concentrations in hair. The telomere lengths of male quolls did not change pre‐ to post‐breeding, but those with higher Mn levels had longer telomeres; in contrast, the telomeres of females shortened during the breeding season but recovered between the first year and second year of breeding. In addition, the telomeres of quolls that were re‐captured declined at significantly higher rates in quolls with higher Mn between pre‐breeding, breeding, and/or post‐breeding seasons. Future work should determine whether changes in cortisol, immune function, or telomere length affect reproductive output or survival—particularly for semelparous males.
... Inbreeding may be unavoidable in small populations, with the increased homozygosity of deleterious alleles leading to reduced tness (Frankham, 2005), and decreased genetic diversity resulting in lowered adaptive capacity The kenngoor (Phascogale calura; also known as the red-tailed phascogale), is one of the many Australian terrestrial mammals that has faced dramatic distribution declines since European settlement (Burbidge et al., 2009). The kenngoor is a short-lived critical weight-range (~ 40-60g), semi-arboreal, carnivorous, and nocturnal marsupial (Bradley, 1997;Stannard et al., 2010). Once widespread throughout Australia (Fig. 1), its distribution is now limited to south-west Western Australia, an area less than 1% of its former range . ...
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Kenngoor ( Phascogale calura ) persist in < 1% of their original distribution, occupying highly fragmented remnant habitat in south-west Western Australia, with very little known of the genetic health of remaining wild populations. Recently, the species has been translocated to managed reserves to improve its conservation. Understanding genetic structure and patterns of genetic diversity is crucial to inform conservation translocations for species recovery. This study aims to 1) assess genetic structure and genetic diversity across remaining wild populations, 2) assess long-term genetic outcomes of a mixed-source wild-to-wild translocation, and 3) estimate global effective population size. We sequenced 209 samples from 13 fragmented wild populations were sequenced using reduced representation sequencing. An isolation by distance model best explained genetic structure across the wild populations, with evidence of fine scale divergence of two northern populations. Allelic richness and autosomal heterozygosity measures indicated that diversity is spread uniformly across populations, and no populations showed signs of inbreeding or strong genetic drift. The mixed-source translocation has retained the diversity of the wider species ten years post-translocation. Overall, our results suggest that connectivity between wild populations has largely been maintained and that no population is in poorer genetic health, despite the highly fragmented nature of remnant kenngoor habitat. Future translocations should aim to represent a mixture of genetically divergent populations to maintain the diversity present at the species level. Ongoing conservation management will be required to ensure the long-term viability of the species in this fragmented landscape.
... In antechinuses (Woolley 1966, and many others) and phascogales (Bradley 1997; reviewed in , Cockburn 1997, individuals reach sexual maturity at 11 months of age and have a single, highly synchronised and short mating season each year (mainly in winter), after which all males die from physiological stress (semelparity; (Mills & Bencini 2000) and northern quolls (Oakwood et al 2000), some males survive to breed in a second reproductive event and not all females become pregnant during the breeding season (~65-88%, Begg 1981) producing litters of four to ten young and some of them will even survive to breed in a third year, but not very successfully (Morton et al 1989). In other species of dasyurids like the eastern and tiger quolls, Tasmanian devils and the crest-tailed mulgara (Woolley 1971, Settle 1978, Godsell 1982, ...
... All traps were checked each morning for three consecutive days before collection. In March and April, phascogales are close to full adult size, but mating and male die-off have not yet occurred, so males are present and no females have pouch young (Bradley 1997). Repeat trapping of individuals is common, so trapping is not conducted for longer than three consecutive nights because of welfare concerns. ...
Article
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Context Feral cats have benefitted from effective control of foxes in south-western Australia and, consequently, their impact on some threatened mammal species has increased. Control of feral cats in the region can be enhanced by use of the Eradicat® cat bait, but its impact on non-target animal populations requires investigation before widespread use. Aims The aim of the present study was to determine through field trials whether consumption of Eradicat® baits by resident red-tailed phascogales, following a broadscale baiting operation to control feral cats, was sufficiently frequent to cause significant rates of mortality in wild populations of phascogales. Methods Nine radio-tagged red-tailed phascogales were monitored through an Eradicat® baiting event to determine their survival. Removal and consumption of toxic and non-toxic rhodamine B-labelled baits by a range of species were monitored with camera traps and by subsequent trapping of red-tailed phascogales and other mammals to sample whiskers for evidence of rhodamine uptake. Key results Although some phascogales showed interest in baits and sometimes moved them from the deposition site, all radio-tagged phascogales survived for at least 1 week after baiting, by which time very few or no baits remained. Examination of whiskers sampled from individuals exposed to rhodamine-labelled baits showed that consumption of non-toxic Eradicat® baits by phascogales was negligible; only one phascogale of 62 sampled showed any rhodamine banding. Conclusions The present study provided no evidence that red-tailed phascogales in the study region are at risk from an Eradicat® baiting episode in autumn. Implications The risk to red-tailed phascogale populations through the use of Eradicat® baiting to control cats in their habitat in the Great Southern region of Western Australia is likely to be low. Further research to elucidate any impact of repeated baiting on populations of this species at several locations is recommended.
... The life history of red-tailed phascogales has been described by Bradley (1997). Females (32.6 ± 0.9 g) are smaller than males (47.2 ± 2.7 g). ...
... The red-tailed phascogale is a small, arboreal, predominately insectivorous (Bradley, 1997;Stannard et al., 2010), Australian native marsupial within the Dasyuridae family, which also includes the Tasmanian devil and quolls (Dasyurus spp.). The red-tailed phascogale and many other Dasyurid species are classified as endangered. ...
Article
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Cells expressing the surface markers CD3, CD4, CD79b, IgM, MHC class II, and ModoUG (nonclassical MHC class I) were detected in red‐tailed phascogale tissues using immunohistochemistry, and the appearance and localization of cells observed here was consistent with previous observations in other marsupial species. CD3⁺ cells were first detected at one day postpartum (dpp) in the thymus, followed by ModoUG⁺ cells at 5–7 dpp in the thymus and lymph nodes. CD79b⁺ cells were first detected at 12–14 dpp in bone marrow, spleen, and lymph nodes. IgM⁺ cells were first detected at 12–14 dpp in thymus, bone marrow, spleen, and lymph nodes. MHC class II⁺ cells were first detected at 12–14 dpp in thymus, bone marrow, and lymph nodes. CD4⁺ cells were detected in adult thymus and spleen only. The presence of the mature immune cell populations and their localization to characteristic T and B cell zones in mature lymphoid tissues with normal histological structure indicates that red‐tailed phascogales develop immunocompetence by the end of pouch life. Anat Rec, 302:1985–2002, 2019. © 2019 American Association for Anatomy
... The red-tailed phascogale (Phascogale calura) is a small, Australian native species from the family Dasyuridae, is predominately insectivorous (Bradley, 1997;Stannard et al., 2010) and breeds well in captivity (Foster et al., 2008;Stannard et al., 2013). Previous immunological investigations of this species include histological examination of the lymphoid tissues, both in developing pouch young and juveniles and adults (Old et al., 2006). ...
... Red-tailed phascogales are small arboreal, carnivorous marsupials found in Western Australia (Bradley, 1997), and are model marsupials for scientific research because they are easily kept in captivity (Stannard et al., 2013) and breed annually in July (Bradley, 1987;Foster et al., 2008). The data reported here helps in establishing the role of complement prior to the development of an adaptive immune system in young marsupials, a role that has not been previously investigated. ...
Article
Marsupials are born immunologically premature, relying on cells and molecules in maternal milk for immune protection. Both immunoglobulin and complement proteins have been identified in marsupial milk, but the expression of specific complement proteins remains largely unexplored. We report partial cDNA sequences for two complement-activating proteins, C3, C1r, CFP and MASP2, in liver tissues from red-tailed phascogale (Phascogale calura). Conservation of functionally relevant motifs were identified in the translated cDNA sequences from phascogale C3, CFP and MASP2 and their eutherian homologues. Gene expression of representative molecules from each of the major complement pathways was also investigated in whole body tissues from 1 to 18 day old animals and liver tissues from 31-day to 14-month old animals. Average complement expression in whole bodies and liver tissues of C1r, CFP, MASP2 and C3 increased significantly in juveniles compared to pouch young, presumably due to the maturation of the young's own complement system. Comparing expression in liver tissues only, we found that the average CFP expression were higher in pouch young compared to juveniles, while results were still statistically similar to the average expression of all tissues for C1r, MASP2 and C3. The average complement expression then significantly decreased as the animals aged into adulthood.
... However, both this species and its congener, the red-tailed phascogale (P. calura), were formerly distributed in far more arid areas (Baynes 1987;Bradley 1997), where rainfall is both low and unreliable. Given the seeming importance of food limitation in the jarrah forest, and its apparent relationship with drought, the occurrence of the brush-tailed phascogale in areas such as the Nullarbor Plain (Baynes 1987) presents a paradox. ...
Article
The Australian Brush-tailed Phascogale (Phascogale tapoatafa sensu lato) has a broad but highly fragmented distribution around the periphery of the Australian continent and all populations are under significant ongoing threat to survival. A new appraisal of morphological and molecular diversity within the group reveals that the population in the ‘Top End’ of the Northern Territory is specifically distinct from all others, including those in the Kimberley region of Western Australia to the west and on Cape York of Queensland to the east. The name P. pirata Thomas, 1904 is available for the ‘Top End’ taxon. Three geographically disjunct populations are distinguished at subspecies level within P. tapoatafa on a suite of external and cranio-dental features; these are found in southeast Australia from South Australia to mid-coastal Queensland (nominotypical tapoatafa), southwest Western Australia (wambenger subsp. nov.), and the Kimberley region of Western Australia (kimberleyensis subsp. nov.). A potential fourth subspecies occurs on Cape York but remains too poorly represented in collections for adequate characterization. Molecular divergence estimates based on partial sequences of the mitochondrial cytochrome b gene indicate that the range disjunction across southern Australia probably dates from the Late Pliocene, with the multiple disjunctions across northern Australia being more recent though almost certainly exceeding 400,000 years. An argument is made for the continued use of the subspecies rank in Australian mammalogy, despite a general lack of consistency in its current application.
... The red-tailed phascogale is one of the two extant members of the Phascogale genus; however, no immunological studies have been reported for the brushtailed phascogale (Phascogale tapoatafa), and in the current report, the term phascogale is used to specifically refer to the red-tailed phascogale. Phascogales are small, nocturnal, arboreal, and mainly insectivorous marsupials (Bradley, 1997;Stannard et al., 2010). Phascogale pouch young spend the first 44 days of life in a period of fixed lactation and are fully weaned by 110 days postpartum (Foster et al., 2006). ...
Article
Red-tailed phascogale (Phascogale calura) pouch young at birth were relatively underdeveloped in comparison to their eutherian counterparts, and the lymphoid tissues of the immune system were found to be histologically immature. The phascogale thymus rapidly developed in the first few days of pouch life, and was quickly populated with lymphocytes. By the end of pouch life, involution of the thymus was underway. The bone marrow started to develop in the early stage of pouch life, although adipocytes and megakaryocytes were not observed until slightly later. The liver was hematopoietic from birth and reached histological maturity towards the end of pouch life. The lymph nodes were difficult to detect macroscopically due to their small size, but were easily identified microscopically later in pouch life, particularly in the mesentery, and these lymph nodes exhibited germinal centres by the end of pouch life. The early spleen was predominately mesenchymal, but exhibited some erythropoiesis. Follicles with well developed germinal centres were not observed until the latest stage of pouch life. Although intraepithelial lymphocytes were detected in the intestines early in pouch life, the discrete lymphoid aggregates and Peyer's patches characteristic of the gut-associated lymphoid tissue (GALT) were not detected until later in pouch life. This is the first report of histological development in phascogale pouch young, as well as the first report of the thymus, bone marrow and lymph nodes in this dasyurid species at any age. This article is protected by copyright. All rights reserved.
... A recent study has found that mammalian semelparity is also not unique to marsupials, with a report from an eutherian species (Smith and Charnov, 2001). There have been various attempts to interpret the evolution of mammalian semelparity (Braithwaite and Lee, 1979;Diamond, 1982;Dickman, 1993;Dickman and Braithwaite, 1992;Lee and Cockburn, 1985) including an 'adaptive-stress senescence' hypothesis (Bradley, 1997) as well as sperm competition (Dickman, 1993). ...
Article
Evidence of stress responses in Australian animals is reviewed through a series of case studies involving desert frogs and lizards, small carnivorous marsupials, desert wallabies, a dwarf kangaroo species, the quokka wallaby and a small nectarivorous bird. An operational definition of stress as "the physiological resultant of demands that exceed an animal's homeostatic capacities" is used to identify instances of stress responses in the field, and to gauge their intensity. Clear evidence of stress responses is found in small dasyurid marsupial carnivores, and desert agamid lizards, both of which are semelparous. Other instances of seasonal stress responses include the Rottnest Island quokka, the barrow Island euro kangaroo and a small nectarivorous bird, the Silvereye. The review also highlights the high level of physiological adaptation of some desert wallabies, such as the Spectacled hare wallaby, which is able to maintain physiological homeostasis in the field when challenged by conditions of extreme drought. The importance of thermal and hygric refugia for the long-term survival or rock wallabies, which apparently lack any hormonal control of renal function, is also highlighted.
... However, such plasticity in teat number now seems, in part, to be attributable to previously unrecognised interspecific variation within species complexes (Dickman et al. 1998). Among Phascogalinae (Antechinus and phascogales) it generally appears that teat number is stable (not variable) within local 'populations', with the clearest examples including A. minimus (Cockburn et al. 1983), P. calura (Bradley 1997), A. flavipes leucogaster (Carati 1981; WA Museum records), Victorian P. t. tapoatafa (Soderquist 1993), andA. subtropicus, A. adustus (Van Dyck andCrowther 2000). ...
Article
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This study details morphometric variation among the marsupial brush-tailed phascogale, Phascogale tapoatafa. The validity of phascogales from south-western and south-eastern Australia being classified as the single subspecies P. t. tapoatafa was questioned because of the substantial isolation of the south-west population; the northern Australian subspecies P. t. pirata was included in the inquiry. Discriminant function analysis performed on 18 skull characteristics (n = 50 skulls) produced separation between P. t. pirata, south-western P. t. tapoatafa, and south-eastern P. t. tapoatafa. Separation was also achieved between female phascogales from Victoria and those from New South Wales and southern Queensland, but not between the males of these two populations. Univariate tests identified significant size differences between the groups. Field data gathered on wild P. t. tapoatafa illustrate large size differences between phascogales of Victoria and south-western Australia. Phascogales from south-western Australia also exhibit a polymorphism in teat number (6, 7 or 8 teats; n = 72) that is not observed in other phascogales. This isolated population may represent a distinct taxon.
... Chronic stress associated with breeding can be associated with fatal pathology (Dickman and Braithwaite, 1992;Bradley, 2003). For example, in Antechinus species and the red-tailed phascogale (Phascogale calura), the negative feedback system that regulates GC release is abolished during the breeding season, resulting in dysregulated and increased GC release and mass mortality (Bradley et al., 1980;McDonald et al., 1986;Bradley, 1997). A decrease in plasma CBG results in an increase in total free (biologically active) cortisol to levels which appear to be immunosuppressive, decreasing serum immunoglobulins (Bradley et al., 1980). ...
Article
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Many Australian marsupials are threatened species. To effectively manage in situ and ex situ populations, it is important to understand how marsupials respond to threats. Stress physiology (the study of animals’ response to challenging stimuli), a key approach in conservation physiology, can be used to characterise the physiological response of wildlife to threats. We reviewed the literature on the measurement of glucocorticoid (GC), endocrine indicators of stress, to understand the stress response to conservation relevant stressors in Australian marsupials and identified 29 studies. These studies employed a range of methods to measure GC, with faecal glucocorticoid metabolite (FGM) enzyme immunoassay (EIA) being the most common method. The main stressors considered in studies of marsupials were capture and handling. To date, the benefits of stress physiology have yet to be fully harnessed in marsupial conservation. Despite a theoretical base dating back to the 1960s, GCs have only been used to understand how 23 of the 142 extant species of Australian marsupial respond to stressors. These studies include just 7 of the 60 marsupial species of conservation concern (IUCN Near Threatened to Critically Endangered). Furthermore, the fitness consequences of stress for Australian marsupials are rarely examined. Individual and species differences in the physiological stress response also require further investigation because significant species specific variations in GC levels to stressors can shed light on why some individuals or species are more vulnerable to stress factors while others appear more resilient. This review summarises trends, knowledge gaps and future research directions for stress physiology research in Australian marsupial conservation.
... 58 The red-tailed phascogale (Phascogale calura) is a small, arboreal, 59 insectivorous/carnivorous dasyurid marsupial currently inhabiting semi-arid, and historically 60 arid, regions of Australia (Bradley et al., 2008;Stannard et al., 2010). It has a semelparous 61 reproductive strategy, with complete male die-off after a short, synchronised breeding season 62 in July (Bradley, 1997). Since European settlement, the red-tailed phascogale's range has 63 contracted from being widespread throughout Central and Southern Australia to a small 64 pocket in Western Australia's wheat belt that receives 300-600 mL annual rainfall 65 (Kitchener, 1981;Menkhorst and Knight, 2001;Bradley et al., 2008). ...
Article
The red-tailed phascogale is a small arboreal dasyurid marsupial that inhabits semi-arid to arid regions of Western Australia's wheat belt. Its body mass (34.7 g) is only ∼15% of that predicted based on its phylogenetic position among other dasyuromorphs; we interpret this as an adaptation to its scansorial and semi-arid/arid lifestyle. The standard physiology of this species at a thermoneutral ambient temperature of 30 °C conforms to that of other dasyurid marsupials; body temperature (34.7 ± 0.37 °C), basal metabolic rate (0.83 ± 0.076 mL O2 g−1 h−1), evaporative water loss (1.68 ± 0.218 mg H2O g−1 h−1) and wet thermal conductance (3.8 ± 0.26 J g−1 h−1 °C−1) all fall within the 95% predication limits for the respective allometric relationships for other dasyurid species. Thermolability confers an energy savings at low Ta and water savings at high Ta. Torpor, observed at low Ta, was found to be more beneficial for energy savings than for water economy. The red-tailed phascogale therefore has a physiology suitable for the challenges of arid environments without any obvious requirement for adaptations to its scansorial lifestyle, other than its considerably lower-than-expected body mass.
... To explain the life-history of semelparous dasyurid species in general, and of P. calura in particular, Bradley (1997) has proposed the 'adaptive stress senescence hypothesis' to explain that males become prematurely senescent as a consequence of exposure to high concentrations of free cortisol for a protracted period prior to their disappearance from the population. The critical factors that seem to predispose males to the development of pathological changes are outlined in Table 1. ...
Chapter
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This chapter covers some of the basic ecological, behavioural and physiological changes that have been reported in studies of dasyurid marsupials exhibiting the unusual post-mating male mortality (life-history Strategy 1). Rather than attempting to cover all reports, the chapter concentrates upon changes that the author considers to be most relevant in attempting to explain why post-reproductive males in the wild die, yet females survive. Evidence relating to a defect in feedback of corticosteroid hormones in discussed in relation to recent findings for eutherian stress models. The relevance of these studies for explaining the truncated lifespan of Strategy I dasyurid males is discussed and an integrated flow diagram is attempted to synthesise the physiological changes that are likely to occur in the weeks preceding the death of males. Considered together, the adaptive physiological changes that occur during the last few weeks of life of the males are remarkable in enabling them to maximise their reproductive potential prior to a rapid physiological decline that involves stress related dysfunction and pathologies involving renal, gastrointestinal (GI), neuroendocrine and central nervous systems.
... Maternal investment is high, and in the largest of these species, Phascogale tapoatafa, wild litters weigh an average 313% of maternal body weight at weaning (Soderquist 1993a). Supernumerary young are born (Woolley 1966;Cuttle 1982;Bradley 1997) and females initially attempt to raise as many young as they have teats although accidental loss, and occasionally infanticide, can reduce litter size over the course of lactation (Cockburn et al. 1983;Cockburn 1990). ...
Article
Reproduction and population demographics were examined among wild brush-tailed phascogales in southern Western Australia. Data were gathered in a single region during 1992–97 from 387 individuals, 139 of whom were monitored by radio-telemetry. In contrast to Victorian phascogales, which all have eight teats, the Western Australian population contained females with six (30%), seven (21%), and eight (49%) teats (n = 72). Teat numbers varied between mothers and daughters/sisters, which appears unprecedented among dasyurids. The data strongly suggest that females try to raise as many young as they have teats. Population changes are as described for Victorian phascogales: complete male die-off occurs in July; some females survive to breed in a second year; and there is long-distance male dispersal and high philopatry by female offspring. Births occur from July to September, somewhat later and also less synchronised than among Victoria phascogales. Late breeding by females in one year suggests that sperm storage may be extensive in this species. Strong associations between the physical condition of females and rainfall suggest that these may influence between-year variation in birth times and sex-ratio bias in litters. Similarly, poor physical condition of young during drought may have underpinned atypical dispersal behaviour in males. Decreased teat numbers and smaller litter sizes indicate that phascogales from south-western Western Australia are reproductively adapted to relatively low food availability. However, this species experiences difficulty successfully breeding and rearing young under drought conditions.
... However, both this species and its congener, the red-tailed phascogale (P. calura), were formerly distributed in far more arid areas (Baynes 1987;Bradley 1997), where rainfall is both low and unreliable. Given the seeming importance of food limitation in the jarrah forest, and its apparent relationship with drought, the occurrence of the brush-tailed phascogale in areas such as the Nullarbor Plain (Baynes 1987) presents a paradox. ...
Article
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The diet and foraging behaviour of an arboreal marsupial, the brush-tailed phascogale (Phascogale tapoatafa tapoatafa), was examined in the jarrah forest of south-western Australia. Radio-tracking was used to confirm the species’ nocturnal foraging habit and to make direct observations of foraging behaviour. Eleven stomachs, and a collection of 45 scats obtained during summer and autumn, were microscopically examined for content. The availability of major prey items (invertebrates found on or under the bark of tree trunks) was quantified. Phascogales proved to be foraging generalists, and their diet predominantly consisted of invertebrates. Some invertebrate taxa appeared to be preferred but few taxa were avoided. Active pursuit of vertebrates was negligible. However, the species appears opportunistic, and scavenging of vertebrates may contribute to the diet. Nectar was also taken, appearing to be a particularly prized but rare and patchy food source. It is suggested that the current and former distributions of this species have been constrained by both the seasonal reliability of rainfall and the diversity of food resources.
... Phascogales are Strategy 1 breeders, and are therefore monoestrus and have a highly synchronised breeding season (Lee et al. 1982). In the wild, this species exhibits complete male semelparity, whereby all males die at 11.5 months of age after mating (Bradley 1997). In captivity, males become infertile after their first breeding season but can live for 2 years (pers. ...
Article
This paper reports successful breeding by 4-year-old female red-tailed phascogales (Phascogale calura) and that they can survive until at least 5 years of age in captivity, whilst males can survive until at least 2 years of age in captivity. These findings have implications for captive breeding programs, providing evidence that older females can be successfully bred. In the longer term we hope these findings may aid conservation efforts of this endangered dasyurid.
... Obligate male die-off is considered to be a selective advantage because of enhanced survivorship of offspring. During the breeding period, endocrine changes in males enhance mating success, with the ultimate cost of hormonally accelerated aging and senescence (Bradley 1997). However, this is only advantageous where resources are limited such that there would be strong competition between adult males and subadults after weaning. ...
Article
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The post-mating mortality of males in dasyurid species is thought to be a specific life-history strategy, associated with a tightly synchronised breeding season, that may enhance survivorship of juveniles. Parantechinus apicalis has been reported to exhibit male die-off in island populations but not in mainland populations, and males originating from both island and mainland populations are known to survive post-mating in captivity. However, males in the island populations have been reported to sometimes survive to breed in a second year. This study monitored captive and island populations over a three-year period (April 1997 – May 2000) to examine the extent of male die-off. In captivity, males showed no evidence of post-mating mortality. Males on one island were also found to survive post-mating, while another island population appeared to have high mortality of males in three years, and a complete male die-off after the 1999 breeding season. We conclude that P. apicalis may warrant inclusion in a new category of life-history strategy for species exhibiting facultative male die-off.
... Red-tailed phascogales were once widespread throughout Central Australia, including Alice Springs and other areas of the Northern Territory, New South Wales, Victoria and South Australia (Smith & Medlin, 1982;Bradley, 1997). The current distribution of the red-tailed phascogale is limited to a small area in the south-western Western Australia vegetated with Eucalyptus wandoo and Casuarina huegeliana (Kitchener, 1981;Bradley et al., 2008). ...
Article
Red-tailed phascogales Phascogales calura are near-threatened (Friend, 2008) arboreal Dasyurids. A breeding programme was established at Alice Springs Desert Park in 2001 to aid species recovery. Twenty-five captive-bred phascogales were released into a suitable habitat at the park in 2006. If shown to be successful, the initial release was to be expanded with the release of further captive-bred phascogales into a suitable habitat in the nearby National Park and into South Australia. In this study, a dietary analysis was conducted to determine the preferred diet of the translocated phascogales in the park environment. Scats were collected during July–October, 2006 and January–March, 2007 from nesting sites within the park. Faecal samples were weighed, soaked in hot water and particles were separated through sieves before examination under a microscope. Scat analysis methods identified that red-tailed phascogales were primarily insectivorous with 92.6% of all scats containing arthropods. They are also opportunistic predators within the park, consuming birds (51.6%), small mammals (33.3%) and on occasion reptiles, and plant material (27.4%). Seasonal comparison of data through SIMPER analyses showed there was significant variation (P=0.009) between spring and summer, due to a large portion of birds present in the diet in spring. The red-tailed phascogale is able to exploit a number of prey types and it is therefore likely that they would survive a ‘hard’ translocation into the wild provided the site chosen has adequate food supply.
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Context Predation by feral cats continues to place substantial pressure on native Australian wildlife, contributing to significant population declines and localised extirpations of susceptible species. In Western Australia (WA), the registration of the poison bait Eradicat® provides a tool to help manage these introduced predators, but only in areas where the risk to non-target species is considered acceptable. The red-tailed phascogale (Phascogale calura), a small carnivorous marsupial now restricted to vegetation remnants in the highly fragmented agricultural zone of south-western WA (i.e. the Wheatbelt), is one species that may be vulnerable to lethal ingestion. Aim To investigate the impact of repeated Eradicat® baiting, to control feral cats, on the activity levels of the red-tailed phascogale, focusing on populations in two Wheatbelt conservation reserves. Methods We established a novel approach to monitoring red-tailed phascogales by using tree-mounted camera trap arrays in an area with feral cat management using ground-delivered Eradicat® baits, and two control zones with no feral cat management. We examined changes in activity levels (detection rate and occupancy) based on camera trap detections, before and after Eradicat® application, across two autumn and two spring baiting events. We also investigated non-target bait uptake using camera traps. Key results Although a small number of baits (7/60) was removed by red-tailed phascogales from the field of view of a camera, our results showed no overall impact of Eradicat® on their activity levels within the study area. Tree-mounted camera traps proved to be highly effective and efficient at detecting red-tailed phascogales. To maximise camera detections, the optimal time for monitoring red-tailed phascogales is during autumn, prior to male die-off. Conclusions Our results suggested that the risk posed to red-tailed phascogale populations from the repeated use of Eradicat® baits is likely to be low. Implications Integrating the application of Eradicat® to control feral cats with existing fox control in conservation reserves that support populations of red-tailed phascogales is likely to pose minimal risk to the species.
Article
Effective monitoring methods are required to evaluate the success of wildlife reintroduction programs. To improve the threat status of the Vulnerable red-tailed phascogale (Phascogale calura), the Australian Wildlife Conservancy reintroduced the species to a fenced reserve at Mt Gibson Wildlife Sanctuary. After trialling a variety of post-release monitoring methods, remote camera monitoring and arboreal trapping with an extensive period of pre-luring provided the most information with which to evaluate the success of the reintroduction. To date, reintroduced red-tailed phascogales have increased in both occupancy and population size following releases which began at Mt Gibson in 2017. Other managers of red-tailed phascogale populations may find the described methods useful, particularly in the context of multi-species reintroductions where trap saturation can reduce capture rates of smaller species, such as phascogales.
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All mammals are characterized by the ability of females to produce milk. Marsupial (metatherian) and monotreme (prototherian) young are born in a highly altricial state and rely on their mother's milk for the first part of their life. Here we review the role and importance of milk in marsupial and monotreme development. Milk is the primary source of sustenance for young marsupials and monotremes and its composition varies at different stages of development. We applied nutritional geometry techniques to a limited number of species with values available to analyze changes in macronutrient composition of milk at different stages. Macronutrient energy composition of marsupial milk varies between species and changes concentration during the course of lactation. As well as nourishment, marsupial and monotreme milk supplies growth and immune factors. Neonates are unable to mount a specific immune response shortly after birth and therefore rely on immunoglobulins, immunological cells and other immunologically important molecules transferred through milk. Milk is also essential to the development of the maternal-young bond and is achieved through feedback systems and odor preferences in eutherian mammals. However, we have much to learn about the role of milk in marsupial and monotreme mother-young bonding. Further research is warranted in gaining a better understanding of the role of milk as a source of nutrition, developmental factors and immunity, in a broader range of marsupial species, and monotremes.
Article
Stress is ubiquitous and thus, not surprisingly, many hypotheses and models have been created to better study the role stress plays in life. Stress spans fields and is found in the literature of biology, psychology, psychophysiology, sociology, economics, and medicine, just to name a few. Stress, and the hypothalamic-pituitary-adrenal/interrenal (HPA/I) axis and sympathetic nervous system (SNS), are involved in a multitude of behaviors and physiological processes, including life-history and ecological tradeoffs, developmental transitions, health, and survival. The goal of this review is to highlight and summarize the large number of available hypotheses and models, to aid in comparative and interdisciplinary thinking, and to increase reproducibility by discouraging hypothesizing after results are known (HARKing) and by encouraging a priori hypothesis testing. For this review I collected 214 published hypotheses or models dealing broadly with stress. In the main paper, I summarized and categorized 131 of those hypotheses and models which made direct connections among stress and/or HPA/I and SNS, tradeoffs, transitions, and health. Of those 131, the majority made predictions about reproduction (n = 43), the transition from health to disease (n = 38), development (n = 23), and stress coping (n = 18). Additional hypotheses were classified as stage-spanning or models (n = 37). The additional 83 hypotheses found during searches were tangentially related, or pertained to immune function or oxidative stress, these are listed separately. Many of the hypotheses share underlying rationale and suggest similar, if not identical, predictions, and are thus not mutually exclusive; some hypotheses spanned classification categories. Some of the hypotheses have been tested multiple times, whereas others have only been examined a few times. It is the hope that multi-disciplinary stress researchers will begin to harmonize their naming of hypotheses in the literature so as to build a clearer picture of how stress impacts various outcomes across fields. The paper concludes with some considerations and recommendations for robust testing of stress hypotheses.
Article
We propose a practical concept that distinguishes the particular kind of weaponry that has evolved to be used in combat between individuals of the same species and sex, which we term intrasexually selected weapons (ISWs). We present a treatise of ISWs in nature, aiming to understand their distinction and evolution from other secondary sex traits, including from ‘sexually selected weapons’, and from sexually dimorphic and monomorphic weaponry. We focus on the subset of secondary sex traits that are the result of same‐sex combat, defined here as ISWs, provide not previously reported evolutionary patterns, and offer hypotheses to answer questions such as: why have only some species evolved weapons to fight for the opposite sex or breeding resources? We examined traits that seem to have evolved as ISWs in the entire animal phylogeny, restricting the classification of ISW to traits that are only present or enlarged in adults of one of the sexes, and are used as weapons during intrasexual fights. Because of the absence of behavioural data and, in many cases, lack of sexually discriminated series from juveniles to adults, we exclude the fossil record from this review. We merge morphological, ontogenetic, and behavioural information, and for the first time thoroughly review the tree of life to identify separate evolution of ISWs. We found that ISWs are only found in bilateral animals, appearing independently in nematodes, various groups of arthropods, and vertebrates. Our review sets a reference point to explore other taxa that we identify with potential ISWs for which behavioural or morphological studies are warranted. We establish that most ISWs come in pairs, are located in or near the head, are endo‐ or exoskeletal modifications, are overdeveloped structures compared with those found in females, are modified feeding structures and/or locomotor appendages, are most common in terrestrial taxa, are frequently used to guard females, territories, or both, and are also used in signalling displays to deter rivals and/or attract females. We also found that most taxa lack ISWs, that females of only a few species possess better‐developed weapons than males, that the cases of independent evolution of ISWs are not evenly distributed across the phylogeny, and that animals possessing the most developed ISWs have non‐hunting habits (e.g. herbivores) or are faunivores that prey on very small prey relative to their body size (e.g. insectivores). Bringing together perspectives from studies on a variety of taxa, we conceptualize that there are five ways in which a sexually dimorphic trait, apart from the primary sex traits, can be fixed: sexual selection, fecundity selection, parental role division, differential niche occupation between the sexes, and interference competition. We discuss these trends and the factors involved in the evolution of intrasexually selected weaponry in nature.
Chapter
For several decades, senescence has been considered as non-existing in free-ranging mammalian populations simply because most animals were expected to die from environmentally driven causes of mortality before the age at which senescence starts. Thanks to an increasing number of long-term individually based monitoring schemes of known-age animals in the wild, evidence of senescence in most life history traits has been reported in a large number of species across all mammalian orders. From a review of these studies, we found that actuarial senescence is the rule rather than the exception in most mammalian species studied so far.We also found clear evidence for reproductive senescence, especially in long-lived primates and ungulates, in which the oldest individuals show the existence of post-reproductive life. Senescence in life history traits is thus pervasive among mammalian species, and the key topics are now to assess the causes and consequences of senescence in mammalian population dynamics and to understand variation in the magnitude and targets of senescence among and within mammalian species. Published analyses have identified the intensity of sexual selection, the environmental context and some physiological and genetic mechanisms as major structuring factors shaping mammalian senescence within and between species. Although not yet quantified in most studies, the fitness costs of senescence do not appear as negligible as generally assumed and warrant further investigation.
Article
Stress response is an evolved suite of physiological, hormonal and behavioral responses exhibited by individuals that are highly conserved across vertebrate taxa. Most of what is known about stress comes from the biomedical and neuroendocrinological research community. Although Hans Selye's original work addressed how individuals adapt to stressor, many recent studies have mainly focused on negative effects of stress on fitness of individuals and diseases related aspects of stress. However, it is very difficult to imagine that stress has evolved simply to make animals sick over millions of years. From the point of view of evolution, we summarizes the relationships between stress responses and reproductive strategies, as well as different coping styles when animals were exposed to stressors. We also analyze the adaptive roles of stress responses and the coping styles in mammals.
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Background: Dromiciops gliroides is a small nocturnal marsupial found in the temperate forests of Southern Chile and Argentina. It is the only living member of the order Microbiotheria. Here, we describe the discovery and first account of live trapping of D. gliroides in Parque Nacional Los Alerces (Los Alerces National Park) in the province of Chubut, Argentina. This account extends the distribution of this cryptic species south to Parque Nacional Los Alerces (PNLA). The study provides a description of the habitat they were captured in after a recent bamboo flowering and seeding event and subsequent rodent irruption, the first in 70 years in PNLA. Results: Four adult D. gliroides were captured during the study period, and both adult females captured had pouch young present, suggesting birth occurred in late October or early November. Habitat surveys revealed D. gliroides inhabited Nothofagus forest. A lack of fruiting plants in PNLA during the trapping period (spring) suggests their diet is likely restricted to insects at this time. No dreys were detected during habitat surveys, and hence, it is likely D. gliroides utilises tree hollows as refuges and nesting sites in PNLA. Significant threats to the population in PNLA were identified including introduced predators and human-related impacts due to farming and tourism. Conclusions: There is a breeding population of D. gliroides present in Parque Nacional Los Alerces. The newly discovered population now represents the most southern location for D. gliroides in Argentina.
Article
The common brushtail possum (Trichosurus vulpecula) is an important browsing herbivore in its native Australia and in New Zealand, where it has become a major introduced pest. Possums exhibit marking behaviour, and have specialised scent glands, indicating that they use olfactory communication for social interactions. This review summarises what is known of the scent glands of the possum and some other marsupials. Although the anatomy and histology of the glands has been well-described, the composition of their secretions is only beginning to be characterised, and very little is known about their physiological control and role in possum biology.
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Habitat constrains and shapes successful ecological and physiological strategies and thus provides the context for the evolution of life-history traits. The stress axis plays a vital role in the endocrine system and is a critical component adapting mammals to particular habitat pressures. It is subject to both individual activational and organizational plasticity as well as to evolutionary modification. To illustrate, I examine the suite of traits of the stress axis associated with breeding frequency in male mammals, which varies in a continuum from semelparity to iteroparity. During the breeding season, males in species at the semelparous end of the continuum exhibit high concentrations of free corticosteroids, low concentrations of glucocorticoid-binding protein, a failure of the negative feedback system, a gonadal axis that is not inhibited by high corticosteroid concentrations, and immunosuppression. Iteroparous species exhibit the opposite traits. The evolutionary constraints selecting for the former may partially be related to phylogeny (in marsupials) as well as to an interaction of the restrictions imposed by the environment on female reproduction, the mating system, the high costs of reproduction, and the low adult survival during the nonbreeding season.
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The red-tailed phascogale (phascogale calura) is an endangered dasyurid from southwestern Western Australia that has been bred in captivity since 2001. It is an annual breeder that has a restricted breeding period, and males only participate in a single breeding season. We examined the reproductive biology of female red-tailed phascogales, assessing methods for detection of estrus, variation in the timing of breeding in captivity across facilities and years, and reproductive success. Body mass and pouch changes were useful indicators of estrus, whereas assays for fecal estradiol and progesterone did not allow for accurate prediction of ovulation. Females mated with multiple males and matings occured over a period of at least 5 days, with females storing sperm in the lumen and crypts of the oviduct. Births tended to occur in July at Alice Spring Desert Park, with births at Adelaide Zoo occurring from early June to late August. The predictable births at Alice Sprngs are similar to those observed with Antechinus, but with flexibility remaining in the reproductive strategy of the species as observed at Adelaide. Of the 146 breeding females at Alice Springs, 127 females produced 846 pouch young, of which 68% were weaned. A female bias was observed in weaned young. Information gained from this study was been incorporated into the captive-breeding program for this species.
Article
Adaptive adjustments in offspring sex ratios in mammals have long been reported, but the conditions and mechanisms that prompt shifts in the proportion of sons and daughters born are still unclear. Empirical evidence indicates that offspring sex in mammals can be related to a diversity of environmental and maternal traits. However, the underlying assumptions regarding offspring and maternal fitness are rarely tested. Physiological mechanisms of maternal selection of offspring sex may occur at many stages during the prolonged maternal investment stage, and a pluralistic approach to studying mechanisms might prove fruitful. This review highlights the apparent frequency, in marsupial mammals, of sex ratio bias, which has largely been recorded as conforming to one of a few hypotheses. Marsupials are ideally suited to experiments involving cross‐fostering of offspring, which can allow rigorous tests of the fitness consequences of rearing one sex vs. the other. The reproductive biology of marsupials lends the group to detailed studies of the timing and physiological correlates of offspring sex biases. Many components of metatherian biology may prove advantageous in experimental studies of sex allocation in mammals, and together may provide a prosperous avenue for examining adaptive and mechanistic hypotheses in mammalian sex allocation.
Article
The life histories of carnivorous marsupials, or dasyurids, make them useful subjects for studying maternal investment, such as sex ratio and lactational investment. One group of annual breeding dasyurids are male semelparous, strongly sexually dimorphic, produce large litters that weigh two to three times the weight of the mother at weaning and show biases in siring success and sex ratio. Red-tailed phascogales Phascogale calura belong to this group and in captivity they have shown biases in siring success with body weight. The growth rates of young of this species were investigated to determine whether sex-biased maternal investment occurs. No relationship was evident between maternal weight and the sex ratio of young, indicating no sex-ratio adjustment with maternal condition. In contrast, a positive relationship was evident between maternal weight and the weight of offspring at weaning, with weaning weight being correlated with weight at maturity. Dimorphism in weight emerged during suckling, with an average dimorphic ratio of 1.5 achieved by maturity. In contrast, dimorphism in skeletal measures did not emerge until after weaning, with an average dimorphic ratio of 1.14 achieved by maturity. The sex differences in growth during suckling provide support for a male bias in maternal investment.
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Blood samples were taken from a wild population of red-tailed phascogale Phascogale calura at intervals up until the annual post-mating disappearance of males. While sexual dimorphisms in haematological and blood chemical values were not found, there were detected some age-related changes. Reductions in haematocrit and haemoglobin concentration between mid- and late-July were detected both in females and males but contrary to the finding in another small dasyurid sharing this unusual life history pattern, these decreases in the males could not be described as anaemias. The changes in erythrocyte parameters in the blood of females at about this time conform to the pattern of a macrocytic anaemia which may be nutritionally based. A marked lymphocytopenia and neutrophilia observed at the end of July in males, but not in females, is consistent with other evidence of the development of a stress response.
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Phascogale tapoatafa, an arboreal carnivorous marsupial, is the largest mammal in which an obligate yearly die-off of all males occurs. The species is one of the most widespread of Australian marsupials, being found in tropical, subtropical and temperate forests and woodlands of Australia. Its breeding season varies little throughout this range, with most births occurring in July. In three Victorian populations, 2-year-old females typically gave birth earlier than first-year females, births were spread on average over 15 days, and, in some years, occurred two weeks earlier than average. Modal litter size equalled the number of teats (8), but litters of 1-6 young comprised 29% of the sample (n = 45), and litter size averaged 6.6 young. The sex ratio of litters produced by second-year females was significantly male-biased (0.62); that of first-year females was 0.48. When juveniles first released the teats (c. 48 days of age), they weighed about 4 g. Weight gain by captive juveniles was more rapid than that of wild conspecifics prior to weaning, but skeletal growth rate and morphological development were similar. Total lactational investment by P. tapoatafa is much greater than expected for a dasyurid of its size (wild litters at weaning average 313% of maternal weight; captive litters average 370%). The high mortality of wild adult females during lactation may reflect this energetic drain.
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Reproduction in male Antechinus minimus maritimus was investigated in the field and laboratory by morphological, histological and endocrinological techniques. All males died in late July or early August immediately after mating. Testicular weight was maximal in May and then declined abruptly in June. Spermatogenesis lasted from February to May. The germinal epithelia of some tubules at the time of testicular regression consisted of only Sertoli cells, while in others some spermatogonia were also present. Prostate and Cowper's glands were maximally enlarged in June and July, which coincided with the maximal concentration (5 ng ml-¹) of androgens in the blood. During the rest of the year concentrhtions were less than l ng ml-¹. It is concluded that reproduction in male A. m. maritimus is essentially the same as in other Antechinus which exhibit male 'die-off'. The low concentrations of plasma androgens during spermatogenesis in Antechinus indicate that if these steroids are important for spermatogenesis, only relatively small amounts are required.
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A trapping study of Antechinus stuartii was conducted in subtropical rain forest in 1971-72. Juveniles were communal during the period of abundant food and became solitary in autumn when food diminished. Dyad testing in a field observation cage permitted analysis of social dominance in males. Dominant males had individual ranges in habitats where resources permitted rapid growth throughout winter, whereas subordinate males, in poorer habitat, grew slowly. As winter mortality was low, the advantage of this superior food resource base may lie during the mating season, the more energetic dominant males being able to mate with more females. The probability of contribution to the gene pool by subordinate males appears low. Selection for high male reproductive effort is intensified by the brief annual mating season in this monoestrous species. The life history of this species appears to be geared to predictable seasonal food resources, but it may not be optimal throughout the present range, and the species appears to be evolutionarily trapped.
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Seasonal changes in some basic bioenergetic functions were investigated in the marsupial mouse A. flavipes by comparing normal males with females and castrated males. The activity and body weight of intact males increased to a peak in late June, at the same time metabolic rate increased. After the period of maximum testis development from late June to the end of July the activity of males declined, as did body weight and scrota1 width. The pelage of intact males also deteriorated, while the female and castrated males remained sleek and maintained weight. The metabolic rate of intact males also declined after the breeding season, whereas that of the castrated males remained constant. Despite a decline in body weight, intact males showed an increase in energy consumption in July which remained high in August and September; faecal energy loss was lower in September than July. Energy consumption in castrated males did not increase until September, faecal energy loss did not change during the year. The differences observed among intact males, castrated males and females suggests that the male sex hormone system influences the metabolic and hormonal changes associated with male mortality.
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Hydroxyproline concentration, as a measure of collagen, was determined in the skin of freshly captured male A. stuartii. The mean concentration increased between 30 and 38 weeks of age, decreased between 38 and 41 weeks, and increased again between 46 and 49 weeks. These changes do not support the hypothesis that males age rapidly before their mortality at approximately 51 weeks old. Peak concentration of skin hydroxyproline coincided with periods when the plasma corticosteroid concentrations were increased in males in the natural population. Exogenous cortisol increased the concentration of skin hydroxyproline in laboratory-held males. Therefore, the increase in hydroxyproline concentration in field males appears to result from high titres of plasma corticosteroids.
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Quantitative data are presented on population size and structure, mortality, breeding, growth, movements, and activity during a 3-yr live-trapping study. The population reached a peak each autumn and declined to low numbers each spring. A few females survived to breed a second time but males suffered 100% mortality in each breeding season. Death after mating was not inevitable under laboratory conditions. Mating occurred only in the last 2 weeks of September each year in the field. Pregnancy lasted about 1 month, and lactation about 3 months. Juveniles attained sexual maturity at 11 months of age. Though A, stuavtii is usually nocturnal-crepuscular, some diurnal activity occurred; and extensive arboreal activity was recorded. Male home ranges were larger than those of females, and expanded farther during the breeding season. Mortality had a greater influence on population size than reproduction. Late sexual maturity and stereotyped reproductive pattern seem to preclude cyclical changes in population density.
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In a capture-mark-release program on Antechinus bilarni at Little Nourlangie Rock, N.T., from February 1977 to June 1979, 34,800 trap nights were set, for a total catch of 174 males and 162 females. Breeding is strictly seasonal, with mating around late June. Pouch young are carried in August and September. Lactation continues until December, when free-living young are first trapped. Males show a seasonal increase in testes size, with a decrease after mating. There is no die-off of males; both males and females may survive for a second breeding season. Males undergo a second cycle of increase in testes size, and histological sampling revealed spermatogenesis during their second breeding season. Individual males and females were trapped for up to 24 and 25 months respectively; KTBA estimates are similar for both sexes. Both sexes continue to increase in body weight throughout life. although males lose weight substantially after each breeding season. Sex ratios dropped during October of each year because the activity and trappability of males dropped. Males were recaptured with the onset of the wet season. The preferred habitat was scree slope, at an altitude of around 40-55 m. Some seasonal shifts in habitat were probably related to food availability.
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The difficulty of observing the behaviour of cryptic, nocturnal carnivorous marsupials (Dasyuridae) in the wild has created a reliance on laboratory studies for the analysis of social interactions. Behavioural data on wild Phascogale tapoatafa suggest that previous interpretations may be biased by laboratory confinement. The play of juvenile P. tapoatafa entailed brief, non-contact chases, which apparently provide social practice prior to the solitary, post-dispersal life of adults. Interactions between wild adults very rarely included physical contact. Most encounters (63%) comprised chases, of which only female-female interactions commonly displaced the chased animal more than 3 m. Wild females readily deterred males from approaching closely by vocal threatening, even during the peak of the breeding season, so that forced copulation (as reported in captive dasyurids) was unlikely. Scent-presentation experiments suggested that sternal marking by males was intersexual communication, and may serve, along with intersexual chases, to familiarise females with future mates.
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A population of the fawn antechinus, Antechinus bellus, was monitored in tropical open-forest of the Northern Territory between June 1980 and January 1983. Sixty males and 66 females were captured and marked over 9525 trap-nights. The species exhibits the typical Antechinus life-history strategy, characterized by a highly synchronized mating period after which all males die. This field evidence supports earlier speculation based on laboratory studies and limited museum collections. Mating occurs over 2 weeks in late August and parturitions about a month later. Young remain attached to the nipples for 4-5 weeks and are suckled in the nest until weaned in early January. Reproduction patterns, population dynamics and changes in relative abundance resemble those in A. stuartii from south-eastern Australia. The life-history strategy of A. bellus contrasts with that of the regionally sympatric Parantechinus bilarni, in which fecundity is lower and males may survive to breed a second time. The strategy exemplified by A. bellus does not seem optimal for the wet-dry tropics, given the erratic nature of rainfall in the early wet season, which may influence the relative abundance of the insect food resource available for lactating females and newly weaned juveniles. However the existence of patches of structurally diverse open-forest may moderate environmental fluctuations and enhance resource availability, and thus be of critical importance for the survival of local populations.
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The cause of population cycles in microtines (voles and lemmings) remains an enigma. I propose a new solution to this problem based on a crucial feature of microtine biology, shifts in age structure, that has been ignored until now. Empirical evidence indicates that age structure must shift markedly towards older animals during declines because of three characteristics of the previous peak year: a shortened breeding season, total replacement of the breeding population from peak to decline and density-dependent social inhibition of maturation of young. Declines become inevitable as populations composed of older animals survive and reproduce poorly because of the effects of senescence, possibly interacting with the experiences of peak density and I present both theoretical and empirical evidence for this hypothesis. Although a variety of physiological systems deteriorate with aging, I focus on a crucial one — the inability of older animals to effectively maintain homeostasis in the face of environmental challenges because of a progressive deterioration in the endocrine feedback mechanisms involved in the hippocampal—hypothalamic—pituitary—adrenal axis. Microtine populations will not exhibit cycles where age structure shifts are prevented owing to extrinsic factors such as intense predation. Six testable predictions are made that can falsify this hypothesis.
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Female brown marsupial mice were mated and changes in the number and distribution of spermatozoa were assessed in several regions of the reproductive tract at 1, 2, 3, 7, 10, 14 and 18 days after mating. Approximately 40 x 10(3) spermatozoa/side were present in the female reproductive tract between Days 1 and 7 after a single mating. This had decreased (to approximately 9 x 10(3) spermatozoa/side) by Days 10 and 14 after mating; by Day 18 no spermatozoa were recovered. The maximum number of spermatozoa recorded in a female tract was approximately 72 x 10(3) spermatozoa/side (Day 5 female, death in laboratory) and the minimum recorded was approximately 2 x 10(3) spermatozoa/side on Day 2 after mating. Between Days 1 and 7 after mating most spermatozoa were located in the uterus and lower isthmus (isthmus 1) and spermatozoa were rarely found in the lateral vaginae. By 24 h after mating most spermatozoa (approximately 60%) were found in isthmus 1, but approximately 35% were still present in the uterus. Histological observations of the lower isthmus at this time showed that large numbers of spermatozoa were present in both the lumen of the duct and the sperm storage crypts which are located in this region. By Day 7 after mating approximately 91% of all spermatozoa in the female tract were in isthmus 1, most of these being confined to the sperm storage crypts. On Days 10 and 14 after mating almost all spermatozoa in the tract were in the crypt regions of isthmus 1 and on Day 18 degenerating spermatozoa were observed. No special orientation or association of spermatozoa in relation to crypt cells was observed. These results show that, although the number of spermatozoa inseminated is low by mammalian standards sperm transport in this species is extremely efficient and a large proportion of spermatozoa reaches the isthmus before ovulation (approximately 1 in 1 to 1 in 7). Several observations may explain the remarkable success of these low numbers of spermatozoa, including specializations of the reproductive tract which may have a directing effect on sperm movement and the special relationship which exists between spermatozoa and the oviducal environment which results in viable sperm storage. Recent observations suggest that an unusual sinusoidal mode of progressive motility observed in this species, may also influence the success of the low numbers of ejaculated spermatozoa.
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Glucocorticoids (GCs) can damage neurons of the hippocampus, the principal target tissue in the brain for the hormone. Hippocampal neuron loss during aging in the rat is accelerated by prolonged GC exposure and decelerated by adrenalectomy. GCs appear to damage these neurons indirectly by inducing a state of vulnerability and thus impairing their capacity to survive a variety of metabolic challenges. As such, high physiological concentrations of the steroid increase hippocampal damage induced by an antimetabolite toxin, an excitotoxin, or hypoxia-ischemia. Conversely, adrenalectomy attenuates the damage caused by these insults. This study suggests that GCs endanger hippocampal neurons by impairing their energy metabolism. Neurons are extremely vulnerable to such disruption, all the insults potentiated by GCs either impair energy production or pathologically increase energy consumption, and GCs inhibit glucose utilization in the hippocampus. Administration of different brain fuels--glucose, mannose, fructose, or the ketone beta-hydroxybutyrate--reduced hippocampal damage induced by coadministration of GCs and either of 2 different neurotoxins (kainic acid and 3-acetylpyridine). This appeared to be due to a reduction in the damaging synergy between GCs and the toxin; as evidence, a dose of mannose that attenuated damage induced by kainic acid plus GCs failed to reduce damage induced by the same dose of kainic acid alone. Glucose (whose utilization is noncompetitively inhibited by GCs) and fructose (which does not readily penetrate the blood-brain barrier) were less effective at reducing damage than the other 2 fuels.
Book
The ecological literature on marsupials is dominated by descriptive natural history, and there has hitherto been little attempt at either synthesis or evolutionary interpretation. This book attempts to provide such a synthesis, by drawing on both the descriptive data base and predictions from the burgeoning literature on behavioural and evolutionary ecology. It documents the excellent potential the study of marsupials provides for resolution of theoretical questions of general importance in biology. It does this in three ways. First, by describing the impressive diversity of marsupial life history strategies and trophic roles. Second, by careful comparison with the eutherians, the scope of the marsupial radiation is used to analyse the role of developmental constraints and adaptive radiation in determining the diversification of higher taxa. Lastly, it is suggested that the accessibility of marsupial young during their obligatory pouch life facilitates measurement, manipulation and assessment of kinship not possible in other mammalian groups. Further special topics include marsupial/plant mutualism, marsupial competition and the empirical uses of mammals with simple life histories.
Article
This outline of statistics as an aid in decision making will introduce a reader with limited mathematical background to the most important modern statistical methods. This is a revised and enlarged version, with major extensions and additions, of my "Angewandte Statistik" (5th ed.), which has proved useful for research workers and for consulting statisticians. Applied statistics is at the same time a collection of applicable statistical methods and the application of these methods to measured and/or counted observations. Abstract mathematical concepts and derivations are avoided. Special emphasis is placed on the basic principles of statistical formulation, and on the explanation of the conditions under which a certain formula or a certain test is valid. Preference is given to consideration of the analysis of small sized samples and of distribution-free methods. As a text and reference this book is written for non-mathematicians, in particular for technicians, engineers, executives, students, physicians as well as researchers in other disciplines. It gives any mathematician interested in the practical uses of statistics a general account of the subject. Practical application is the main theme; thus an essential part of the book consists in the 440 fully worked-out numerical examples, some of which are very simple; the 57 exercises with solutions; a number of different compu­ tational aids; and an extensive bibliography and a very detailed index. In particular, a collection of 232 mathematical and mathematical-statistical tables serves to enable and to simplify the computations.
Book
1 The olfactory system of vertebrates.- 1.1 Anatomy.- 1.2 Odorant characteristics.- 1.3 Function of the external nares and related structures.- 1.4 Evolutionary trends.- 1.5 Summary.- 2 Sources and chemistry of vertebrate scent.- 2.1 The sites of odour production.- 2.2 Chemical composition of odorants.- 2.3 Threshold levels of perception.- 3 Detection of food.- 3.1 Responses of young to food odours.- 3.2 The detection of plant food by odorous cues.- 3.3 The detection of animal food by odorous cues.- 3.4 Scavengers.- 3.5 Quasi-parasites.- 3.6 Summary.- 4 Reproductive processes.- 4.1 Sex attraction and recognition the advertisement of sexual status.- 4.2 Detection and induction of oestrus, ovulation and lordosis.- 4.3 Courtship, mating and related behaviours.- 4.4 Pregnancy.- 4.5 Parental behaviour imprinting.- 4.6 Growth physical and psychosexual development.- 4.7 Summary and conclusions.- 5 Odour discrimination and species isolation.- 5.1 Individual odour.- 5.2 Family, population and racial odours.- 5.3 Species odours and sexual isolation.- 5.4 Summary and conclusions.- 6 Dispersion and social integration.- 6.1 Intraspecific aggression.- 6.2 The social hierarchy.- 6.3 Territoriality.- 6.4 Correlation between aggression-motivated behaviour and scent deposition.- 6.5 Summary and conclusions.- 7 Alarm and defence.- 7.1 Detection of the predator.- 7.2 Transmission of alarm or warning signals.- 7.3 Active defence.- 7.4 Protection from intraspecific attack.- 7.5 Summary.- 8 Olfactory navigation and orientation.- 8.1 Olfactory navigation.- 8.2 Homing orientation.- 8.3 Summary.- 9 Applications of researches into olfactory biology.- 9.1 Pest repellents and attractants.- 9.2 Animal husbandry.- 9.3 Miscellaneous applications.- References.- Taxonomie index.
Article
Reproduction and development were studied during six annual breeding seasons in 80 female Antechinus stuartii in laboratory colonies and in 34 females which were pregnant when trapped. Oestrus, ovulation and births were each highly synchronized within any one population from a specific locality in Victoria. Before ovulation, epithelial cells were present in the urine of the females for a mean of 20.0 clays ± 4.0 (S.D.) (N=72). Matings occurred in this period. In the colonies of animals from Kinglake, the first females came into oestrus over a 4-clay period in mid-July of 1976, 1982 and 1983. In laboratory colonies, ovulations in each year occurred over a 9 to 22-day period in the first half of August for Kinglake and Cement Creek and at later dates in August and September for animals from higher altitudes. In these colonies, half the animals or more ovulated within one week. Births were also synchronized. A similar pattern was found for field animals. Synchronization of breeding and the rate of development in A. stuartii were related to events in the life history.
Article
Litter size in the dasyurid marsupial genus Antechinus is highly correlated with nipple number, which shows macrogeographic variation between populations of the 3 species with extensive ranges in eastern Australia. Males die after their first attempt at reproduction, and females produce 1-2 litters in their lifetime. Nipple number is highest at high elevations in SE Australia, and lowest at low latitudes and on the exposed capes and promontories in SE Australia. The relationship between litter size and adult survival is equivocal, and predation pressure is unlikely to vary consistently across gradients of litter size. There appears to be a relationship between seasonality and litter size. Antechinus may produce broods which correspond to the number of young they can nourish. -from Authors
Article
Postmating death of all males is reported for the first time in field populations of two species of dasyurid marsupials, Parantechinus apicalis and Dasyurus hallucatus. These results differ from field and laboratory studies on other populations of these species, and suggest that life history variation within and between species and genera of dasyurids is more pronounced than has been suspected.
Article
Antechinus sp. have a short, highly synchronous, annual winter breeding season. Females are sexually receptive for approximately three weeks but ovulations of most females of a population occur within three or four days. In order to investigate the cues used for the timing and synchronization of this seasonal breeding, male and female A. stuartii were kept under two artificial photoperiod conditions and under four social conditions. An artificial long-day photoperiod inhibited reproduction for both males and females but short days did not facilitate breeding for either. Short-day photoperiod reduced and slightly delayed the normal seasonal rise in androgen concentrations of the males. Isolated females in natural photoperiod ovulated asynchronously, whereas isolated females which received pheromonal cues from urine and feces from females housed with other females ovulated in synchrony with them. These social cues mediating the synchrony of ovulation could not control the timing of seasonal breeding in the absence of the proper endogenous and environmental cues. The latter cues, however, did not allow for very precise timing.
Article
Firstly describes the diversity of marsupial life history strategies and trophic roles. Secondly, by comparison with the eutherians, the scope of marsupial radiation is used to analyse the role of developmental constraints and adaptive radiation in determining the diversification of higher taxa. Finally, argues that the accessibility of marsupial young during their obligatory pouch life facilitates measurement, manipulation and assessment of kinship not possible in other mammalian groups. Other topics include feeding strategies, marsupial-plant mutualism, competition, island biogeography and conservation. Antechinus is used as a paradigm (sic) in evolutionary ecology. -P.J.Jarvis after Publishers
Article
Phascogale calura, once widely distributed in Australia, is now confined to the southern Wheat Belt where it is considered an endangered species. Infor-mation, based on trapping surveys and Museum records, is presented on its breeding, diet and relative abundance in different habitats. Phascogale calura is an opportunistic feeder taking a wide range of insects with a preference for those < 10 mm in length, small birds and small mammals, particularly Mus musculus. It appears to feed extensively on the ground. Females usually give birth to eight young between mid-June and mid-August. Young are weaned before the end of October. There appears to be a post-mating mortality in males. They were most abundant in denser and taller climax vegetation communities within the frequently adjacent Eucalyptus wandoo and Casuarina huegeliana alliances. The former alliance has abundant Gastrolobium and Oxylobium species of poison plants. Phascogale calura probably survives in nature reserves in the Western Aus-tralian Wheat Belt and in Dryandra State Forest because poison plants in these reserves buffer vegetation from effects of domestic stock and feral animals. These reserves, being nature sanctuaries, are also protected to some extent from frequent burning.
Article
For the Australian wild rabbit, Oryctolagus cuniculus (L.), in experimental enclosures, the weights of submandibular, anal, inguinal, Harder's, lachrymal, and thyroid glands were analysed statistically in relation to density of population, sex, sexual activity, social status, and weight of the rabbits. A statistically significant correlation between the sexual activity of males and the weight of their anal, iguinal, and submandibular glands was demonstrated. The same correlation could not be demonstrated for Harder's and thyroid glands. There were no differences in gland weights in females between populations of different densities, but in males the inguinal and submandibular glands were significantly heavier in low-density populations. A highly significant linear relationship between social status of male rabbits and the weight of their anal and inguinal glands was found. There was a less significant relationship in the case of Harder's and thyroid glands and none in the lachrymal. A linear relationship was not demonstrated for the submandibular gland but there was a difference between the dominant males and the rest. In females the weights of anal and inguinal glands were very significantly correlated with the social status of individuals. In the case of all other glands there was no correlation with social status. Social status was significantly correlated with body weight in males but not in females. There were statistically significant differences in the weights of the inguinal, thyroid, and lachrymal glands of males from enclosures with different densities of populations. The results suggest the importance of odoriferous glands in the social and territorial activities of the wild rabbit.
Article
The olfactory exploratory and scent-marking behavior of domestic rabbits were observed in an artificial laboratory enclosure. The rabbits tended to mark certain objects more frequently than others with their chin gland secretion (chinning), apparently guided by visual characteristics; however, they preferred to sniff and chin objects which had been chinned previously over those that had never been chinned. They chinned more frequently when faecal pellets were present. Dominant male rabbits chinned objects more frequently, and subordinate male rabbits less frequently, in a freshly marked environment than in a clean one; similarly dominant males chinned more frequently and subordinates less frequently when urine from another rabbit was present. Rabbits preferentially chinned urine and faecal pellets from other rabbits over their own. The dominance relations of the rabbits were determined by analyzing the behavior patterns correlated with chasing and fleeing. One of the most characteristic features of encounters between two rabbits was a complete sexual display. Long periods of sniffing of certain substances, usually urine, by the rabbits were analyzed and found to be basically similar to sniffing and flehmen patterns shown by cats. The data support the hypothesis that the whole flehmen pattern including licking and headshaking is involved with transporting substances in solution to the vomeronasal organ.
Article
A study spanning two breeding seasons was carried out to examine the role of androgens in the control of the frontal and gular scent glands of the marsupial sugar glider Petaurus breviceps Waterhouse in a wild population. Animals were captured at monthly intervals and from these blood samples were taken and tissue biopsy samples were collected from the scent glands. Several histological parameters underwent seasonal changes which were related to changes in the plasma concentration of free plus albumin bound (‘biologically active’) testosterone. The parameters which showed significant change did so during the July-September breeding season coinciding with the peak in biologically active testosterone concentration. Castration caused a significant decrease in the nuclear diameters of gular and frontal apocrine and sebaceous gland cells, and a decrease in gular apocrine cell height. These decreases were reversed with androgen replacement therapy. The nuclear diameters of apocrine tissue cells in both scent organs are positively correlated with the plasma level of biologically active testosterone. In the gular organ, but not in the frontal organ, the depth of apocrine tissue was significantly correlated with nuclear diameter. In castration and androgen replacement studies gular apocrine tissue responded more dramatically than did frontal apocrine tissue. This suggests that the gular organ is more sensitive to testosterone than is the frontal.
Article
A study spanning two breeding seasons was carried out to examine changes in the size of the dorsal paracloacal glands and testes in the marsupial sugar glider Petaurus breviceps Waterhouse 1839. These changes were related to seasonal increases in the plasma testosterone concentration and to morphological changes in the frontal and gular cutaneous scent glands of males. Both dorsal paracloacal glands and testes underwent a seasonal cycle of development which reached its maximum during the June-September breeding season. These changes coincided with an increase in the plasma testosterone concentration and with the increase in activity of certain cell types within the frontal and gular glands. Castration caused a significant decrease in the size of the dorsal paracloacal glands, while androgen replacement was effective in restoring the glands to their pre-castration size thus demonstrating the influence of androgens upon the activity of these glands. The synchronization which exists between plasma testosterone concentration, cutaneous scent gland morphology and the size of the dorsal paracloacal glands of males, suggests that the dorsal paracloacal glands, or more likely their secretions, are important in social organization in this species.
Article
In many species of carnivorous marsupials (Dasyuridae), adult males are far heavier than females (less than or equal to 100%). The theory of maternal investment predicts that juvenile males should receive greater lactational investment than female littermates, especially if maternal condition is good, because rapid growth disproportionately benefits reproductive fitness of males. I examine the development of size dimorphism between male and female siblings of Phascogale tapoatafa and Dasyurus geoffroii and compare litters of captive mothers with food given ad lib. to litters in the wild. In captivity, sons are significantly heavier and larger than daughters prior to weaning. Wild juveniles are not sexually dimorphic in size until after they begin to forage for themselves. The ontogeny of sexual dimorphism in size among wild P. tapoatafa and D. geoffroii occurs gradually after weaning and is primarily a somatic as opposed to skeletal divergence in size. The somatic energy stores of males are catabolized during the short breeding season and allow a reduction in foraging effort during this critical period of high activity.
Article
1. An dem dunkelaktiven, baumbewohnenden Kleinbeutler Petaurus mit sozialer und territorialer Lebensweise wird die innerartliche Verstndigung durch Dfte untersucht. 2. Die Begriffe Individual-, Sippen- und Artduft werden funktionell definiert; es wird eine Aufstellung der Funktionsbereiche von Sugerdften gegeben. 3. Eine Frontal- und Sternaldrse, Drsen der Analregion und des Beutelinneren werden beschrieben. Auf eine Reihe unsicherer Duftdrsen wird kurz eingegangen. 4. Neben einer Territorialmarkierung existiert eine Eigen- und eine Partnermarkierung; die Markierung kann sowohl passiv als auch aktiv erfolgen. Sechs aktive Territorialmarkierweisen werden beschrieben. Der aktiven Duftbertragung auf Artgenossen dient ein spezifisches Verhalten. 5. Die Duftstoffe der Frontal- und Sternaldrse sowie der Analregion eines sind in ihrer Duftqualitt verschieden. 6. Erwachsene erzeugen in den genannten Regionen individuell differenzierte Dfte, die — relativ pro Sippe betrachtet — unabhngig von den Gerchen der Umgebung und der aufgenommenen Nahrung sind. Erwachsene besitzen in ihrem Beutel individuell differenzierte Duftstoffe. 7. Die Adaptation an sippeneigene und sippenfremde Dfte wird behandelt. Der Grad der Adaptation von ist spezifisch fr sippenfremde und sippeneigene Frontaldrsendfte. 8. Im Speichel von wurden Duftstoffe nachgewiesen; sie sind zumindest nach Sippen in ihrer Duftqualitt differenziert. 9. Die bei Beobachtung des Markierverhaltens festgestellte Duftbertragung zwischen Tieren, die ein gemeinsames Nest bewohnen, wurde auch experimentell festgestellt. 10. Sippenfremde Duftstoffe allein lsen nur in Ausnahmefllen Aggression aus. Zustzliche Signale sind notwendig fr eine Kampfreaktion. Bei Ausschaltung chemischer Kommunikation wird weder durch optische noch durch akustische Signale Aggression ausgelst. 11. Fr eine experimentelle Vereinigung zweier Sippen ist das Benutzen eines gemeinsamen Nestes zur selben Zeit ber mehrere Tage hin erforderlich. 12. Individuell differenzierte Dfte fungieren als Individualdfte, wenn sie persnliches Erkennen auslsen. Erwachsene und einer Sippe kennen sich persnlich. Zwischen Muttertieren und ihren Jungen bestehen ab einem gewissen Alter gegenseitige, persnliche Bindungen. Jedes zieht normalerweise nur seine Jungen auf. 13. Individuell differenzierte Dfte fungieren als Sippendfte, wenn sie ein anonymes Erkennen der Sippenzugehrigkeit bewirken. Sie sind ber die Sippenmitglieder und im Territorium verbreitet und stammen vor allem von den strksten . Nestjunge lernen ihre Sippenmitglieder zunchst anonym an Sippendften kennen (auer der eigenen Mutter). 14. Trotz der sekundren Mischung der Dfte an den Tieren werden verschiedene Einzeldfte unterschieden. 15. Zwischen dem Aufbau und dem Einhalten einer Rangordnung und Dften wurden mehrere Beziehungen festgestellt. Der Aufbau einer Rangordnung kann anonym erfolgen. 16. Artdfte bewirken das Erkennen der Artzugehrigkeit eines Tieres und geben verschiedene physiologische Zustnde an. Sie fungieren als Sexualdfte (Unterscheiden des Geschlechtes, Stimulation), bei der Unterscheidung der Altersstufen und der Brutpflege. 17. und reagieren in verschiedenen Entwicklungsstadien unterschiedlich auf bestimmte Dfte ihrer eigenen und fremder Sippen. 1. A laboratory study was made on the intraspecific communication by means of odours in the night-active, arboreal gliding phalanger Petaurus from New Guinea which has social habits. The chemical composition of the smell substances was not considered. 2. The terms Individualduft, Gruppenduft, and Artduft (individual, group, and species odour) are defined functionally. A list of functional areas of mammal odours is given. 3. A frontal and a sternal gland, glands of the anal region, and of the interior of the pouch are described. A number of glands which may produce odours is mentioned. 4. Besides a chemical marking of the territory (Territorialmarkierung) there exists a chemical marking of the individual itself and of its partner's body surface (Eigen-, respective Partnermarkierung). Marking may be active or passive. Six types of active marking of territory are described. Active transfer of smell substances to the body surface of members of the same species is accomplished through specialised behaviour. 5. The chemical substances produced by the frontal and sternal gland and the anal region of a single male differ in their smell quality. 6. Adult males produce individually different odours in the three body regions mentioned. Their differentiation within the group as a whole is independent of odours of the environs and of consumed food. Adult females produce individually different chemical substances in their pouches. 7. Adaptation to the individual's own and to other groups' odours is treated. The degree of adaptation of males to frontal gland odours of their own and of foreign groups differs considerably. 8. In the saliva of males smell substances were found. Their origin is discussed. These odours are at least differenciated among groups. 9. The transfer of smell substances between individuals observed while studying the marking behaviour was also demonstrated by experiment. 10. Odours of foreign groups release aggressive behaviour per se only by way of exception; additional signals are essential. On the other hand, if chemical communication is made impossible in experiments, aggressive behaviour can be released neither by optical nor by acoustic signals. 11. To fully integrate experimentally two groups, the use of a common nest at the same time over a period of several days is essential. Action within a common territory (outside the nest only), common group odour, or knowledge of the other group's odours does not stop aggressive behaviour between individuals if the two groups are united. 12. Individually different odours serve to distinguish both individuals (Individualdfte) and anonymous groups (Sippendfte). Adult males and females within a group recognize each other individually. Between mother and offspring there are unique mutual connections. Females usually bring up only their own young. On the other hand odours are distributed over the body surface of all the individuals of one group. They are produced mainly by the strongest males. Young animals learn first to recognize others (with the exception of the mother) as members of the group rather than as individuals. 13. Despite of the secondary mixing of smell substances on the body surface different odours remain distinguishable to the animals. 14. Several close connections were found between odours and the establishment and maintenance of a rank order. The establishment of a rank order may be by anonymous communication. 15. Artdfte (species odours) cause the identification of the species of an individual and indicate certain physiological characteristics. They serve in age distinction, sex distinction and stimulation, and in the care of young. 16. Specific odours of an animal's own or of foreign groups produce responses which vary with the animal's age.
Article
Asymmetries in both intrasexual competition and generation overlap occur in Antechinus (Dasyuridae; Marsupialia). We show that the range of interpopulation variation in the sex ratio of pouch young spans and exceeds the range of sex ratios at birth hitherto recorded from eutherians (Clutton-Brock and Albon 1983). Although postweaning dispersal and male mortality are similar among all Antechinus populations, interpopulation variance in female longevity leads to variable duration of mother/daughter interaction. As this duration increases, parental investment is increasingly biased toward males, supporting the view that local competition among female kin for resources may influence mammalian sex ratios.
Article
An investigation was made into the factors which lead to an elevation in plasma free cortisol concentration during the last weeks of life of males in natural populations of the red-tailed phascogale Phascogale calura. The dexamethasone suppression-test was employed to examine the glucocorticoid feedback control of plasma cortisol both before and during the breeding season.In both sexes ACTH alone or in combination with dexamethasone caused an elevation in the plasma concentration of cortisol, corticosterone and free cortisol. Dexamethasone administration in both males and females resulted in significant decreases in the plasma concentration of each of the glucocorticoid groups both before and during the first week of the breeding season (June and early July), however during the last week of breeding (late July) dexamethasone decreased the plasma glucocorticoid concentration of females but not of males. Administration of ACTH caused a significant elevation in the plasma cortisol concentration in all groups. However, the magnitude of this response diminished with time in both sexes.Dexamethasone treatment resulted in a decrease in the plasma testosterone concentration in males before and early in the breeding season however toward the end of breeding this effect was abolished.It is apparent that towards the end of the breeding season and during the last week of life of the males, glucocorticoid feedback control of ACTH is almost abolished. These changes, which occur only in the males late in the breeding season and near the time of their disappearance from the population, are consistent with a condition known as end organ resistance to steroid hormones.
Article
An investigation was made of endocrine changes occurring during the life history of Phascogale calura, a small, arboreal, squirrel-like insectivorous marsupial. Following a 3-week mating period in July each year, all males disappear from the population and it is presumed that they die. During the mating period the plasma cortisol concentration in males increased to a greater extent than did the plasma corticosterone. During this period the plasma concentration of CBG decreased in the males but not in the females, which resulted in competition between the two glucocorticoids for binding sites and a 25-fold sex difference in free cortisol concentration. The plasma testosterone concentration in males reached its maximum value about the time of disappearance of the males and the plasma lacked high-affinity binding for androgens. The depression in CBG concentration was androgen dependent since castration of captive males caused a marked increase in plasma CBG concentration which could be reversed with androgen administration. Postmorten examination of moribund males revealed evidence of hemorrhage from gastric ulcers and some evidence of immune suppression and disease. It is considered that a state of stress in males triggered by aggressive interactions following an elevation in plasma testosterone concentration during mating and antagonized by an androgen-dependent decrease in CBG concentration results in suppression of both immune and inflammatory reactions. This is the first detailed description of endocrine changes which accompany a stress-related total male mortality in a dasyurid marsupial species which does not belong to genus Antechinus.