Article

Biology of antlers

Wiley
Journal of Zoology
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Abstract

Antlers are developed in 36 of the 40 species of deer. The shape of the antlers is characteristic of the species and the size varies allometrically with body size. In most species, antlers are produced only by males and grow at puberty. The antlers then undergo an annual cycle of calcification, cleaning, casting and regeneration. The successive sets of antlers developed by an individual increase in size and complexity in parallel with the increase in body size. Males continue to grow for at least half their life-span and are usually most successful in gaining access to females for mating when physically mature with large antlers. In reindeer/caribou Rangifer tarandus, both males and females grow antlers, and the growth and seasonal replacement of the antlers is not totally dependent on gonad activity, though gonadal hormones still act to synchronize the antler cycle with the seasonal reproductive cycle. Female reindeer use their antlers as weapons in intra-sexual competition and the main conflict occurs over access to food in winter. -from Author

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... In extant deer, the use of antlers as weapons during fighting to determine dominance is well documented between males of relatively equal size [11][12][13][14][15][16][17]. However, fighting risks serious injury and antler breakage [12,[15][16][17][18][19][20]. ...
... In extant deer, the use of antlers as weapons during fighting to determine dominance is well documented between males of relatively equal size [11][12][13][14][15][16][17]. However, fighting risks serious injury and antler breakage [12,[15][16][17][18][19][20]. Antler breakage can have a significant effect on future fighting ability and may cause bodily injury, which has the potential to increase predation risk [12,21]. ...
... Antler breakage can have a significant effect on future fighting ability and may cause bodily injury, which has the potential to increase predation risk [12,21]. When fighting occurs, the mechanics can be described in two stages: an initial clash and a pushing/twisting phase [12,15]. The initial clash involves a collision between the antlers of the two deer, requiring a capacity for the antler bone to resist impact loading. ...
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The largest antlers of any known deer species belonged to the extinct giant deer Megaloceros giganteus. It has been argued that their antlers were too large for use in fighting, instead being used only in ritualized displays to attract mates. Here, we used finite-element analysis to test whether the antlers of M. giganteus could have withstood forces generated during fighting. We compared the mechanical performance of antlers in M. giganteus with three extant deer species: red deer (Cervus elaphus), fallow deer (Dama dama) and elk (Alces alces). Von Mises stress results suggest that M. giganteus was capable of withstanding some fighting loads, provided that their antlers interlocked proximally, and that their antlers were best adapted for withstanding loads from twisting rather than pushing actions, as are other deer with palmate antlers. We conclude that fighting in M. giganteus was probably more constrained and predictable than in extant deer.
... Thus, Gruber [58] characterized antler casting as a process of "abacterial sequestration" of dead bone. It has been reported that the border between the dead antler and the living pedicle does not remain stable if antler casting is prevented by treatment of red deer stags carrying hard antlers with exogenous testosterone or oestrogen [59]. Instead, a "die-back" process down the pedicle and into the skull roof was described that could eventually be fatal. ...
... Many different functions of antlers have been proposed; however, it is generally agreed that they serve mainly as organs of display and for intraspecific fighting during the rut [32,101]. The antler cycle of male deer is tightly linked to their reproductive cycle, and the timing of the different events within this cycle is regulated by fluctuations in the blood levels of sex hormones, testosterone in particular [6,59,[102][103][104][105][106][107]. In cervid species inhabiting higher latitudes, the annual reproductive cycle itself is strictly controlled by the photoperiod [6,59,108]. ...
... The antler cycle of male deer is tightly linked to their reproductive cycle, and the timing of the different events within this cycle is regulated by fluctuations in the blood levels of sex hormones, testosterone in particular [6,59,[102][103][104][105][106][107]. In cervid species inhabiting higher latitudes, the annual reproductive cycle itself is strictly controlled by the photoperiod [6,59,108]. Antler growth occurs during a period of low circulating testosterone levels. ...
... There is practically no information about the reproductive aspects of white-tailed deer in the southern portion of their distribution. Like most mammals, variation in the species' reproductive chronology has been associated with latitude (Webb and Nellis 1981;Goss 1983;Verme and Ullrey 1984;Richter and Labisky 1985;Bronson 1989;Lincoln 1992;Loe et al. 2005). In tropical latitudes, the lack of change in day light should produce year-round reproduction in the whitetailed deer; nevertheless, reproduction is usually timed to coincide with resource availability (Heffelfinger 2011). ...
... Variation in the reproductive chronology of the white-tailed deer has been linked to environmental variables associated with latitude such as photoperiods and food availability (Goss 1983;Lincoln 1992;Price et al. 2005a;Demarais and Strickland 2011). The photoperiod acts through melatonin to modulate the secretion of reproductive hormones (mostly testosterone; Goldman 2001; Hanon et al. 2008), regulating the antlers cycle in this species (Price et al. 2005a(Price et al. , 2005b; however, in view of the slight photoperiodic changes in the tropics (and their weak temporal association with seasonal climatic changes), this environmental factor could have a reduced influence in controlling antler development in our study area. ...
... The photoperiod acts through melatonin to modulate the secretion of reproductive hormones (mostly testosterone; Goldman 2001; Hanon et al. 2008), regulating the antlers cycle in this species (Price et al. 2005a(Price et al. , 2005b; however, in view of the slight photoperiodic changes in the tropics (and their weak temporal association with seasonal climatic changes), this environmental factor could have a reduced influence in controlling antler development in our study area. This could mostly be happening because the development of the velvet antlers is taking place during February, when the duration of daylight increases, contrary to what occurs in high latitudes when the velvet antler stage is produced by the reduction in the day length (Goss 1983;Lincoln 1992). This situation suggests that in our study area, the conditions that determine the reproductive cycle of the species could be related to resource availability. ...
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Hunting activity in Mexico is regulated by the Secretaria de Medio Ambiente y Recursos Naturales (SEMARNAT), a Federal agency which also approves management plans and annual harvest rates. The official calendar for white-tailed deer hunting season in Mexico comprises a single season that runs from November to March. To determine the congruence of the current hunting calendar with the seasonal timing of hard antlers of white-tailed deer in the wetlands of Campeche in southeastern Mexico, we used data obtained from 10 camera trap surveys performed from 2010 to 2017. In the pictures of white-tailed deer, we identified the timing of the presence of different antler developmental stages (velvet, hard antlers, and no antlers) as well as the occurrence of fawns. We obtained 1071 pictures of deer with antlers in velvet stage, 128 with hard antlers, 16 with no antlers, and 414 pictures of fawns. We observed that pictures of deer with antlers in velvet stage occurred from February to July, hard antlers from May to October, and no antlers from the second part of November to January. We also observed that the fawning season ran from February to June. Our results indicate that the reproductive season in Campeche wetlands is different from what occurs in the northern latitudes of Mexico and southern USA. Because the timing of the white-tailed deer antler development in our study area does not coincide with the official hunting season established in Mexico, we believe it is necessary to modify the official hunting season for the Campeche wetland area. Sport hunting should be permitted from August to October, based on the timing of deer with hard antlers.
... The mesenchymal-epithelial interactions between the pedicle periosteum (PP), particularly the distal potentiated PP and the enveloping skin are vital for providing the niche for antler stem cells (Li et al., 2007). Deer antlers are male secondary sexual characters, and their growth is under the control of androgen hormones (Goss, 1968;Goss, 1983;Bubenik, 1990;Lincoln, 1992;Kolle et al., 1993;Suttie et al., 1995;Gaspar-López et al., 2010), although other growth factors are also pivotal in antler development. ...
... The role of androgens is well-defined, although the underlying mechanisms involving cellular interactions, androgen control of pedicle and antler development in vivo are complex and some aspects have not been satisfactorily explained in antler biology (Goss, 1968;Goss, 1983;Bubenik, 1990;Lincoln, 1992;Kolle et al., 1993;Suttie et al., 1995;Gaspar-López et al., 2010;Li and Chu, 2016). Pedicle growth is under the influence of increasing and elevated plasma testosterone (T) levels; conversely, declining T levels result in the transformation of the first antler from a fully-formed pedicle . ...
... The timing of antler casting and regrowth is tied to the reproductive cycle of species and is triggered by changes in hormone levels and, for individuals living in temperate climates, photoperiod [15][16][17] . By annually regrowing antlers, males develop honest signals of fighting ability that track age-specific changes in quality and status [18][19][20] . ...
... Therefore, we leveraged a much larger sample of wolf-killed adult (≥ 2 years old) male elk and compared the frequency of pedicled males in this sample with that in the male elk population at large. We evaluated wolves' preference for pedicled or antlered elk when pedicled individuals were rare (early March: 1-15 March) and increasingly common (late March: [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] in the population ( Supplementary Fig. 5). We measured use (that is, killed) and availability (that is, classified during surveys) of adult male elk with 216 detected wolf kills (n early = 103, n late = 113; Supplementary Fig. 6 We used these data to calculate preference ratios for pedicled and antlered elk. ...
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Sexually selected weapons evolved to maximize the individual reproductive success of males in many polygynous breeding species. Many weapons are also retained outside of reproductive periods for secondary reasons, but the importance of these secondary functions is poorly understood. Here we leveraged a unique opportunity from the predator-prey system in northern Yellowstone National Park, WY, USA to evaluate whether predation by a widespread, coursing predator (wolves) has influenced a specific weapon trait (antler retention time) in their primary cervid prey (elk). Male elk face a trade-off: individuals casting antlers early begin regrowth before other males, resulting in relatively larger antlers the following year, and thus greater reproductive success, as indicated by research with red deer. We show, however, that male elk that cast their antlers early are preferentially hunted and killed by wolves, despite early casters being in better nutritional condition than antlered individuals. Our results run counter to classic expectations of coursing predators preferring poorer-conditioned individuals, and in so doing, reveal an important secondary function for an exaggerated sexually selected weapon-predatory deterrence. We suggest this secondary function played a key evolutionary role in elk; uniquely among North American cervids, they retain their antlers long after they fulfil their primary role in reproduction.
... In contrast, if low-elevation migration was driven by predation risk, we expected low-altitude migrants to have lower exposure to predation than residents at high altitudes and constant selection for forage within their ranges, whereas selection within home range by residents would reflect tradeoffs in forage to avoid predation. Finally, because red deer are known to allocate more resources to maintain body size relative to the antler size when under unfavorable conditions (Lincoln 1992;Mysterud et al. 2005), we further used antler quality to assess the consequence of wintering in marginal habitats for red deer. If trade-offs in habitat selection of Mountains between 1997 and 2013 based on sightings in 18 hunting grounds in the area. ...
... The relatively short migration distances (6-10 km, Kropil et al. 2015) minimized the cost of movement. However, limited access to forage resources in winter can affect the body condition of deer, which may prioritize allocation to somatic growth over antler growth (Lincoln 1992;Mysterud et al. 2005). Because migrant and resident deer had similar summer range characteristics as well as selection within summer ranges, and age structure was not different among samples, we suggest that the reduced antler quality observed in deer wintering in marginal low-altitude habitats may result from poorer nutrition in winter because the majority of red deer in Carpathians shed their antlers in February and March while migrate to high altitudes in May . ...
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Resource selection by ungulates is driven by trade-offs between foraging and predation avoidance or by intraspecific competition. Ungulates use migratory flexibility to optimize access to spatially and temporally variable resources across seasons, sometimes even adaptively switching between migrant or resident strategy as conditions change. After an 80% increase in red deer (Cervus elaphus) population and simultaneous recovery of wolves (Canis lupus) in the Kremnica Mountains, Slovakia, a significant portion of the deer population started to migrate downhill (< 700 m) to marginal habitats during winter. Building on available spatial data on forage availability, predation risk and deer abundance, we tested for differences in habitat selection of migrant and resident male red deer to assess possible reasons for this change. On high-altitude (700–1100 m) summer ranges deer were not forced to trade-off forage to avoid predation within their home ranges. However, during winter, residents remaining on high-altitude ranges selected for areas with highly abundant forage only under low predation risk or at high deer abundance. Downhill migration exposed migrants to 15% lower forage availability but simultaneously reduced wolf predation risk by 39% relative to residents. Consequently, the limited access to forage resources at low altitude ranges have reduced antler growth, especially in young males. Our study represents one of few that address the role of predation risk in driving seasonal migrations in temperate systems where snow is not likely to be the major driver of migration to low-altitude winter ranges.
... Antlers of cervids seem to be well suited to studies of fluctuating asymmetry. Not only are these secondary sexual characters important in intrasexual competition (Clutton-Brock 1982;Goss 1983;Lincoln 1992), dominance (Bowyer 1986;Lincoln 1972), and possibly mate choice (Bartoš and Bahbouh 2006;Ditchkoff et al. 2001a;Kruuk et al. 2002;Lincoln 1992), but also rapid development of antlers (Goss 1983) should make them particularly sensitive to stress (Watson and Thornhill 1994). Swaddle and Witter (1997) suggested that rapid growth might prohibit compensational growth feedback between sides of a bilateral trait, thereby making it even more difficult for an individual to produce symmetrical traits. ...
... Antlers of cervids seem to be well suited to studies of fluctuating asymmetry. Not only are these secondary sexual characters important in intrasexual competition (Clutton-Brock 1982;Goss 1983;Lincoln 1992), dominance (Bowyer 1986;Lincoln 1972), and possibly mate choice (Bartoš and Bahbouh 2006;Ditchkoff et al. 2001a;Kruuk et al. 2002;Lincoln 1992), but also rapid development of antlers (Goss 1983) should make them particularly sensitive to stress (Watson and Thornhill 1994). Swaddle and Witter (1997) suggested that rapid growth might prohibit compensational growth feedback between sides of a bilateral trait, thereby making it even more difficult for an individual to produce symmetrical traits. ...
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Fluctuating asymmetry, random departure from perfect symmetry in bilateral traits, has been proposed as an indirect indicator of individual quality. Sexually selected traits, such as deer antlers, are hypothesized to demonstrate decreasing level of fluctuating asymmetry with increasing trait size and decreasing level of fluctuating asymmetry with increasing age. These hypotheses have been previously tested for antlers using linear measurements to quantify fluctuating asymmetry. However, antlers are complex, 3-dimensional traits making it difficult to quantify all forms of visual asymmetry using traditional, linear measurements. It is this visual asymmetry that would be assessed by potential mates and rivals. Therefore, we created 3-dimensional computer models of white-tailed deer (Odocoileus virginianus) antlers to measure visual fluctuating asymmetry. Asymmetry measures of various antler traits were computed using the models by measuring distances from the trait to a vertical and horizontal plane created using coordinate points generated within the model. We found no association between degree of fluctuating asymmetry and trait size, nor was any association found between degree of fluctuating asymmetry and age using either the 3-dimensional measures of asymmetry or traditional, linear measures of asymmetry. Examination of these data suggests that fluctuating asymmetry of white-tailed deer antlers is not a reliable indicator of quality.
... deer antlers or widowbird tails; Andersson, 1994). Exaggerated traits have long been thought to be costly, driving many sex-specific behavioral and physiological processes (Andersson, 1994;Emlen, 2001;Lincoln, 1992). Further, the expression of these exaggerated traits is often hypersensitive to organismal condition, defined as the pool of resources allocable to traits (Cotton et al., 2004;Rowe and Houle, 1996). ...
... Agedriven shifts were predicted to be more pronounced in males as they began developing exaggerated traits. Third, because exaggerated male sexual traits are presumed to be large resource sinks (Lincoln, 1992;Andersson, 1994;Emlen, 2001), we hypothesized that biomass allocation to these traits would be greater than that to similar non-sexual traits. Finally, we hypothesized that variation in P availability would induce greater plasticity in biomass allocation toward sexual traits compared to non-sexual traits. ...
Article
Although sexually dimorphic traits are often well studied, we know little about sex-specific resource use strategies that should underlie such dimorphism. We measured sex-specific responses in acquisition and assimilation of two fundamental resources, carbon (C) and phosphorus (P) in juvenile and mature Hyalella amphipods given low and high supplies of inorganic phosphate, analogous to oligotrophic and eutrophic conditions, respectively. Additionally, we quantified allocation of resources to sexual traits in males. Dual radiotracer ((14)C and (33)P) assays revealed substantial age- and sex-specific differences in acquisition and assimilation. Furthermore, a phenotypic manipulation experiment revealed that amphipods fed low-P food allocated more C to all traits than those fed high-P food. Importantly, we found that amphipods preferentially allocated more C to the development of a sexually selected trait (the posterior gnathopod), compared to a serially homologous trait (the fifth pereopod) not under sexual selection. Substantial differences in how the sexes use fundamental resources, and the impact of altered nutrient supply on such differences illuminate sexual dimorphism at the lowest level of biological organization. Such information will be important in understanding how sex- and age-specific life history demands influence nutrient processing in a biosphere characterized by rapidly changing alterations to biogeochemical cycles.
... Remarkably, these structures, composed predominantly of primary osteons, can weigh several kilograms per individual (Chen et al., 2009;Picavet and Balligand, 2016). Their specific use by deer (weapon and shield) is associated with particular mechanical properties namely a lesser stiffness but a higher fatigue resistance compared to skeletal bone (Clutton-Brock, 1982;Geist, 1966;Leslie Jr and Jenkins, 1985;Lincoln, 1992). Antlers can undergo high impact loading and large bending moments without fracture (Blob and Snelgrove, 2006). ...
Article
Antlers are bony structures composed predominantly of primary osteons with unique mechanical properties due to their specific use by deer as weapon and shield. Antler bone fracture resistance has attracted prior scrutiny through experimental tests and theoretical models. To characterize antler mechanical properties, compression of cubes, or bending or tensioning of rectangular bars have been performed in the literature with variations in the protocols precluding comparisons of the data. Compression testing is a widely used experimental technique for determining the mechanical properties of specimens excised from cortical or cancellous regions of bone. However, the recommended geometry for compression tests is the cylinder, being more representative of the real performances of the material. The purpose of research was to report data for compressive strength and stiffness of antler cortical bone following current guidelines. Cylinders (n = 296) of dry antler cortical bone from either the main beam or the tines of Cervus elaphus, Rangifer tarandus, Cervus nippon and Dama dama were tested. This study highlights the fact that compression of antler cortical bone cylinders following current guidelines is feasible but not applicable in all species. Standardization of the testing protocols could help to compare data from the literature. This study also confirms that sample localization has no effect on the mechanical properties, that sample density has a significant impact and allows enriching the knowledge of the mechanical properties of dry antler cortical bone.
... They are cast off after the rut each year and grow back during the following spring: antlers have one of the quickest growth rates in the animal kingdom (Goss, 1983). Their specific use by deers (as a weapon and shield) is associated with particular mechanical properties, namely reduced stiffness but higher fatigue resistance compared to skeletal bone (Clutton-Brock, 1982;Geist, 1966;Leslie Jr and Jenkins, 1985;Lincoln, 1992). As captive red deer (Cervus elaphus) are already raised in high numbers in different parts of western Europe for their meat and hides, antler is a readily available biomaterial that does not imply the killing of the carrier. ...
Article
Availability of graft materials to fill up osseous defects has always been a concern in orthopaedic surgeries. Deer antler material is a primary bone structure that is easy to collect and could serve as a xenograft. This study examines the behaviour of red deer antler trabecular cylinders in critical size distal femoral epiphyseal defects in 11 rabbits, and evaluates the effect of the decellularization protocols. Two preparation regimes (A and B) were used, with and without lipids and proteins. Radiographs were taken immediately after surgery and after euthanasia 12 weeks post-implantation. Histological evaluation was performed on non-decalcified 10-μm sections with a van Gieson picro-fuchsin staining protocol. A region of interest was defined for each histological section, evaluating the inflammatory reaction, the fibrosis process, and the osteogenesis. Each histological section was microradiographed to evaluate bone contact, presence of synostosis, remodelling and ossification processes. All antler cylinders were successfully implanted. Final radiographic analysis demonstrated osteointegration of most implants at various stages. Light to moderate inflammation around the grafts was noted with only one case showing full encapsulation. A variable degree of intimacy between implant and host bone was evidenced, with bone remodelling and osteogenesis of various intensity being present in all implanted sites. No differences were found between group A and B. Removal of lipids and proteins in the grafts surprisingly did not seem to matter. Decellularization and sterilization protocols may be advocated. Although it presents several limitations, this study shows some promising results regarding antler trabecular bone osteointegration.
... These exaggerated sexually selected structures are more sensitive to nutritional history and the physiological state of the organism than are other body structures and, as a result, they are thought to be honest signals of individual quality [4,[6][7][8]. Exaggerated sexually selected weapons therefore may be used as both signals-to assess rival males or to attract choosy females-and as tools of combat [5,[9][10][11][12][13][14]. ...
Article
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Japanese rhinoceros beetle (Trypoxylus dichotomus) males have exaggerated head horns that they use as weapons in combat over reproductive opportunities. In these contests, there is an advantage to having a longer horn, and there seems to be little cost to horn exaggeration. However, populations vary in the amount of horn exaggeration across this widespread species. Here, we examine four populations and quantify scaling and functional morphology of the horn. We then measure force production by the horn system in a combat-relevant movement. We find that not only does horn length vary among populations, but allometry of lever mechanics and force production varies in a complex way. For instance, some beetle populations make relatively long horns, but exert relatively low forces. Other populations make shorter horns and produce higher forces during fights. We suggest that this performance variation could be associated with differences in the intensity or type of sexual selection across the species.
... However, these higher levels were not significant. Variations in testosterone secretion may occur because of gonadotrophic hormones, which are influenced by environmental factors, especially in temperate climate species that have marked seasonality (Bubenick & Bubenick, 1987;Lincoln, 1992). ...
Article
The fallow deer (Dama dama) is a species of Cervidae commonly kept in captivity, either in commercial farms or in zoos. The reproductive seasonality of this species is well known in the northern hemisphere, where photoperiod is a decisive factor in androgenic activity and, consequently, in the development of secondary sexual characteristics among male adults. The maintenance of this species in tropical regions has been successful, but there are no studies that demonstrate the maintenance of reproductive seasonality under these climatic conditions, which was the objective of the present study. To do so, the present investigation involved 27 fallow deer (D. dama) specimens, of which 14 were adults and 13 prepubescent (<8 months) individuals, all assessed during and outside (December–February) the reproductive season (June–August). The serum concentrations of testosterone, testicular volume, and neck circumference were analyzed among all animals during both seasons. The reproductive season was marked by expressive hormonal concentrations, increasing neck circumference and testicular volume, differing significantly between adults and prepubescent individuals outside the season. Positive correlations were observed among all analyzed variables: mean testicular volume and neck circumference (r = 0.92, p < 0.0001), testicular volume and testosterone concentrations (r = 0.79, p < 0.0001) and between neck circumference and testosterone concentrations (r = 0.67, p < 0.0001). Given the results found, the conclusion is that even under tropical climate conditions the reproductive seasonality of the fallow deer is well defined and may be related to photoperiod.
... The antler cycle is closely linked to the testicular cycle and the associated seasonal fluctuations in androgen secretion in male deer (Price et al. 2005, Ramesh et al. 2013. Antler growth occurs during the period of low testosterone concentration, whereas antler mineralization and velvet shedding from antlers are spurred by increasing testosterone levels and corresponding increase in mating activity (Lincoln 1992, Bubenik 2006. Casting of antlers is triggered by a marked decline in testosterone levels, which can occur at various rates, depending on the sex ratio within the respective population. ...
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ABSTRACT The aim of this study was to determine the seasonal activity patterns and asynchrony between different antler stages in male axis deer from the Mediterranean island of Rab in Croatia using camera traps. Nine cameras with an infrared motion detection system were used to track animal activity over a 12-month period, 24 hours per day. Stags were divided into two categories of antler development: regeneration stage and hard antler stage. The frequency of detection of each category in the photographs allowed us to investigate seasonal activity patterns. To describe the seasonal activity pattern in each category, we fitted the segmented linear regression and predicted that the ratio of monthly activity of stags in the two antler categories would interchange regularly during the research period. Over the 12-month study period, 36,862 photographs were analysed. A significant difference in frequency was found between the two antler categories (P<0.01), with a consistently greater presence of hard-antlered stags. The highest frequency of detection of both antler categories was found in the winter season, and the lowest in spring. The segmented linear regression clearly distinguished three break points in April, June and December in the hard antler stage, with a significant difference in activity pattern among the months for each slope. On the other hand, no significant difference was found for the regeneration stage. Therefore, the expected proportional interchange in the number of stags in the two antler stages throughout the year did not occur. This study revealed that the Mediterranean axis deer population showed a unique activity pattern, where antler stage may act as a possible driver regulating stag movements.
... antler production). The first antler growth begins when a deer approaches puberty (G omez et al. 2006) and is characterised by pedicle initiation, followed by antler development, velvet cleaning and antler casting (Lincoln 1992). VA and its derivatives, retinoic acids (RAs), were shown to be a potential endogenous morphogen during antler growth. ...
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The present study examined the effects of dietary vitamin A (VA) on antioxidant functions, immune functions and production performance in farmed sika deer. Forty healthy male sika deer (initial body weight (BW): 47.07 ± 4.75 kg; 8 months of age) were randomly assigned to four treatments on the basis of BW. The dietary treatments included a basal diet (containing 330 U/kg VA) supplemented with 0 (control), 2500, 5000 or 10,000 U/kg retinol acetate (500,000 U/g, Rovimix A500, Roche, Basel, Switzerland). The results showed that deer fed a diet supplemented with 5000 U/kg VA had higher (p <.05) average daily gains and gain:feed values than those from the control group. VA supplementation significantly increased (p <.05) glutathione peroxidase and superoxide dismutase activities and total antioxidant capacity and decreased (p <.05) the concentrations of reactive oxygen species in the serum. Additionally, serum immunoglobulin A, interleukin-2 and soluble CD8 were significantly increased (p <.05) when dietary VA supplementation was increased from 0 to 5000 U/kg. However, a high dose of VA supplementation (10,000 U/kg) caused decreased (p <.05) concentrations of serum tumour necrosis factor-α and interleukin-1. Deer that received feed supplemented with 5000 U/kg VA had higher (p <.05) dry antler yield than the control deer. The present results indicated that VA supplementation improved growth performance, antioxidant functions, immune functions and dry antler yield. Taken together, the suitable level of VA supplementation was found to be 5000 U/kg (total VA content 5330 mg/kg dry matter) for male sika deer during the first antler growth period. © 2019, © 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
... Horns are made of keratin, like your fingernails (more accurately they consist of a bony core and a keratinized sheath), they grow throughout the entire lifetime of an animal and they are permanent and are never shaded, Antlers, on the other hand, are made of bone and they are shaded every year and in the fall, a whole new set grows back in time for the mating season. The antler cycle is regulated by the testicular cycle [1,2]. Horns consist of a covering of keratin (and some other proteins) surrounding a core of live bone. ...
Article
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Many people use the terms horns and antlers inter- changeably. They both grow from an animal’s forehead and both are used for the assertion of dominance, providing de- fence and attracting the mates.
... Horns are made of keratin, like your fingernails (more accurately they consist of a bony core and a keratinized sheath), they grow throughout the entire lifetime of an animal and they are permanent and are never shaded, Antlers, on the other hand, are made of bone and they are shaded every year and in the fall, a whole new set grows back in time for the mating season. The antler cycle is regulated by the testicular cycle [1,2]. Horns consist of a covering of keratin (and some other proteins) surrounding a core of live bone. ...
Article
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The horn of the saiga antelope is often used in Traditional Chinese medicine (TCM). Its “popular” name in Chinese is ‘Lin Yan Jiao’ and the pharmaceutical name is Cornu Antelopis. It is as famous and valuable as musk, pilose antler (Lurong) and rhino horn, the most-renowned medicinal materials of animal origin used in TCM. However, the saiga has also joined the rhinoceros on the list of endangered species. The presented review briefly overviews an existing knowledge regarding the biologically active compounds at saiga horn. The main beneficial effects of the horn, which could be described in scientific terms, are mostly antipyretic and antiulcerative. Despite some indication of its efficacy, no specific compound from the saiga horn has yet been isolated or scientifically described. It can be assumed that the amino acid composition of the horns of various animals: the buffalo, the saiga, the ox and the goat is almost same in terms of nature and composition when they differ only in their ratios. The similarity of amino acid and peptide compounds has confirmed the similarity of anti-inflammatory and antiulcerative physiological actions. Thus, we can talk about the interchanging ability of horns. If someone believes in the positive influence of animal horns on human health, we can thoroughly recommend the use of horns from animals that are more abundant (such as water buffalo, rams) as compared to the critically endangered species such as saiga (or rhinoceros) with possible similar effect on the organism. There are also some evidences that the antipyretic effect is not strictly dependent on the origin of the horn and might be connected to the herbal substances prescribed and used in the preparation of Chinese medicine. However, only some thorough scientific research on TCM could provide new results that can identify the most active components of the extract and confirm our assumptions about the beneficial effects of extracts or powders of the horns.
... Horns are made of keratin, like your fingernails (more accurately they consist of a bony core and a keratinized sheath), they grow throughout the entire lifetime of an animal and they are permanent and are never shaded, Antlers, on the other hand, are made of bone and they are shaded every year and in the fall, a whole new set grows back in time for the mating season. The antler cycle is regulated by the testicular cycle [1,2]. Horns consist of a covering of keratin (and some other proteins) surrounding a core of live bone. ...
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The horn of the saiga antelope is often used in Traditional Chinese medicine (TCM). Its " popular " name in Chinese is 'Lin Yan Jiao' and the pharmaceutical name is Cornu Antelopis. It is as famous and valuable as musk, pilose antler (Lurong) and rhino horn, the most-renowned medicinal materials of animal origin used in TCM. However, the saiga has also joined the rhinoceros on the list of endangered species. The presented review briefly overviews an existing knowledge regarding the biologically active compounds at saiga horn. The main beneficial effects of the horn, which could be described in scientific terms, are mostly anti-pyretic and antiulcerative. Despite some indication of its efficacy, no specific compound from the saiga horn has yet been isolated or scientifically described. It can be assumed that the amino acid composition of the horns of various animals: the buffalo, the saiga, the ox and the goat is almost same in terms of nature and composition when they differ only in their ratios. The similarity of amino acid and peptide compounds has confirmed the similarity of anti-inflammatory and antiulcerative physiological actions. Thus, we can talk about the interchanging ability of horns. If someone believes in the positive influence of animal horns on human health, we can thoroughly recommend the use of horns from animals that are more abundant (such as water buffalo, rams) as compared to the critically endangered species such as saiga (or rhinoceros) with possible similar effect on the organism. There are also some evidences that the antipyretic effect is not strictly dependent on the origin of the horn and might be connected to the herbal substances prescribed and used in the preparation of Chinese medicine. However, only some thorough scientific research on TCM could provide new results that can identify the most active components of the extract and confirm our assumptions about the beneficial effects of extracts or powders of the horns.
... The antlers are cast off after the rut each year, and, for most species, grow during spring: they have one of the quickest organ growth rates among all animal species (Goss 1983). The specific use of this bone tissue (as a weapon and shield) is associated with atypical mechanical properties compared to skeletal bone (Geist 1966;Lincoln 1992;Clutton-Brock 1982;Leslie and Jenkins 1985). The aim of this work is to review the antlers' mechanical properties from different species of Cervidae (deer, roe deer, fallow deer, reindeer, moose, elk etc.); the point of interest is to identify biomaterial with properties that would make it usable in veterinary orthopedics. ...
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There is a resurgence of interest in the study of deer antlers. Recent research advocates their potential for use in bone xenografts. Using this working hypothesis, we can formulate many questions: do antlers really present unique or interesting mechanical properties, and if so, which factors affect these properties? Many other issues, including tissue compatibility, could be discussed; however, this article will focus on the biomechanical features of antlers. This paper reviews some answers found within current published material, and could help determine the optimal selection of some antlers for further experimental studies and clinical trials. Some general elements like anatomy and histology of deer antlers are briefly summarised. This paper will attempt to define the fundamental differences between skeletal bone and antler bone in terms of their organic and mechanical properties. We will then compare the previously published data, which details the mechanical properties of antlers from different species of Cervidae, by reviewing several aspects such as: sex; geographical situation; morphology; hydration state; and mineral composition. Some findings emerge: mechanical properties do not vary with gender or latitude, and the most important determining factor appears to be the species, alongside morphology and use of antlers. The state of hydration and mineral composition also has an influence on the mechanical properties of Cervidae antlers.
... Sexually dimorphic traits-both ornaments and armaments-are supported by testosterone in many vertebrates (e.g., Lincoln, 1971Lincoln, , 1992Whiting et al., 2003;B okony et al., 2008). Such traits can increase mating success, but also incur energetic costs, and sometimes decrease survival (Promislow, 1992. ...
... Sexually dimorphic traits-both ornaments and armaments-are supported by testosterone in many vertebrates (e.g., Lincoln, 1971Lincoln, , 1992Whiting et al., 2003;B okony et al., 2008). Such traits can increase mating success, but also incur energetic costs, and sometimes decrease survival (Promislow, 1992. ...
... The fact that antlers of the Vietnamese sika deer (C. nippon pseudaxis) are structurally and mechanically more similar to those of Père David's deer (Elaphurus davidianus) than to those of the Siberian wapiti does not suggest that those characteristics are related to phylogeny (Hernandez-Fernandez & Vrba 2005), even if closely related species frequently show similarities in the basic external structure of the antler (Lincoln, 1992). It seems easier to explain why some of these variables co-vary together than to explain why these differences among species appeared. ...
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Antlers are costly structures produced annually by male cervids using minerals obtained from their diet and from resorption of their skeleton. Availability and nutritive quality of food resources therefore have a great impact on the investment of males in these secondary sexual traits. We studied the structure, mineral composition and mechanical quality of antlers of the Siberian wapiti (Cervus canadensis Sibiricus), Père David's deer (Elaphurus davidianus) and Vietnamese sika deer (Cervus nippon pseudaxis), three closely-related cervid species. The three herds investigated were maintained under the same feeding and management conditions (one male per herd) throughout a 3-year study period. We showed that there was no significant inter-specific difference in antler composition of the three species under the same feeding regime. However, mechanical properties varied between the Siberian wapiti and the other two species; and structural characteristics were different among all of them. Our results show that antler composition has a similar chemical profile across species when grown under the same feeding regime whereas the internal structure and mechanical properties appear to be species dependent.
... The allometric relationship between antler and body size in the family Cervidae has been repeatedly demonstrated (Huxley 1931;Gould 1973;Clutton-Brock et al. 1980;Lincoln 1992;Plard et al. 2011), but recently it has been proposed that it have a quadratic rather than the traditionally assumed linear relationship (Lemaître et al. 2014). Most studies explained this allometric relationship as an evolutionary consequence of sexual selection and specially male-male competition (Clutton-Brock et al. 1980;Plard et al. 2011;Lemaître et al. 2014; also Bro-Jørgensen 2007 for bovids). ...
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The evolution of the investment in exaggerated secondary sexual traits is a topic of great interest for scientists. Despite antlers in the family Cervidae being one of the most interesting allometric structures, the nature of the relationships between antler and body size, and the influence of physiological factors driving the evolution of these characters, still remain unclear. In this paper, I examine these relationships in depth using the largest sample size ever studied (43 species). Under the hypothesis that antler growth may be limited by skeleton size as this process requires the allocation of huge amounts of mineral resources to the antlers, skeleton-related variables may more accurately explain these allometric relationships. The existence of physiological constraints should therefore be more clearly highlighted when studying the relationships between body size variables and the relative investment in the antler (measured as length or mass of antler per kg of skeleton). Results show that antler length is best described as being linearly related to head-body length rather than other measurements of size, and antler weight has a quadratic relationship with body mass. However, the relative investment in antler length (related to skeleton mass) is independent of body size variables, while the relative investment in antler mass has a quadratic relationship with shoulder height. The results obtained for antler mass reflect the existence of physiological constraints in the evolution of antlers, which are greater for larger sized species. On the other hand, the evolution of antler length may be linked to other factors, most probably sociobiological and biomechanical ones.
... 2004, Mitchell i dr. 1976, Lincoln 1992, Thomas i dr. 2004 ...
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Habitat is defined as a set of natural resources and conditions present in a given area that ensures the stability of the population that it inhabits. Antlers of Cervidae family are an example of fast growing tissues and the only organs of the mammals capable of complete regeneration. Each year the antlers are discarded and each year the new set of antlers are grown. This is called a cycle of antler growth and it is closely associated with the reproductive cycle, hormonal processes, climate and hydrological factors. Climatic and hydrological factors can influence directly through air temperature, precipitation (rain, snow), ground cover (rain, snow), sunlight hours (photoperiod) and hydro levels. Climatic and hydrological factors can influence indirectly through vegetation as a source of food. The aim of this paper is to link climate and hydological factors with the developement level of red deer antlers. The research area is periodically flooded parts near the rivers of Danube and Drava and it lies in the northeastern part of Republic of Croatia, on the border with Hungary and Serbia. At this unique natural areas one can find habitats for many species of plants and animals and it also represents an preserved habitat of red deer (Cervus elaphus). The study lasted for six hunting years - from 2004/2005. to 2009/2010. For this current study the data were taken from middle aged and mature stags (five and more years old). Total of 382 stags were measured. The value of antlers were observed through the following traits of red deer antlers: antler weight, total lenght of branches, lenght of tird tine and the number of tines. Hunting year 2007/2008. showed values of observed characteristics significantly higher than hunting years of 2004/2005., 2005/2006. and 2006/2007, as compared to hunting year of 2008/2009. and 2009/2010. observed values were not significantly higher but they were higer and that is in a biological sense equally important. The management measures were the same throught the years of research. Hydrological report showed that regular spring flooding of the Danube river failed in year 2007. and that was not the case during the other years of research. It would be normal that the average monthly temperature during the coldest months for this habitat was below zero but during the end of 2006. (November and December) and in the beginning of 2007. (Januar and Februar) the average temperature was from 2,9 to 8,4 degrees C above zero. That was the maximum temperature during the winter in 10 year period and that was winter with the least number of cold days (<0,0 degrees C) (35 days during these four months). Rainfall in the firs three monts of 2007. were slightly above average (142 1) but during April and May the level of rain was up to three time lower in the relation to the other years of research. Number of days with snow was only two days during the coldest months of 2006. and 2007. and the height of snow cover for this two days was 1 cm. In the first five months during 2007. there were more sunshine hours than in other years of research, especially during the month of April when the growth and developement of antlers is most intense. Based on the results presented in the text above the values of measured antler traits were highest in huntig year 2007/2008. and that was because of extremely favorable climatic and hydrological conditions in a significant time for antler growth and developement. The results from this research can be a guidance for future prediction of red deer antler developement in a sence of creating management measures.
... Sexually dimorphic traits-both ornaments and armaments-are supported by testosterone in many vertebrates (e.g., Lincoln, 1971Lincoln, , 1992Whiting et al., 2003;B okony et al., 2008). Such traits can increase mating success, but also incur energetic costs, and sometimes decrease survival (Promislow, 1992. ...
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Testosterone supports male reproduction through a broad range of behavioral and physiological effects, including the maintenance of sexually dimorphic muscle used in male-male competition. Although it is often assumed that a persistent relationship exists between men's testosterone production and musculature, most studies either fail to find evidence for such a relationship, or document very weak associations. In nonhuman primates, by contrast, correlations between testosterone and muscle mass are higher. Here, we propose the "Paternal Provisioning Hypothesis," which predicts that men's skeletal muscle is less dependent on the effects of androgens than that of other primates, and more sensitive to the physical demands of men's work. This permits human fathers to downregulate testosterone, which has negative impacts on pair-bonding and parenting effort, but without sacrificing the strength and musculature necessary to provision mates and offspring. We tested predictions of the Paternal Provisioning Hypothesis by assessing parental status, salivary testosterone levels, anthropometry, and strength among 122 men (ages 18-78) at the Mogielica Human Ecology Study Site in rural Poland. We chose this population because men practice subsistence agriculture, regularly engaging in physically demanding labor. Grip and chest strength were assessed using a dynamometer, and upper-body musculature was estimated from arm muscle circumference. In this population, testosterone showed no association with measures of strength or musculature, and was lower in older men and pair-bonded fathers. Marital and parental status and workload, by contrast, were positive predictors of muscle mass and strength measures. These findings offer support for the Paternal Provisioning Hypothesis. Am J Phys Anthropol, 2015. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.
... Unlike antler metrics of harvested deer, cast antlers may provide an unbiased description of a population's antler characteristics (Ditchkoff et al. 2000). Deer shed (Michael 1965;Behrend and McDowell 1967) or cast their antlers (Ditchkoff et al. 2000) each spring when testosterone levels drop and blood supply is cut off from the antler base (Lincoln 1992;Rolf and Enderle 1999). Currently, baseline cast-antler data exist for Iberian red deer Cervus elaphus hispanicus in Spain (Fierro et al. 2002) and deer within a controlled hunting area in Oklahoma (Ditchkoff et al. 2000). ...
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Deer antler metrics have been used to index the physical condition of deer populations, but those sampled at deer-check stations may not be representative of the population at large if deer hunters select for larger antlered individuals. The objectives of this study were to 1) evaluate whether white-tailed deer Odocoileus virginianus hunters exhibit selective behavior through an age-specific comparison of harvested antler metrics to naturally cast antlers; and 2) evaluate the potential value of cast antlers to monitor herd condition via antler seal depth to identify individual health. Antler metrics representing antler mass (main beam basal circumference), length (main beam length), and the number of antler points were taken on yearling (aged 1.5 y) hunter-harvested deer during the 2009, 2010, and 2011 November firearm seasons and compared with freshly cast yearling antlers collected during the corresponding 2010, 2011, and 2012 antler-casting seasons. The antler metric indicative of antler mass was greater in harvested deer than the deer herd at large, providing empirical evidence of size-selective hunter behavior. We suggest that cast antlers be used as a less-biased alternative to measurements taken of antlers of harvested deer to assess herd characteristics.
... In this study, evidence for a positive correlation between I s and selection differentials was limited, although the same ecological factors affecting I s were weakly correlated with selection on rut start dates. Rut start dates in males are strongly correlated with antler cleaning dates (the end of the growth period for antlers) and so are likely to be influenced by condition , Moyes et al. 2010, Lincoln 1992. We have found that under high competition (many immigrant males rutting), selection is stronger on rut start dates when females are more synchronous. ...
Article
Although sexual selection in nature has been studied intensively, much is still unknown about the evolution of mating systems in wild populations: for example, how male competition and female choice interact, or the effect of environmental heterogeneity on selection. Further, important questions remain about the consequences of sexual selection for genetic structuring and genetic variation within populations. In this thesis, I investigate the causes and consequences of sexual selection in a polygynous mammal, the red deer Cervus elaphus. This species is characterized by high male reproductive skew resulting from competition to defend harems of females. Here however, I present evidence for previously unappreciated complexity in the mating system, in terms of female mating behaviour and environmental influences on male-male competition. I then go on to investigate the consequences of non-random mating on co-ancestry and inbreeding in the population. Finally, I investigate methods for separating genetic and environmental sources of covariance between individuals. Specifically, I: (i) Show a surprising degree of female mobility during the breeding season (the 'rut‘). Around 40% of females change harem when in oestrus and almost half of these movements result in paternity for the novel male; however I show that these movements are unlikely to be explained by female choice for mates. (ii) Reveal that variance in male mating success is affected by variation in ecological parameters, in particular the interaction between the number of immigrant males in the rutting population and the temporal synchrony of females. (iii) Demonstrate substantial inter-individual differences in the plasticity of acoustic signals produced by rutting males with changes in social context. (iv) Reveal the existence in this population of three rarely reported mating behaviours in polygynous mammals. I find around a fifth of females mate with the same male in multiple years; female relatives frequently mate with the same male; and males rut in locations close to their relatives. Further, I show these behaviours are associated with higher co-ancestry and inbreeding in the population than expected under random mating. (v) Finally, I investigate how spatial associations between relatives upwardly bias estimates of heritability in four phenotypic traits. I do this by accounting for shared environment effects in animal models by i) inclusion of spatial autocorrelation parameters and ii) a novel multi-matrix approach.
... The roles of such large antlers have been discussed (Barnosky, 1985;Stuart et al., 2004;Benton and Harper, 2009). Antlers in cervids, including giant deer, are used for display and for combat between males seeking to establish territories (Barnosky, 1985;Benton and Harper, 2009), and are also employed when males compete for dominance and access to females in the rut (e.g., Lincoln, 1992). 2 The seminal study of the antlers of giant deer, specifically concerning their positive allometry, was performed by Gould (1974). ...
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We evaluated the skull of an ancient giant deer with a deformity of one antler. The skull was found in the 1930s in the San River near Barycz, in southeastern Poland. Its dating (39,800±1000 yr BP) corresponds to MIS-3, when the giant deer was widespread in Europe. Our diagnostics for the antler included gross morphology, radiography, computed tomography, and histopathology. We noted signs of fracture healing of the affected antler, including disordered arrangement of lamellae, absence of osteons, and numerous Volkmann’s canals remaining after blood vessel loss. The antler deformity appears to be of traumatic origin, with a healing component. No similar evaluation process has been described previously for this species.
... Moreover, it should be considered that antlers probably evolved first as a sexual secondary trait related to sexual selection (Bubenik 2002). In agreement with what has been reported for most deer species: males grow for at least half of their life-span (Lincoln 1992). In white-tailed deer males reach maturity one year later than females (Strickland & Demarais 2000). ...
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As in many deer species antler weight is related to body weight, our aims were to determine if in male pampas deer, an endangered species, antler size is related to body size in single-age class groups of males, and if antler and body weight, and their ratio, differ between adult and young males. Data were collected during two consecutive years in two groups of semicaptive males, composed by 6 adult males and 5 young males. All males had free access to food, and were weighed both during March (autumn in southern hemisphere). Data regarding antler status were registered daily: when a buck was observed without its antlers we searched the paddock for the antler, collected and identified it. Antler weight, volume, and lengths were recorded, and density was calculated. There was a positive relationship between body weight and antler weight in adults but not in young males. Body weight, antler weight, and antler weight: body weight ratio were greater in adult than young males. Antler volume, coronet circumferences, and lengths of first and second tines were greater in adult than young males. Overall, we concluded that in pampas deer managed in semicaptive conditions, with free access to food and a low range of variation of body weight there is a positive relationship between body weight and antler mass only when males reach their adult weight. Also, antler weight and size, as well as the antler:body weight ratio is greater in adult males than in males younger than 3 years old. Both differences reflect a slow development rate considering high food availability.
... The roles of such large antlers have been discussed (Barnosky, 1985;Stuart et al., 2004;Benton and Harper, 2009). Antlers in cervids, including giant deer, are used for display and for combat between males seeking to establish territories (Barnosky, 1985;Benton and Harper, 2009), and are also employed when males compete for dominance and access to females in the rut (e.g., Lincoln, 1992). 2 The seminal study of the antlers of giant deer, specifically concerning their positive allometry, was performed by Gould (1974). ...
Article
Full-text available
We evaluated the skull of an ancient giant deer with a deformity of one antler. The skull was found in the 1930s in the San River near Barycz, in southeastern Poland. Its dating (39,800±1000 yr BP) corresponds to MIS-3, when the giant deer was widespread in Europe. Our diagnostics for the antler included gross morphology, radiography, computed tomography, and histopathology. We noted signs of fracture healing of the affected antler, including disordered arrangement of lamellae, absence of osteons, and numerous Volkmann’s canals remaining after blood vessel loss. The antler deformity appears to be of traumatic origin, with a healing component. No similar evaluation process has been described previously for this species.
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Evolutionary biology is poised for a third major synthesis. The first presented Darwin's evidence from natural history. The second incorporated genetic mechanisms. The third will be based on energy and biophysical processes. It should include the equal fitness paradigm (EFP), which quantifies how organisms convert biomass into surviving offspring. Natural selection tends to maximise energetic fitness, E=PcohGFQ$$ E={P}_{\mathrm{coh}}\mathrm{GFQ} $$, wherePcoh$$ {P}_{\mathrm{coh}} $$ is mass‐specific rate of cohort biomass production, G$$ G $$ is generation time, F$$ F $$ is fraction of cohort production that is passed to surviving offspring, and Q$$ Q $$ is energy density of biomas. At steady state, parents replace themselves with offspring of equal mass‐specific energy content, E$$ E $$ ≈ 22.4 kJ/g, and biomass, M$$ M $$ ≈ 1 g/g. The EFP highlights: (i) the energetic basis of survival and reproduction; (ii) how natural selection acts directly on the parameters of M$$ M $$; (iii) why there is no inherent intrinsic fitness advantage for higher metabolic power, ontogenetic or population growth rate, fecundity, longevity, or resource use efficiency; and (iv) the role of energy in animals with a variety of life histories. Underlying the spectacular diversity of living things is pervasive similarity in how energy is acquired from the environment and used to leave descendants offspring in future generations.
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Understanding how fecal glucocorticoid (GC) concentration is associated with reproduction in wild animals allows us to associate physiological stress with the costs of reproduction. Glucocorticoids are among the main stress‐related hormones, and their secretion is strongly associated with reproductive seasonality. Using non‐invasive methods (thereby avoiding causing stress), we used fecal GC metabolites (FGC) to test the hypothesis that the reproductive phase (mating, non‐mating, gestation, and lactation) influences stress levels of the seasonally reproductive Pampas Deer (Ozotoceros bezoarticus). Furthermore, we compared FGC between sexes and between males of different antler statuses (velvet, hard, cast). During 1 year, in the Pantanal of Brazil, we collected 621 fresh fecal samples (327 from females, 294 from males) from which we estimated FGC using enzyme immunoassay (EIA). FGC concentrations varied by reproductive phase and antler status. Agonistic and courtship interactions associated with mating (i.e., fights between males, attempts to mount females), suggest that they influence FGC concentrations most strongly in both sexes. Females also had greater FGC concentrations during lactation, suggesting that this phase and parental care are also associated with increased physiological stress. In males, the association of FGC concentrations with antler status may be, in part, associated with photoperiod and testosterone secretion, both of which can trigger reproductive and agonistic behaviors. Finally, reproductive synchrony of the sexes causes similar FGC over time and suggests that environmental factors contribute as well. We show that non‐invasive monitoring of glucocorticoid metabolites levels is an effective tool for detecting changes in the physiological stress response in Pampas Deer, suggesting that this tool will be useful for detecting changes in physiological stress caused by human disturbance, such as cattle ranching in Pantanal and similar disturbances elsewhere.
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Annual antler growth begins in the spring and is completed by late summer for male caribou ( Rangifer tarandus groenlandicus ) from the Qamanirjuaq herd (Nunavut, Canada), aligned with both the spring migration and a seasonal dietary shift. Antlers may provide a non‐lethal means of studying short‐ and long‐term changes in caribou ecology through incorporated isotopes of carbon (δ ¹³ C) and nitrogen (δ ¹⁵ N). We sampled the antlers of 12 male caribou from the Qamanirjuaq herd culled in September 1967. We predicted that serial sampling of antlers would reflect the known seasonal dietary change from lichen to grass‐like and shrub diet based on rumen contents from individuals culled during the same period. The δ ¹³ C and δ ¹⁵ N were analyzed in food sources and every 3 cm along each antler's length. The carbon isotope compositions of collagen (δ ¹³ C col ) varied by ~0.5‰ among individuals and within antlers, while the carbon isotope compositions of antler bioapatite (δ ¹³ C CO3 ) increased by 1–1.5‰ from pedicle to tip. Values of δ ¹⁵ N col increased within antlers by 1–3‰ from pedicle to tip and varied by 3‰ among the individuals sampled. Antler collagen was lower in δ ¹⁵ N col by ~1‰ relative to bone collagen. Bayesian mixing models were conducted to test for changes in dietary proportions from antler isotope compositions. Mixing models did not indicate significant dietary shifts for any individual during antler formation, showing consistently mixed diets of fungi, horsetail, lichen, and woody plants. Increases in δ ¹⁵ N col in antler tissue could, therefore, correspond to subtle seasonal dietary changes and/or the physiological stress of antler tissue development.
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We analyzed pedicle bone from roe bucks that had died around antler casting or shortly before or during the rutting period. Pedicles obtained around antler casting were highly porous and showed signs of intense osteoclastic activity that had caused the formation of an abscission line. Following the detachment of the antler plus a portion of pedicle bone, osteoclastic activity in the pedicles continued for some time, and new bone was deposited onto the separation plane of the pedicle stump, leading to partial pedicle restoration. Pedicles obtained around the rutting period were compact structures. The newly formed, often very large secondary osteons, which had filled the resorption cavities, exhibited a lower mineral density than the persisting older bone. The middle zones of the lamellar infilling frequently showed hypomineralized lamellae and enlarged osteocyte lacunae. This indicates a deficiency in mineral elements during the formation of these zones that occurred along with peak antler mineralization. We suggest that growing antlers and compacting pedicles compete for mineral elements, with the rapidly growing antlers being the more effective sinks. The competition between the two simultaneously mineralizing structures is probably more severe in Capreolus capreolus than in other cervids. This is because roe bucks regrow their antlers during late autumn and winter, a period of limited food and associated mineral supply. The pedicle is a heavily remodeled bone structure with distinct seasonal variation in porosity. Pedicle remodeling differs in several aspects from the normal bone remodeling process in the mammalian skeleton.
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In some species, sexual selection is stronger in females than males. In classically polyandrous birds, for instance, females compete for mating opportunities and males care for offspring. Sex steroids such as testosterone have been suggested to regulate the behaviours of 'role-reversed' females and males, but comparative studies did not find evidence for a role of testosterone in relation to sex roles. However, the large variability of hormone measurements across laboratories may prevent detecting subtle differences in hormone levels. To circumvent this caveat, I compared sex steroid concentrations of females and males of two closely related and cohabiting species with different mating systems: the classically polyandrous black coucal (Centropus grillii) and the monogamous white-browed coucal (C. superciliosus). Baseline and gonadotropin-releasing hormone (GnRH)-induced testosterone concentrations were twice as high in female black coucals than female white-browed coucals, and the low pre-breeding progesterone concentrations of female black coucals were consistent with progesterone's modulatory role during agonistic interactions in this species. Baseline and GnRH-induced testosterone and progesterone concentrations did not differ between males of both species. This study provides first evidence that elevated testosterone is associated with sex-role-reversed traits in females, whereas low levels of testosterone may not be necessary to facilitate sex-role reversal in males.
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Three FA indices showed correlations with age and magnitude of traits, but not in general. Significant correlations between magnitude of traits and their FA were more pronounced in AFA (12 traits) than in RFA (10 traits) in all age classes except yearlings. For the tray tine form (curvature), FA significantly correlated with its magnitude in young, middle-aged and ripe stags, which indicates that the trait is a reliable indicator of asymmetry. Significant differences in AFA among age classes were found in four traits (weight of dry antlers, volume of antlers, distal circumference of beams and total length of crown tines). By RFA, a significant difference among age classes was only found for the distal circumference of beams. Thus, AFA is a more vulnerable condition index. Contrary to other research findings, developmental instability was more pronounced in older age classes. In yearlings, no significant FA dependence on the trait of antler size was detected, but in certain traits, an asymmetry detected at an early age remains visible later as well, although in stags grown under relatively optimal (especially trophic) environment conditions, developmental instability was present anyway. This proposes two hypotheses for further research: Competition may be manifested even under controlled conditions, which might jeopardize the developmental stability of certain individuals, or some traits will show developmental instability regardless of relatively good environmental conditions.
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A study of horn growth characteristics of sable antelope in South Africa investigated the environmental effects of sex, calving year and season on horn development for animals up to 50 months old. Horn growth characteristics were assessed in the age categories of 0 to 15, 15.1 to 36, and 36.1 to 50 months. The growth rate (cm/day) of horn length differed significantly between male and female sable antelope in all age categories. The horns of males grew by 0.89 cm/day and females by 0.68 cm/day between 0 and 15 months. Between 15 and 36 months, horn growth was 0.079 cm/day for males and 0.042 cm/day for females. Between 36 and 50 months horn growth was 0.044 cm/day for males and 0.015 cm/day for females. The base circumference differed significantly between the sexes only between 0 and 15 months, when it was 0.026 cm for males and 0.014 cm for females. The number of horn rings did not differ between sexes. Thus, there was rapid initial growth for both males and females, with the horn growth of females slowing noticeably once they reached sexual maturity. Supplemental feeding regimes introduced on most farms affected horn growth traits positively, resulting in longer horns at maturity.
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The periodically detached and regenerated antlers are a diagnostic trait of deer (family Cervidae) and represent the most rapidly growing bones of mammals. During their species-specific and seasonally fixed growth period of a few months, antlers can accumulate large amounts of ‘bone-seeking’ elements that are incorporated into the bone mineral. This makes antlers ‘naturally standardised’ environmental samples that can be used to monitor environmental pollution of deer habitats by these elements. The present contribution reviews studies utilising hard antlers as environmental archives to reconstruct temporal and spatial variation of contaminant levels in different geographic regions. We further discuss the use of lead isotope signatures in antlers for source apportionment of environmental lead and the impact of excess fluoride uptake on antler mineralisation. In addition, promising areas for future research using antlers as bioindicators are discussed.
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Antlers are the most conspicuous trait of cervids and have been used in the past to establish a classification of their fossil and living representatives. Since the availability of molecular data, morphological characters have generally become less important for phylogenetic reconstructions. In recent years, however, the appreciation of morphological characters has increased, and they are now more frequently used in addition to molecular data to reconstruct the evolutionary history of cervids. A persistent challenge when using antler traits in deer systematics is finding a consensus on the homology of structures. Here, we review early and recent attempts to homologize antler structures and objections to this approach, compare and evaluate recent advances on antler homologies, and critically discuss these different views in order to offer a basis for further scientific exchange on the topic. We further present some developmental aspects of antler branching patterns and discuss their potential for reconstructing cervid systematics. The use of heterogeneous data for reconstructing phylogenies has resulted in partly conflicting hypotheses on the systematic position of certain cervid species, on which we also elaborate here. We address current discussions on the use of different molecular markers in cervid systematics and the question whether antler morphology and molecular data can provide a consistent picture on the evolutionary history of cervids. In this context, special attention is given to the antler morphology and the systematic position of the enigmatic Pere David's deer (Elaphurus davidianus).
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Antlers are paired deciduous bony cranial appendages of deer that undergo a regular cycle of growth, death and casting, and constitute the most rapidly growing bones in mammals. Antler growth occurs in an appositional mode and involves a modified form of endochondral ossification. In endochondral bones, calcified cartilage is typically a transient tissue that is eventually completely replaced by bone tissue. We studied the distribution and characteristics of calcified cartilage in hard antlers from three deer species (Capreolus capreolus, Cervus elaphus, Dama dama), i.e., in antlers from which the skin (velvet) had been shed. Remnants of calcified cartilage were regularly present as part of the trabecular framework in the late formed, distal antler portions in all three species, whereas this tissue was largely or completely missing in the more proximal antler portions. The presence of calcified cartilage remnants in the distal antler portions is attributed to the limited antler lifespan of only a few months, which is also the reason for the virtual lack of bone remodeling in antlers. The calcified cartilage matrix was more highly mineralized than the antler bone matrix. Mineralized deposits were observed in some chondrocyte lacunae and occasionally also in osteocyte lacunae, a phenomenon that has not previously been reported in antlers. Using synchrotron radiation-induced X-ray fluorescence (SR-XRF) mapping, we further demonstrated increased zinc concentrations in cement lines, along the inner borders of incompletely formed primary osteons, along the walls of partly or completely mineral-occluded chondrocyte and osteocyte lacunae, and in intralacunar mineralized deposits. The present study demonstrates that antlers are a promising model for studying the mineralization of cartilage and bone matrices and the formation of mineralized deposits in chondrocyte and osteocyte lacunae.
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Acteocemas, a very poorly documented early Miocene stem-cervid, is one of the first ruminants bearing antler-like appendages, which has provided a ground for discussion on the origin of antlers. We describe a new and very complete appendage from the site of Sant Andreu de la Barca (Spain) together with some other unpublished specimens from the nearby Costablanca attributed to Acteocemas aff. infans, compare with fossils from elsewhere in Europe (including the A. infans holotype), and perform micro-CT scans. The findings provide new empirical data that Acteocemas protoantlers were able to be cast and re-grown. However, microstructural analyses suggest that the protoantler lifespan could be longer than that of modern antlers, preventing it from assuming a similar cycle. Results support that increased seasonality associated with a drop in global temperatures played a role in the origin of antler regeneration, and that deciduousness (through bone shedding) was an efficient way for (male)deer to reduce the seasonal leftover of bone mass. The early evolution of deciduousness, as in the probable irregular protoanter cycle of Acteocemas, was limited by the warming ca. 17–15 Ma, whereas the emergence of antlers with coronet was concomitant with the second increase in seasonality associated to the cooling ca. 15–13 Ma.
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Antlers are periodically regenerated paired cranial appendages of male deer (both sexes in reindeer) that constitute the fastest-growing bones in the animal kingdom. The annual antler cycle of male deer is linked to testicular activity and largely controlled by seasonal fluctuations of testosterone concentrations in their blood. We studied the effects of an experimental doubling (to eight months) of the velvet antler phase, during which the antlers are covered by skin (velvet), on the histomorphology of antler bone in three adult fallow bucks. Extension of the velvet antler phase in the experimental animals had been caused by administration of the antiandrogen cyproterone acetate (CPA). The distal portions of the antlers from two of the CPA-treated bucks exhibited partial sequestration of the antler cortex, with the separation plane typically located along the border between cortex and spongiosa. It is hypothesized that this was caused by cortical necrosis due to severe ischemia during later stages of the extended velvet antler phase. In places, new cancellous bone had been deposited on the resorption surface of the spongiosa, indicating a regeneration process. Normal fallow deer antlers (“controls”) from this and a previous study, that is, antlers with a timespan of about four months between onset of new antler growth and velvet shedding, exhibited no or only minor bone remodeling and still contained remnants of calcified cartilage in their distal portions. In contrast, the antlers of the three CPA-treated bucks showed evidence (secondary osteons and resorption cavities) of marked bone remodeling along their entire length and lacked remnants of calcified cartilage. Our results underscore that the typical histological features of antler bone reflect its short-lived nature. Antlers are not mechanically loaded during the velvet stage, and it is presently unclear what triggered remodeling activity in the antlers whose lifespan had been experimentally extended.
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We analyzed the lead content in antlers of 90 adult European roe bucks (Capreolus capreolus) that had been culled between 1901 and 2019 in an agricultural-dominated hunting district in Lower Saxony (Northern Germany). Antler lead values ranged between 0.2 and 10.9 mg/kg dry weight. Median lead concentration was highest after World War II, during a period (1956–1984) of rapidly increasing mass motorization and use of leaded gasoline. Lead levels in antlers decreased markedly after the phase-out of leaded gasoline, but high values were still found in some recently collected antlers. This could indicate persistent lead pollution from former use of lead additives to gasoline, other traffic-related sources, or from agricultural sources (e.g., sewage sludge, fertilizers). This study highlights the suitability of analyzing roe deer antlers for the historical monitoring of changing lead levels in the environment. By collecting antlers and providing them for study, local hunters can significantly contribute to environmental surveillance and the monitoring of environmental pollution by bone-seeking contaminants.
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Males usually compete to gain access to prospective mates. Through this male–male competition, superior males have a higher chance of passing on their traits to the next generation of male offspring. One category of male traits is armaments, which are weapons used during competition, for example, the chelae of fiddler crabs and the antlers of deer. One consequence of intrasexual selection is the exaggerated evolution of armaments, which can be limited by trade‐offs, such as trade‐offs with male body size. Here, we formulate a game‐theoretic sexual selection model to explore the exaggerated evolution of armaments through male–male competition. The model is used to determine how competition affects the evolution of an armament that is subject to trade‐offs. Our simulation can be used to support the exaggerated evolution hypothesis, that is, male–male competition escalates the rate of evolution of armaments. Here, we formulate a game‐theoretic sexual selection model to explore the exaggerated evolution of armaments through male–male competition. The model is used to determine how competition affects the evolution of an armament that is subject to trade‐offs. Our simulation can be used to support the exaggerated evolution hypothesis, that is, male–male competition escalates the rate of evolution of armaments.
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This paper reports a case of delayed velvet shedding and bilateral premature antler casting above the coronets in a young adult red deer stag from Germany. Based on the established role of testosterone in the control of the antler cycle, the antler abnormality is considered to have been the result of a (temporary) androgen deficiency. The basal surfaces (separation planes or seals) of the cast antlers were markedly concave. Scanning electron microscopy revealed that the separation plane was densely covered with Howship's lacunae, denoting intense osteoclastic activity along the border between the proximal (living) and distal (dead) antler portions. Our observations and those of previous studies indicate that antler casting does not occur at a pre‐determined separation plane, but along the border between living and dead bone, regardless of the position of this border within the cranial appendages. This is a major difference to autotomy of (living) appendages at fixed breakage planes, as it occurs for instance in lizard tails.
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Developmental stability of an individual is often evaluated by means of fluctuating asymmetry (FA) in bilaterally paired morphological characters. Even though FA has been widely investigated in ungulates, its connection with the condition of individuals and their environment is still debated. In this study we investigated factors contributing to FA in horn length in the sexually monomorphic Alpine chamois. We measured right and left horn length of 1682 Alpine chamois (Nfemales = 734; Nmales = 948) shot during 2 consecutive hunting seasons (2015 and 2016) in 7 neighbouring districts in Central-Eastern Alps (Italy). We found no consistent left or right bias. Within our study population, FA values were normally distributed around a mean value that was not significantly different from zero (Skewness = − 0.107, SE = 0.06; Kurtosis = − 0.055, SE = 0.119). We also found that absolute FA in horn length was affected by environmental and climatic conditions experienced by the individuals during their first year and half of life. Statistically significant differences between right and left horn length were found with higher local population density and lower forage quality (i.e., siliceous substrate). Moreover, snow cover duration during the individuals’ first winter increased horn length asymmetry. No individual characteristics played a role in promoting horn length asymmetry. The associations between exposure to stressors and deviations from bilateral symmetry suggest that absolute FA can be used to identify populations whose individuals experienced stressful conditions early in life. We found in this relatively monomorphic species that both male and female horns were equally affected by climate, substrate, and local population density, thus showing that large male secondary sexual characters, such as the antlers of deer stags, are not the only traits which can be influenced by a negative environment and exhibit increasing FA.
Thesis
The white-tailed deer is the most hunted species in the tropics of Mexico. However, information on daily movements, the size of the home environment, as well as the seasonality of antlers and times of birth in tropical sites is scarce. In this study we analyzed the factors that influence the daily distances travelled, the size of the home environment and the temporality of antlers and fawning of the white-tailed deer distributed in southeastern Mexico between the states of Tabasco and Campeche. Using satellite telemetry data, daily movement data were obtained, as well as the area of deer activity. Using trap camera data, the timing of antlers and the time of fawning of white-tailed deer were analyzed. We found that the daily movements of the white-tailed deer in the study area are less than reports from studies in central and northern Mexico. Movements recorded are longer during the dry season and shorter during the wet season. Similarly, the home environment recorded in this study was similar to that recorded in other tropical sites for the species but differs from home environments recorded in sites where animals were translocated or reintroduced. Physical factors such as temperature did not show any influence on daily movements, but food scarcity is likely to include the time of birth, as well as longer daily movements of deer. In addition, the results indicate that the breeding season in the Campeche wetlands is different from that in the northern latitudes of Mexico and the southern United States. It was found that the timing of the development of hard white-tailed deer antlers in the study area does not coincide with the official hunting season established in Mexico.
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Objectives Relative to industrialized populations, men from subsistence groups exhibit lower testosterone values and more modest declines with age. Limited energy availability has been hypothesized to suppress testosterone production, particularly during young adulthood when testosterone levels are highest, resulting in a flatter trajectory of age-decline. Energetic constraint, however, is not unique to the evolutionary ecology of humans, and yet significant age-related testosterone decline is observed in numerous species of wild primates. Conversely, human life history is distinguished by extensive bi-parental care and male provisioning. Because fathers show decreased testosterone with parenting effort, we argue that within more naturalistic and evolutionarily relevant ecologies, natural fertility and earlier reproduction suppresses testosterone in emerging adulthood such that a lower relative baseline dictates less age-decline across the remaining lifespan. Methods We examine men’s testosterone levels as contrasting functions of energetic status and paternal involvement across three traditional populations with substantial variability in men’s nutritional condition and parental investment. Anthropometric and demographic data along with saliva samples were collected from 70 Datoga, 29 Hadza, and 43 Qom men, ages 20–72 years. Results Population variation in salivary testosterone was greatest at younger ages and patterned so paternal involvement associated with lower morning and evening testosterone, along with diminished age-decline in both measures. Men’s energetic status as indicated by body mass index was not associated with testosterone values or age-related decline. Conclusions Within socioecological contexts of smaller scale society, these data suggest that blunted age-decline in men’s testosterone levels is primarily due to population variation in parental investment rather than energetic constraint.
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Observations were made on 45 individually recognized adult female reindeer (Rangifer tarandus) as to exact date of parturition and antler shedding. Fifty percent of the cows had shed their antlers within 5 days postpartum. The maximum number of sheddings per day occurred on the sixth day after parturition. Postpartum retention of antlers varied from 1 to 11 days. No difference was found between old and young cows. The significance of antlers in female reindeer during calving season is discussed. It is supposed that possession of antlers gives the cow high social status which, combined with a high aggressive level, enables her to drive away other reindeer from the calving area, the calf thus being prevented from establishing contact with strange reindeer. It is supposed that the establishment of social mother-calf bonds would be impeded if strange reindeer were allowed to interfere.
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Dominance-subordination relationship in semi-domestic reindeer was studied in a group of 16 animals. They were enclosed and for identification they were marked with figures. Observations were made during three periods in autumn and winter of 1962-1963, and studies were also made in free-ranging reindeer. The purpose of the studies was to observe whether the rank order was changed with season, after the shedding of antlers and with other changes in the reindeer and in their environment. During the rutting season the mature bulls were at the top of the dominant list. Within each sex group, age seemed to be an important factor for the rank order, while size and strength were more important between the sex groups, During this time the mature cows were very aggressive to the young bulls. In winter time the reindeer exchanged their feeding craters after a pattern that corresponded to the dominance order in the herd. The mature cows were relatively high-ranked during this time and the calves shared the status of their mothers only when mother and calf were grazing in the same crater. The unantlered bulls were then rather low-ranked, while the bullock in the group remained on a high level in the ranking list. A test was made to discover the influence of antlers upon the hierarchy. Antlers were cut from some animals of the highest status and a drop in the hierarchy after this change was observed. The discontinuity in the ranking lists is discussed as well as some aspects of the biological significance of antlers in reindeer.
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p>1. The effect of exogenous testosterone on ander growth in yearling male reindeer (Rangifer tarandus tarandus) was tested. 2. Testosterone (33 mg/kg) inhibited antler growth, and in one animal induced cleaning and subsequent casting of the antlers. This animal grew a new set of antlers, which were cleaned at the normal time. 3. During treatment, there was an inverse relationship between peak testosterone levels and antler growth rate. 4. There was no effect of treatment on body weight or food intake. 5. It is concluded that the effects of testosterone on antler growth are qualitatively the same in reindeer as in other deer. However, because high testosterone doses were necessary to produce effects, it is questionable whether this hormone normally is responsible for the cessation of antler growth in reindeer. Virkningen av testosteron på gevirvekst hos ettårige reinbukker. Abstract in Norwegian / Sammendrag: 1. Virkningen av testosteron på gevirvekst hos ett-årige reinbukker (Rangifer tarandus tarandus) ble undersøkt. 2. Testosteron (33 mg/kg) hemmet gevirveksten, og hos ett dyr førte behandlingen til at geviret ble feiet og deretter felt. Deretter vokste det ut ett nytt gevir, som ble feiet til vanlig tid. 3. Det var en negativ korrelasjon mellom maksimale testosteronnivåer og gevirvekst under behandlingen. 4. Det var ingen effekt på forinntak eller vektutvikling. 5. Det blir konkludert med at virkningen av testosteron på gevirvekst er kvalitativt den samme hos rein som hos andre hjortedyr. Det er likevel tvilsomt om testosteron normalt er ansvarlig for avslutningen av gevirvekst hos rein, fordi store testosterondoser måtte til for å få noen virkning. Testosteronin vaikutus vuodenikåisten urosporojen sarvien kasvuun. Abstract in Finnish / Tiivistelmä: 1. Tutkimuksessa seurattiin ruiskeena annetun testosteronin vaikutusta vuodenikåisten urosporojen (Rangifer tarandus tarandus) sarvien kasvuun. 2. Testosteron! (33 mg/kg) hidasti sarvien kasvua, aiheuttaen yhdesså elåimesså sarvien kelomisen ja pudottamisen. Talle elåimelle kasvoi uudestaan sarvet, jotka se keloi normaaliin aikaan. 3. Testosteronin huipputaso veresså oli kåsittelyaikana kååntåen verrannollinen sarvien kasvunopeuteen. 4. Kåsittely ei vaikuttanut elåinten ruumiinpainoon eikå niiden ruokahaluun. 5. Voidaan pååtellå testosteronin vaikutuksien sarvien kasvuun olevan porossa laadullisesti yhtålåiset kuin muissakin hirvielåimisså. Koska vaikutuksen aikaansaamiseksi vaadittiin korkeita testosteroniannoksia, voidaan kuitenkin pitåå kyseenalaisena, onko kyseinen hormoni normaalisti vastuussa poronsarven kasvun keskeytymisestå.</p
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Data were obtained from post-mortem investigations of 190 culled and road-killed muntjac bucks between 1967 and 1989. Although adult bucks (i.e. those having undergone at least one antler cycle) have a synchronous annual antler cycle, unlike temperate-zone cervids there was little seasonal variation in testis size or activity, or in the size and activity of the epididymidis or accessory reproductive glands. Spermatogenesis was not abated when the antlers were in velvet and year-round fertility was achieved without additional sperm storage. There was little seasonal change in plasma testosterone concentrations in samples obtained from captive and free-living bucks although castration caused antler casting and prevented mineralization. Hence the data are equivocal as to the role of steroids in driving the antler cycle; experimental work on this species would be valuable in examining the mechanisms which regulate the antler cycle.
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The intraspecific combat behavior of male muntjacs is described. Their antlers are found to be an essential instrument allowing tusk blows to be delivered during serious fights. A knowledge of the fighting behavior of muntjacs improves our understanding of the evolution of the aggressive behavior of male cervids and therefore of the origin and evolution of antlers.
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The misnamed 'Irish Elk' is a late Pleistocene giant deer that ranged southward to North Africa and eastward to China. Since its first scientific description in 1697, it has played a major role in debates about the history of life. Cuvier used it to prove the fact of extinction and set the basis for a geologic time scale. Later, Megaloceros became the rallying point for anti-Darwinians; they invoked orthogenesis to deny natural selection and attributed extinction to an inadaptive trend towards immense antlers. The antlers posed a severe difficulty for the modern synthesis: they were generally explained as allometric correlates of advantageous increases in body size that offset the problems of admittedly disproportionate antlers. Virtually every textbook in evolution cites Megaloceros as a case of allometry contra orthogenesis: nonetheless, no one has ever generated any quantitative data about it. I measured 79 skulls and antlers of Megaloceros to resolve two questions bearing upon the allometric hypothesis: 1) Does Megaloceros, at its maximal body size among cervine deer, lie on the extrapolated line for positive allometry of antlers among smaller cervines? 2) Does the intraspecific variation among adult stags of Megaloceros yield relatively large antlers in stags of large body size? The answer to both questions is undoubtedly yes (Figs. 1-2, 7-10). 1) the static, interspecific allometry of adult cervines is strongly positive; Megaloceros has the predicted antler size for its body size (moose have relatively small antlers for their body size). 2) The exponent of intraspecific allometry is about 2.5. If selection acted to preserve deer of large body size, relatively large antlers would follow as a consequence of correlation. Yet the fact of positive allometry need not provoke the usual interpretation: large bodies might be a consequence of advantageous antlers, or both antlers and bodies might be selected in concert. The assumption of disproportionate antlers is based on the a priori notion that antlers must function as weapons in battle: 90 pound antlers, mounted with tines pointing backward on a 5 pound skull cannot be regarded as well-designed for such a purpose. But deer often use their antlers to establish dominance and win access to females by display and ritualized combat. Moreover, display is especially important in large deer and deer with palmated antlers. The antler morphology of Megaloceros is ideally suited for display: smaller deer must rotate their heads to show the palm. The torque produced by rotation in Megaloceros would have posed severe mechanical problems. But, alone among deer with palmated antlers, Megaloceros displayed its full palm when simply looking straight ahead. The immense antlers of Megaloceros were advantageous in themselves. Its extinction may be traced to late glacial changes in climate.
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Megaloceros giganteus, the famous Eurasian giant deer of Late Pleistocene times, possessed the largest antlers ever known: reliable estimates of their total span range up to 4 m.
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Hornlike organs evolved independently in a number of mammalian families. Though these organs assumed great diversity they did evolve into several general functional types. A short review of the structure and development of hornlike organs is given. Some views on horn function and evolution are critically discussed. The evolution of hornlike organs is visualised as follows: In primitive large mammals the head blow became effective as a fighting form due to increased mass and inertia of the heads. Some forms grasped this potential. Combats were carried out from the broadside while opponents delivered head blows on each others body. Skull protuberances now became adaptive. Concurrently, defensive mechanisms evolve, decreasing the effectiveness of these protuberances. Foremost among them is a thick, heavy hide or specialised dermal shield. These adaptive syndromes gave no impetus towards larger and more complex horns. This impetus arose with the appearance of a new method of defense - catching the opponent's blows with the horned head. This leads to the evolution of heavy skulls and horns capable of catching and holding the opponent's head. The target area of attack remained the body. Frontal engagements resulted from the opponents' attempts to control each others horned head. It is shown that bovids and suids followed similar evolutionary roads in their mode of combat. The tusks of the suidae fulfill the same function and were subject to similar selection as the horns of short horned bovids. Thus Sus and Oreaisinos, and Bos and Phacochoerus are entirely similar in their mode of combat, hornlike organs and defense mechanisms. The primitive frontal engagement gave rise to two different modes of combat, ramming and wrestling. The
Article
Reviews evidence for 5 functional explanations of the evolution of antlers in male cervids. 1) There is extensive evidence that antlers are used in fights between competing males. Fights are regular during the breeding season and can be damaging. Antlers have proved to be effective weapons of defence and offense, and there is no systematic evidence to support the suggestion that antler-less males (hummels) are more successful in competition for females than antlered stags. 2) Though male deer sometimes use their antlers in defence against predators, the absence of antlers in females of most species suggests that this is not their principal function. 3) Nor does it seem likely that antlers evolved as heat-regulating mechanisms. 4) There is no conclusive evidence that males assess each other by their relative antler size, most measures of antler size and shape are not closely correlated with dominance or fighting ability. 5) Nor is there firm evidence that females selectively mate with large-antlered males. Antlers thus evolved as weapons and are retained by selection because of their function in intra-specific combat. -from Author
Article
Synopsis The mechanism involved in the control of antler growth was studied in three experiments using red deer living at Reedie Hill Deer Farm in Fife. Scotland. Observations were made on three congenitally polled stags (hummels) captured from the wild, one female red deer (hind) induced to grow antlers by treatment with testosterone, and four castrated stags (havicrs). The overall results support the view that in the stag it is the increase in secretion of testosterone by the testes at puberty which stimulates the initial development of the antler pedicles, and it is the subsequent seasonal cycle in the secretion of testosterone which dictates the seasonal casting and regeneration of the antlers. The high blood levels of testosterone in the autumn cause the calcification and death of the antler tissue, and also prevent the process of rejection of this tissue for the remainder of the breeding season. The dead antlers can thus act as an insensitive fighting weapon when rival stags compete for access to females during the rut. When the testes become fully regressed in spring, it is the withdrawal of testosterone which allows the old antlers to be cast off. and the wound on the surface of the antler pedicles triggers the regeneration of new antlers. In hummel stags which have failed to complete the initial growth of the antler pedicles, it is possible to trigger the development of antler tissue by wounding the rudimentary pedicle, and once this tisue has formed it is cast and regrown annually due to the seasonal evele in the activity of the testes.
Article
The behaviour of red deer stags following antler casting, antler breakage, antler amputation and antler stunting was studied to establish the ways in which antlers normally function. It was found that after the loss of antlers, either naturally or artificially, individuals became less effective in competition with other stags, resulting in loss of social rank in the bachelor group and failure to secure hinds in the rut. The observations indicate that antlers normally function as a weapon and guard in conflict between stags and allow animals to lock their heads together for fighting. Of equal importance is the visual effect of the antlers denoting status of the individual, allowing for domination without physical force. While the stags are living in the bachelor herds the antlers appear to be the principal status symbol. During the rutting season, additional display symbols and characteristics come into use, and it is the significance of these in intimidation which allows stags without antlers (hummels) to be successful in the rut. There is slight evidence to support the idea that the antlers function in attracting hinds.
Article
In order to study the seasonal reproductive changes in the Red deer stag (Cervus elaphus L.), two adult animals were shot per month in 1968. During May and June the stags were in a state of reproductive quiescence, and the antlers were rapidly growing in velvet. Testosterone was barely detectable in testicular tissue, and the seminiferous tubules were regressed with small numbers of spermatogonia and primary spermatocytes but no spermatids or spermatozoa. The accessory organs were also fully regressed, the concentrations of fructose in the seminal vesicles and ampullae were minimal, and the epididymides were devoid of spermatozoa. At the end of June, there was a slight increase in the testicular testosterone concentration, coincident with an increase in the number of spermatogonia in the seminiferous tubules. In July, as the testosterone continued to increase, spermatids appeared and the tubules began to enlarge. Histological changes were seen in the epithelia of the epididymides, ampullae, prostate and seminal vesicles, although organ weights and vesicular fructose concentration remained unchanged. In August, there was a marked increase in testicular testosterone, spermatogenesis was now complete and the tubules reached their maximum diameter. The accessory organs had increased in weight considerably, and the vesicular fructose concentrations were also elevated. The antlers were transformed from velvet to hard horn, and the neck girth had started to expand. The stags showed rutting behaviour from mid-September to the end of October, when their testicular testosterone concentrations were 1000 times the resting level. All the accessory organs reached their maximal stage of development and the fructose concentrations were highest. The neck girth was maximal, the voice changed to a deep-throated roar, and the urine developed a characteristic rutting odour. By November, when rutting activity had almost ceased, the testicular testosterone concentrations had declined, the seminiferous tubules had shrunk, and spermatogenesis was much reduced. The accessory organs had also regressed. During the winter and spring, androgenic and spermatogenic activity of the testis became progressively more reduced, while the epididymis remained packed with spermatozoa. In April, the testicular testosterone concentration reached very low levels, spermatogenesis degenerated still further with no division stages maturing beyond primary spermatocytes; the accessory organs became completely involuted, and the antlers were cast. Even during the period of reproductive quiescence, it is probable that the testis was still secreting some testosterone; the castrated stags grew abnormal antlers, and their accessory organs were more involuted than those of any of the intact stags. This annual cycle of reproductive activity in the stag was considered to be controlled principally by daylight length, and was associated with changes in the pituitary gland, the adrenal, and the thyroid. There were also pronounced changes in body weight which were a direct consequence of rutting behaviour.
Article
For 10 months of the year red deer stags live together in social groups. These groups then break up, and the animals exhibit a complex pattern of sexual behavior during a short rutting season in September and October. We have utilized this clear separation between social and sexual behavior to try and establish experimentally in free-ranging wild animals the way in which testosterone influences the two types of activity.It was found that castration of adult stags at any season of the year abolished all subsequent rutting behavior. The animals also became less aggressive within the bachelor groups and thus dropped in social status. When castrates were implanted with testosterone in December they developed all aspects of rutting behavior within a few weeks and showed conspicuous aggressiveness to other stags, and regained their dominance on returning to the bachelor group. When castrates were given implants of testosterone in April and June, no immediate rutting response was elicited, although increased social aggressiveness was again apparent; but subsequently these animals developed rutting behavior in the autumn at the normal rutting time. Testosterone implants in intact stags at any season failed to induce a second rut, but the animals did show striking changes in aggression.The results are complicated by the fact that the antler cycle of the stag is controlled by the level of testosterone, and, therefore, many of the experiments have led to changes in the antlers which have themselves affected behavior. Direct effects of testosterone on behavior can only be inferred when the hormone treatment is unaccompanied by changes in the antlers.The general conclusion is that testosterone plays largely a permissive role in the control of rutting behavior; the presence of the hormone is essential, but other factors act as an overriding control, and determine the time of year at which rutting behavior is expressed. In contrast, testosterone has a direct inductive effect on social aggressive behavior, which can be induced at any season of the year.
Article
SEVERAL of us at the Harvard Medical School have been interested for some years in the study of the antlers of deer. We have attempted more especially to analyze by experimental means the factors controlling the annual renewal, growth, and shedding of the antlers. For this purpose, we have availed ourselves of a group of Virginia or white-tailed deer kept in captivity at the Wildlife Research Center, Delmar, N. Y. The present investigations have been concerned with the effects of castration upon the growth of the antlers of deer at different ages and times of the year, as well as with the effects of testosterone propionate administered to both normal and castrated male and female deer.
Article
The Deer and the Tiger is Schaller's detailed account of the ecology and behavior of Bengal tigers and four species of the hoofed mammals on which they prey, based on his observations in India's Kanha National Park. "This book is a treasure house of biological information and it is also a delight to read. . . . Excellent phoographs accompany the text."—Robert K. Enders, American Scientist "The one book that has been my greatest source of inspiration is The Deer and the Tiger by George Schaller, based on the first ever scientific field study of the tiger. . . . This book is written by a scientist, but speaks from the heart. . . . It reveals startling information on feeding habitats, territorial behaviour, and the nuances that make up the language of the forest; you become totally immersed in the world of the tiger. . . . For all of us who work in tiger conservation, this book is the bible."—Valmik Thapar, BBC Wildlife
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The tendency for large deer species to have relatively big antlers for their body size has been explained as the result of an inevitable evolutionary trend leading to increased antler size1-4, of linkage between genetic factors influencing body size and relative antler size5, of the increased need for larger deer to lose heat6 and of an increased reliance of larger deer species on displays to avoid fighting7. Here we test an alternative hypothesis: that large deer species tend to be more polygynous than smaller ones and that intense inter-male competition in large species has led to the development of relatively large antlers. Analysis of comparative data8-42 confirms two predictions based on this hypothesis: (1) that large deer species form bigger breeding groups than small ones; and (2) that deer which form large breeding groups have relatively larger antlers for their body size than those that form smaller ones. However, antler size is not proportional to body size among species that form breeding groups of similar size, indicating that other factors must also be involved.
Article
Antler and testicular cycles were studied in a group of free ranging axis deer stags kept out of doors in southern England. Within the herd, there was little evidence of a clear seasonal synchrony in the antler cycle. Detailed information obtained from 4 stags indicated that there was a fixed relationship between stage of the antler cycle and testis diameter; minimum testis diameter occurred 1-2 months after antler casting whereas maximum testis diameter occurred when stags were in hard antler. Changes in body weight, circumference of the neck and plasma testosterone concentrations largely paralleled those of testis diameter. Motile spermatozoa were collected at all stages of the testis cycle. Six animals in the early stages of antler growth were selected from the herd in May and 3 of these were implanted with 1 g melatonin in a Silastic rubber envelope. Each animal was captured on 3 subsequent occasions at monthly intervals. Melatonin was without effect on the rate of increase in size of the testis, circumference of the neck or growth and cleaning of the antlers although 1 of the treated animals failed to cast his antlers at the expected time 8 months after cleaning. We conclude from this study that there is little or no seasonal photoperiodic entrainment of the antler and testicular cycles of males in this population of axis deer.
Article
HENSHAW1 has accepted Coope's premise2 that giraffes have retained the skin-covered horn-like structures of the palaeomerycids, from which they are descended, because there have been no significant changes in the climate-the hypothesis being that the formation of antlers is a response to environmental temperatures. But the nature of the giraffe horn can be seen in relation to the form of the animal and its social requirements, without any reference to the cervid antler3. As Henshaw states, the horn-like structures of the giraffe are analogous to the summer antlers of deer, in that they have points of resemblance, but there is no justification for invoking climate as an explanation of their form. They are specialized structures in the giraffe Giraffa camelopardalis L. of which the skin covering is no more velvet-like than that covering the rest of the animal's body, and it is certainly not vascular like the velvet skin of antler buds.
Article
``IF stags be mutilated,'' wrote Aristotle1, ``when, by reason of their age, they have as yet no horns, they never grow horns at all; if they be mutilated when they have horns, the horns remain unchanged in size, and the animal does not lose them.'' What Aristotle already knew, other biologists confirmed centuries later2, and today we know that if an adult deer is castrated in the autumn or winter after the velvet has been shed, its bony antlers are lost within several weeks and replaced by new ones that are retained permanently in velvet. Such ``castrate antlers'' will continue to undergo annual increments of growth, and may eventually develop into very grotesque headpieces, or ``perukes''. Only by administering testosterone or oestrogen can the velvet be induced to peel off and the antlers shed3.
The significance of antlers in the social life of the Cervidae
  • Bubenik A. B.
The evolutionary origin of antlers
  • Coope G. R.
A theory for the occurrence of antlers in females of the genus Rangifer
  • Henshaw J.
  • Millais
Ovariectomy in October causes premature antler casting in female reindeer
  • Tyler N. J. C.
  • Millais J. G.