Article

Lekking Behaviour in Crested Newts, Triturus cristatus

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Abstract

We describe the distribution of males and females in a natural population of crested newts, Triturus cristatus, during the breeding season and show that the mating system is a lek. Males arrived earlier than females at breeding sites, and throughout the breeding season there was a male-biased operational sex ratio. Males aggregated for most of the breeding season, and did not cluster over any resources essential for females. The male aggregations were not correlated with environmental factors, nor with female distribution. The males display to females prior to mating, but contribute nothing apart from sperm, and they cannot force females to mate. Females also aggregated, though less than males, and their aggregations were separate from those of males.

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... There are well-documented lek systems in insects, such as in drosophilid and tephritid fruit flies (for a complete list see [17]). In vertebrates, lek behavior is mostly reported from birds, where it has been documented from at least 148 species [18], while occasionally the behavior occurs also in amphibians (e.g., [19]), fish (e.g., [20]) and reptiles (e.g., [21]). In mammals, classic lek behavior appears to be rare and is found only in 12 species, mainly ungulates and pinnipeds, while 14 other species show a lek-like behavior that not fully matches the criteria mentioned above [22]. ...
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Centurio senex is an iconic bat characterized by a facial morphology deviating far from all other New World Leaf Nosed Bats (Phyllostomidae). The species has a bizarrely wrinkled face and lacks the characteristic nose leaf. Throughout its distribution from Mexico to Northern South America the species is most of the time rarely captured and only scarce information on its behavior and natural history is available. Centurio senex is frugivorous and one of the few bats documented to consume also hard seeds. Interestingly, the species shows a distinct sexual dimorphism: Adult males have more pronounced facial wrinkles than females and a fold of skin under the chin that can be raised in style of a face mask. We report the first observations on echolocation and mating behavior of Centurio senex, including synchronized audio and video recordings from an aggregation of males in Costa Rica. Over a period of 6 weeks we located a total of 53 perches, where during the first half of the night males were hanging with raised facial masks at a mean height of 2.35 m. Most of the time, the males moved just their wing tips, and spontaneously vocalized in the ultrasound range. Approaches of other individuals resulted in the perching male beating its wings and emitting a very loud, low frequency whistling call. Following such an encounter we recorded a copula-tion event. The observed aggregation of adult C. senex males is consistent with lek court-ship, a behavior described from only few other bat species.
... and density in males might be explained by the fact that males only provide sperm (no direct benefits 426 are provided; Hedlund & Robertson 1989, Hedlund 1990), resulting in their aggregation in ponds (i.e. 427 ...
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1. Understanding the mechanisms that regulate the dynamics of spatially structured populations (SSP) is a critical challenge for ecologists and conservation managers. Internal population processes such as births and deaths occur at a local level, while external processes such as dispersal take place at an inter-population level. At both levels, density dependence is expected to play a critical role. At a patch scale, demographic traits (e.g. survival, breeding success) and the population growth rate can be influenced by density either negatively (e.g. competition effect) or positively (e.g. Allee effects). At the scale of an SSP, although positive density-dependent dispersal has been widely reported, an increasing number of studies have highlighted negative density-dependent dispersal. 2. While many studies have investigated the effects of density on population growth or on dispersal, few have simultaneously examined density-dependent effects at the scale of both the local population and of the entire SSP. In this study, we examine how density is related to demographic processes at both the pond level (survival and population growth) and at the SSP level (between-pond dispersal) in a pond-breeding amphibian, the great crested newt (Triturus cristatus). The study was based on 20 years of individual capture–recapture (CR) data (from 1996–2015) gathered from an SSP made up of 12 experimental ponds (‘patches’). 3. We first used a CR multievent model to estimate both survival and dispersal rates in specific ponds as a function of distance between ponds. Then using a second CR multievent model, we examined whether survival and recapture rates were influenced by population density in a pond. Lastly, we used state-space time series models to investigate whether density affected population growth in each pond. 4. Our results found a positive density-dependent effect on survival and a negative density-dependent effect on departure. In addition, the findings indicate that population growth was negatively related to density in all 12 ponds. 5. These results support the hypothesis that in SSPs, density may have multiple and contrasting effects on demographic parameters and growth rates within local populations as well as on dispersal. This study underlines the need to better understand how density dependence may influence potential trade-offs between life-history strategies and life-history stages.
... As the breeding system is that of a lek, the males will generally be non-randomly distributed in the open areas of the pond for a prolonged time period as they display and await females for mating. The females spend less time in the lekking arena and following mating they venture in to surrounding vegetation to lay eggs, at which point they can become obscured and detection becomes inherently more difficult (Hedlund & Robertson, 1989). The peak detection time for all adults being earlier than that for males or females at 141 minutes after sunset (Fig. 3a) is counter-intuitive and may be an artifact of modelling. ...
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Amphibian populations have been shown to be in decline for the past four decades in part owing to habitat degradation and loss. In the United Kingdom, when faced by habitat works through development, consultant ecologists must undertake surveys for European protected species such as the great crested newt under licence following standardised guidance. However, previous studies and survey guidance present an unclear picture in reference to the ideal time of night to undertake sampling for this species. In this paper, an experimental review of the most effective times for detecting population sizes of great crested newts is presented. Sampling was undertaken at Scotland’s largest great crested newt population during the peak breeding season repeatedly between sunset and sunrise a total of six times. The results show a significant non-linear relationship between the relative detection rate of great crested newt populations over time with a peak of detectability at 141 minutes after sunset, and I propose that between 60-180 minutes following sunset is the best time to undertake surveys for this species. These data also show a significant peak of great crested newt presence at an air temperature of 3.5 °C which is below the reported critical minimum. However, water temperature which corresponded to peak newt presence was 10.4 °C suggesting this may be a crucial component of accurate great crested newt surveillance.
... Lekking behaviour has also been documented in other vertebrate taxa including amphibians (e.g. Hedlund & Robertson, 1989), fish (e.g. Clavijo, 1983) and reptiles (e.g. ...
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Bats (Mammalia: Chiroptera) are one of the most successful mammalian groups on Earth, and likely display the widest range of mating systems of all mammals. Despite this variety, one mating system appears to be underrepresented: lek breeding. Leks are characterised by aggregations of sexually-displaying males that are visited by receptive females for the sole purpose of fertilisation. To date only one bat species has been confirmed to breed using leks. In this study I investigate the possibility of lek breeding in a second bat species, the lesser short-tailed bat (Mystacina tuberculata) of New Zealand, using a variety of field and laboratory methods. Males in this species use “singing roosts” to sing during the breeding season, presumably to attract females. Through the use of radiotelemetry I show that females have large home ranges and dynamic roosting patterns. Through the use of video footage, spatial analyses, and passive-integrated transponder tags I confirm lek breeding in M. tuberculata; male singing roosts are aggregated spatially, are defended by males, and are visited by females for mating purposes. I also demonstrate that male singing roosts are aggregated around communal roosts used by the population, likely in response to the consistent high female densities in these areas. I analyse the characteristics of male songs and show that smaller males have higher song outputs than larger males. Furthermore, through the use of genetic analyses I show that smaller males have higher reproductive success than larger males, likely due to females selecting males with higher song outputs. Small size may permit males to expend less energy during their nightly activities, and thus they can expend more on courtship. Throughout the study I present many unique behaviours not described previously, including an alternative male strategy known as “timesharing” – multiple males sharing singing roosts. My results represent a useful description of sexual selection in a bat, as details of mating behaviour are known for only a fraction of bat species. I use my results to suggest conservation strategies for M. tuberculata, as well as to reexamine the apparent rarity of the mating system within the Order.
... The scarcity of reports of newts in mustelid diet, in particular that the otter, seems unusual considering that they occupy sympatric or parapatric habitat to anurans, which frequently occur in mustelid diet (Lode 1997, Sidorovich et al. 2007, Parry 2010. As with many amphibian species, newts aggregate for breeding (Hedlund and Robertson 1989), although these are less dense and subject to greater temporal variation than frogs and toads (Díaz-Paniagua 1992). Despite this, newts are a potential prey resource for mustelids such as the otter and that their availability will increase during the breeding season. ...
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Abstract-The remains of newts (Pleurodelinae) were recorded in Eurasian otter (Lutra lutra) spraints collected from two river systems on the Gower peninsula, Wales, U.K., between 2005 and 2007. Spraints were collected during detailed field surveys undertaken every two weeks as part of a two-year otter study. Palmate newt remains, mainly vertebrae and maxillae, were identified in 9.27% (43/464) of the spraints analysed by comparison with a reference collection of bones. This study demonstrates for the first time the extent to which otters may consume newts in the UK. Newt remains were recorded in spraints collected during all but two months (February and March) with the largest proportion of occurrences falling between April and July. Conservative estimates of the number of individuals consumed ranged between one and 31 newts per spraint. Newts represent a profitable prey for otters and, as with other amphibians, may represent a seasonally important dietary component with the newts becoming particularly vulnerable during reproductive accumulations. Sporadic but occasionally intense predation of newts by otters may affect both the breeding success and the dynamics of local newt populations. The presence of otters should be taken into consideration when planning conservation and translocation programs for newts. A photographic guide and morphological descriptions of amphibian remains is provided to aid future identification of amphibians in the diets of mammalian predators.
... Lekking behaviour has also been documented in other vertebrate taxa including amphibians (e.g. Hedlund & Robertson, 1989), fish (e.g. Clavijo, 1983) and reptiles (e.g. ...
Article
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Bats (Mammalia: Chiroptera) are among the most successful mammals and likely display the widest range of mating systems within the Class. One mating system that is underrepresented in the Chiroptera is lek breeding, which is characterized by aggregations of sexually displaying males that are visited by receptive females who appraise male displays and actively choose mates, yet receive no direct benefits such as assistance in parenting. Leks are thought to form when males can defend neither resources nor females, making it more economical to establish small breeding territories and self-advertise through sexual displays. Lekking is rare in mammals, and it has been suggested that a lack in the mobility required by females to economically seek out aggregations of sexually displaying males may explain this rarity. Bats, like birds, do not suffer reduced mobility and yet out of over a thousand described species, only one has been confirmed to breed in leks. We examine the rarity of lekking in bats by providing an overview on the current state of knowledge of their mating systems and discuss the ecological and social determinants for the observed trends, contrasted with the prerequisites of lek-breeding behaviour. We use the breeding behaviour of New Zealand's lesser short-tailed bat Mystacina tuberculata, which is believed to be a lek breeder, as a case study for the examination of potential lekking behaviour in bats, and highlight the importance of such research for the development of effective conservation strategies.
... We assumed simple life cycles with nonoverlapping generations and constant population sizes. Reproduction occurred by choosing randomly, for each offspring, one father and one mother from the parental generation with replacement (which amounts to a promiscuous mating system) and reiterating this process until reaching the carrying capacity (newts have often been described as lek breeding, and females are known to mate multiply; see, e.g., Rafinski 1981;Verrell and McCabe 1988;Hedlund and Robertson 1989;Halliday 1998;Jones et al. 2002aJones et al. , 2002bRafinski and Osikowski 2002). Y A Y A and Y B Y B were defined as lethal and removed after reproduction. ...
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Abstract Balanced lethal systems are more than biological curiosities: as theory predicts, they should quickly be eliminated through the joint forces of recombination and selection. That such systems might become fixed in natural populations poses a challenge to evolutionary theory. Here we address the case of a balanced lethal system fixed in crested newts and related species, which makes 50% of offspring die early in development. All adults are heteromorphic for chromosome pair 1. The two homologues (1A and 1B) have different recessive deleterious alleles fixed on a nonrecombining segment, so that heterozygotes are viable, while homozygotes are lethal. Given such a strong segregation load, how could autosomes stop recombining? We propose a role for a sex-chromosome turnover from pair 1 (putative ancestral sex chromosome) to pair 4 (currently active sex chromosome). Accordingly, 1A and 1B represent two variants (Y(A) and Y(B)) of the Y chromosome from an ancestral male-heterogametic system. We formalize a scenario in which turnovers are driven by sex ratio selection stemming from gene-environment interactions on sex determination. Individual-based simulations show that a balanced lethal system can be fixed with significant likelihood, provided the masculinizing allele on chromosome 4 appears after the elimination of the feminizing allele on chromosome 1. Our study illustrates how strikingly maladaptive traits might evolve through natural selection.
... In contrast, sex driven aggregation is possible. Hedlund & Robertson (1989) described lekking behaviour in the great crested newt T. cristatus, and Ho¨glund Ho¨glund & Alatalo (1995) suggested that most species of the genus Triturus mate in leks. In a lek, females could reduce the costs of mate detection (searching time, predation risk), by heading towards any conspecific, regardless of its sex. ...
Article
Although chemosignals are largely used in sexual communication in urodeles, olfactometer studies in newts provided contrasting results about the sex specificity of female behavioural responses. Because long-range sexual advertisement is believed to be costly, some species might restrain this activity to close interactions with conspecifics. We tested chemical-mediated sexual attraction in female palmate newt (Triturus helveticus) by measuring the attraction to male and female odours in a linear water olfactometer. Unexpectedly, females were attracted towards conspecifics regardless of sex. They did not show attraction towards Limnaea stagnalis, a common sympatric aquatic gastropod. These results do not support the use of long-range male sexual signalling in the palmate newt. Instead, conspecific attraction is likely to promote aggregation of males and females in breeding ponds. Observations in the field and in the laboratory tend to support the aggregative behaviour of this species. We discuss the possible function of conspecific attraction in this context. Heading towards any conspecific would increase the probability of finding potential mates. Chemical cues do not need to be sex-specific at that stage so that long-range sexual advertisement might be unnecessary. This work emphasizes the need for studies investigating the evolutionary relationships between sexual signalling systems and population-distribution patterns.
... In this study, the treatment effect on the latency to the first fanning event was not significant, suggesting that rather than beginning later, males reduce the time spent courting. In this and other newt species, sexual interference in nature is common and is mainly caused by males, which often end with the withdrawal of the female with no sperm transfer ( Verrell & McCabe, 1988;Hedlund & Robertson, 1989;Halliday, 1990;Mouta-Faria, 1995). Interestingly, field observations showed that male-to-male courtship interference occurs mainly during the males' display phase in L. boscai, and that interference was significantly less frequent in shorter sexual sequences ( Mouta-Faria, 1995). ...
... B.G. Svensson ans (Halliday and Verrell 1986; Hedlund and Robertson 1989), birds (Oring 1982; Avery 1984; Bradbury and Davies 1987), fish (Emlen and Oring 1977), insects (Brittain 1982; Thornhill and Alcock 1983; Alcock 1987) and mammals (Halliday 1983). One type of male courtship aggregation, the lek, is characterized by absence of paternal care, male territoriality on the lek, absence of resources for females in the territories and female freedom to choose among the males present (Bradbury 1977, 1981). ...
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Chapter
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Thesis
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DISSERTATION (Ph.D.)--THE UNIVERSITY OF MICHIGAN, Ann Arbor, MI. 1972, 570 pp. The courtship behavior of salamanders has fascinated naturalists for a long time. This fascination is not surprising for salamander courtship is so complex and elegant that it would delight any choreographer. Much of this extraordinary complexity is a consequence of the peculiar means by which insemination is accomplished in many salamanders. Rather than transferring sperm to the female directly by means of an intromittent organ, many salamander males attach a sperm bearing structure (the spermatophore) to the substrate. The female must then retrieve sperm mass with her vent. Before and during this process, the male runs, swims and leaps about the female and moves his body, limbs and tail in a bewildering variety of ways.
Article
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Chapter
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Article
Section I. Previous work has indicated that sage grouse Centrocercus wophasianus practice extreme polygyny (Simon 1940; Scott 1942; Patterson 1952; Lumsden 1968). The behavioural interactions that regulate this mating system have remained unclear, as the males' behaviour suggests both territoriality and dominance hierarchy. Section II. A basic difference between territorial and hierarchical social systems involves the extent to which the constituent individuals' relationships are polarized, rather than reciprocal. In a dominance hierarchy the interactions between individuals are polarized; territorial individuals typically interact reciprocally. Nevertheless, interactions among territorial individuals can incorporate two kinds of polarity: territorial dominance, as each individual dominates his neighbours inside his own territory but is subordinate to them in their territories; and polarized territoriality, when territorial individuals established in preferred areas prevent other territorial individuals from occupying these areas. The indications of reciprocity and polarity in the interactions of male sage grouse are investigated in this paper to clarify the expression of territoriality and dominance hierarchy in their social organization. Sections III to VI. Sage grouse gather for mating at communal display grounds, or leks, at traditional sites on sagebrush prairie. Although females arrive for mating primarily during 2 or 3 weeks in late March and April, males usually attend the leks regularly from February or March into May. Every morning and evening and often all night the males occupy small territories (13 to 100 m2) defined by boundary zones in which neighbours meet for facing-past encounters and wing-fighting (behaviour patterns are described in Section IV). Within their territories males repeatedly perform an elaborate, stereotyped display, the strut. I studied three leks with different numbers of attending males (154, 30 and 260), one lek each spring from 1967 to 1969. Time-lapse cinematography was used to record the males' positions and activities. Females congregate in dense packs at certain sites on a lek, usually in the same places on successive mornings. These sites, termed mating centres, also usually remain in the same locations in successive years. Section VII. Almost all copulations occurred at these mating centres, within the territories of one or two males, although as many as eighty other males occupied territories around each mating centre. Consequently, each year fewer than 10 per cent of the males completed more than 75 per cent of all copulations. Neighbours occasionally interrupt each other's copulations, but usually only those attempted near or within the boundary zone of facing-past encounters. Therefore, a male's success in mating does not depend on direct prevention of copulations by other males. Instead, a male becomes successful in mating by acquiring a territory at a mating centre. Section VIII. The behaviour of females arriving at a lek suggests how they might locate the mating centre. The possible cues associated with a mating centre are evaluated for their specificity in identifying the position of the mating centre and for their availability to the females. Although the behaviour of males near a mating centre differed in several respects from that of more peripheral males (for instance, the former strutted more persistently and engaged in much briefer and perhaps slightly more frequent facing-past encounters), these differences apparently depended mostly on the males' proximities to females, rather than on intrinsic differences among the individual males. Most males 2 or more years old, whether near a mating centre or not, responded similarly to the presence of females within their territories. Since a mating centre ordinarily has a traditional location within a lek, females might learn its position. Only limited guidance could come from the generally smaller territories of males near a mating centre. Section IX. Reciprocal interactions among males included the limited scope of neighbours' intrusions into each other's territories and neighbours' encounters as equals in boundary zones between their territories. Non-reciprocal, or polarized, relationships resulted from the attraction of males toward a mating centre. Since their more peripheral neighbours tended to encroach beyond their boundary zones, towards the females gathered at a mating centre, the more central males usually initiated most of the encounters with their more peripheral neighbours. The more central males also terminated most of their facing-past encounters, probably as a result of their tendencies to resume strutting nearer the females at the mating centre. When a territorial male disappeared, the vacancy was allocated to a more peripheral neighbour, one farther from the mating centre than the original occupant, without a noticeably increased frequency or intensity of antagonism. First-year males lag behind older males in the growth of their gonads (Eng 1963). Some yearlings eventually established territories around the edge of a lek about half-way through the mating period, but yearling males were never seen copulating. Section X. The combination of three processes can explain how a male acquires a territory at a mating centre: (a) the establishment of yearling males on territories around the periphery of a lek; (b) the centripetal movement of territorial males toward the mating centre as vacancies arise; and (c) the tendency for individual males to occupy positions in subsequent years at least as close to the mating centre as previously. The present study has provided evidence for the first two processes. Dalke et al. (1963) obtained some evidence that males usually return to the same lek and often to the same position in successive years. The hypothesis implies that a male's chances for success in mating would increase with increasing age. Section XI. To clarify the behavioural manifestations of territoriality in sage grouse, a distinction is made between the territorial resident's aggression gradient and his isolation gradient. Male sage grouse occupy largely exclusive territories. Their ability to dominate agonistic encounters declines steeply across a narrow boundary zone. However, these isolation and aggression gradients are not congruent. The shapes of both gradients depend on the interactions of the resident and his neighbours. Increased external pressure, owing to the attraction of males toward a mating centre, in conjunction with reduced internal resistance, owing to the central males' briefer facing-past encounters, could explain the generally smaller sizes of territories near a mating centre. The males' interactions, which include both reciprocal and polarized components, suggest polarized territoriality, a form of social organization that merges features from the classical paradigms of both territoriality and dominance hierarchies. Polarized territoriality generates the radially differentiated social structure on a lek. Section XII. A review of lek behaviour among grouse reveals only quantitative differences among the five species for which information on social organization is available. The lek behaviour of sage grouse represents the extreme development of this behaviour among grouse.
Article
The diets oftwo sympatric species of newts, Triturus vulgaris(L.) and T. cristatus(LAURENTI), from two localities in central Norway, have been compared. Adult T. vulgaris ate mainly those Cladocera which can be classified as planktonic, and to a lesser degree those which are predominantly benthic. The food of T. cristatus was predominantly benthic invertebrates and Cladocera associated with the bottom. T. vulgaris larvae ate planktonic - and predominantly benthic Cladocera, and to a certain degree also larger benthic invertebrates, while T. cristatus larvae (July-August) had taken almost exclusively Cladocera, 75% of which can be classified as planktonic. Large T. cristatus larvae (in September) had eaten relatively more benthic prey. These data would fit the hypothesis that the modes of feeding of the species are different: Adult T. vulgaris swim about in the water much of the time, while T. cristatus stay on the bottom. Among the young, T. vulgaris larvae are mainly associated with the bottom, while T. cristatus larvae are definitely more nektonic during most of the summer; large T. cristatus larvae, however, when nearing the time for metamorphosis, become benthic.
Article
The population ecology of newts was investigated between 1969 and 1974 in two localities near Gothenburg, SW Sweden: the Gunnebo park pond (about 300 m2) where Triturus cristatus Laurenti and T. vulgaris L. are sympatric, and a rock-pool (6 m2) in Billdal with only T. vulgaris. At Gunnebo, a population of about 350 breeding T. cristatus was found with about as many males as females but males being more aquatic than females. An annual survival of 0.7–0.8 was estimated for the adults. The T. vulgaris population at the same locality was estimated to about 250–300 breeding adults with a sex ratio possibly in favour of males. The survival of adults was found to be extremely low and a very small percent of the adults seems to breed more than once. The Billdal T. vulgaris population was estimated to contain nearly 70 breeding adults with a sex ratio very near to 1:1. The annual survival of adults was found to be 0.5. The different survival of the two T. vulgaris populations are discussed with particular reference to predation. The age at which newts breed for the first time seems to vary; for T. vulgaris five years may well be the normal age. Factors that may limit the sizes of the populations, possible reasons for differences in frequency of occurrence in water, and possible predators are discussed.
Article
The utilization of microhabitat and food resources by Triturus vulgaris and T. cristatus was studied in an upland pond in mid-Wales. From April to June T. vulgaris was more evenly distributed across the pond than T. cristatus, which showed a preference for the middle of the pond and the bottom of the water column. From July to September however, when most T. vulgaris had left the pond, T cristatus was evenly distributed within the water column and a much higher proportion was captured around the shorelines. Both species appear to be generalist predators with diets limited by prey size. Zooplankton were the most important prey for T. vulgaris, while leeches formed the bulk of the diet of T. cristatus. However, T. cristatus did not select larger-sized zooplankton than T. vulgaris. Large body size therefore enables T. cristatus to consume a wider range of prey sizes than T. vulgaris. Microhabitat niche overlap was greater than feeding niche overlap between the species.
Article
Calling assemblies of Hypsignathus monstrosus were studied for 17 months in the field to determine if they were “leks” or mating arenas. Direct observations, netting of animals at the assembly sites, and radio-tracking of both ♂♂ and ♀♀ at the assembly sites, foraging grounds, and day roosts were all utilized to make this determination. Captive animals were maintained to establish growth rates. It is concluded that Hypsignathus exhibit lek behavior even by the most conservative definition and share many features with other avian and mammalian lek species.
Article
and Summary1When a male smooth newt encounters a ♀ who is already engaged in courtship, he may mimic her behaviour during the spermatophore deposition and transfer stages of the courtship. He thereby usurps the courting ♂ and may inseminate the ♀ himself. Such sexual interference depresses the short-term, and perhaps long-term, mating success of the courting ♂.2In the presence of a potential rival, the courting ♂ alters certain aspects of his sexual behaviour. He displays more intensely to the ♀ and attempts to draw her away from the rival by increasing the duration of his display. He may also “check” that it is the ♀, and not the rival, who will elicit the deposition of a spermatophore from him. These changes in the behaviour of the courting ♂ are interpreted as defense against sexual interference.3Female smooth newts may be multiply inseminated as a consequence of sexual interference; this may result in sperm competition. However, ♀♀ seem to find competitive interactions between ♂ ♂ “aversive”.4Sexual interference by ♀-mimicry and associated defensive behaviour patterns are common in the urodele amphibians. Interference can be thought of as a “side-payment” conditional mating strategy.
Article
The mating system of the Carpenter bee, Xylocopa (Neoxylocopa) varipuncta Patton, closely resembles the leks of certain vertebrates. Males defend hovering stations at small creosote bushes on ridgetops in the Sonoran Desert, as well as at large ironwood trees in dry washes. Ridgetops, like washes, may provide orientation guides for dispersing females, channelling potential mates to waiting males. During the height of the two month flight season, both males and females were more concentrated on the ridge than in the wash. Males were particularly densely aggregated at or near two prominent peaks on the study ridge. At times, two or more males occupied the same creosote bush. Females visited hovering males infrequently, and exhibited a high degree of freedom in mate choice, usually rejecting males after a close inspection. The reduction in territorial intolerance exhibited by some males at ridgetop sites may occur: (1) because of the costs of repelling many intruders and (2) because females may choose among males through direct analysis of male phenotype, rather than by selecting a male on the basis of territory position.
Article
This paper extends previously published observations of the sexual behavior of the redspotted newt. In encounters between single males and females, the male either performs a brief lateral, or ‘hula’, display or clasps the female and holds her in amplexus for as long as 3 h. Experimental manipulation of the ambient sex ratio in an observation aquarium showed that the number of females available to a male did not influence his ‘decision’ whether to perform hula display or-attempt amplexus. In the presence of other males, a courting male showed a greater tendency to adopt the amplexus mode of courtship. Males interfered with one another's attempts to court and inseminate females. Unpaired males tried to displace those engaged in amplexus, but were seldom successful. During the spermatophore deposition and transfer stage of both courtship modes, unpaired males mimicked female behavior, apparently in order to obtain inseminations. Hula courtships were the most vulnerable to this type of competition; multiple insemination of the female was occasionally observed. The various costs and benefits associated with the various sexual strategies of male newts are discussed, together with some relevant ecological data. Similarly complex behavior in some other animals is also considered.
Article
1. The locomotor activity of European salamanders differs from species to species. At all stages of development Triturus vulgaris is more light-active, Salamandra salamandra is dark-active, while Triturus alpestris and cristatus occupy an intermediate position. 2. The activity of the larvae is high but the rhythm is not very pronounced. Triturus larvae are less dark-active than adults (Fig. 2). 3. Periodism disappears completely during metamorphosis but after some weeks of terrestrial life a diurnal rhythm reappears (Fig. 3). 4. Adults of Triturus species show an increased activity during their aquatic life in spring: they are active by day and night, maxima occurring in twilight or darkness. 5. Terrestrial adults leave their hiding places only during twilight or darkness. Triturus vulgaris and alpestris display locomotor activity in twilight only whereas Triturus cristatus and Salamandra salamandra are also active in the dark (Figs. 5, 6).
Article
The settlement of promiscuous males on sites where they are most likely to encounter females was examined by computer simulation. The study extended an earlier model of Parker (1978), which dealt with male settlement on environmentally fixed mating sites, to include populations of mobile females who can mate at any point in their home ranges. Males in the simulations were expected to settle at sites with high levels of female traffic (hotspots) and to correct for the sharing of females between adjacent sites. As a results, males became clustered into fewer and more compact aggregations as female home range size was increased. Increasing female density or allowing males to settle despotically instead of in a free manner had an opposite effect. The same results were found for both bounded and unbounded surfaces, although there was increased aggregation of males at the centre of bounded surfaces as female size was increased. The model may be relevant to the diversity of male dispersions seen in lek and swarm mating animals.
Is Tritwus mistatus territorial? In: Studies in Herpetology
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Migration and sexual selection in Ambystoma jeffrsonianurn Some methods for the statistical analysis of samples of benthic invertebrates Ecology, sexual selection and the evolution of mating systems
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Behavioural Ecology. An Evolutionary Approach
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