Male-female Pairs Research Articles

The lack of female dominance in golden‐brown mouse lemurs suggests alternative routes in lemur social evolution

Female dominance is a well-known trait of lemurs, although it has not been reported from all species and is still often unexplored, especially in the nocturnal species. We examined the intersexual dominance relationships in Microcebus ravelobensis, a congener of M. murinus who is well known for its female dominance. Given the many similarities in biology, it was predicted that M. ravelobensis should also possess female dominance. Seventeen unfamiliar male-female pairs were formed with animals captured in northwestern Madagascar and kept in a two-cage setting (one cage for each animal) for up to 1 week. Four encounter experiments were conducted with each pair. In contrast to the expectations, females were not consistently dominant over their male partners. Only 3 of 17 dyads developed a clear agonistic asymmetry, among which were two cases of male dominance and only one case of female dominance. Because body mass differences did not explain the findings, various other possible explanations are discussed. It is suggested that food may not be the driving factor of female dominance in mouse lemurs. Instead, it is hypothesized that species-specific differences in the quality of sleeping sites (i.e., tree holes) and in social grouping patterns may better explain why some mouse lemur species have female dominance, whereas others like the golden-brown mouse lemur do not. It is concluded thatthese arguments and hypotheses may even hold true for other solitary foragers and may thereby lead to a better understanding of the variable social evolution in lemurs and primates in general.

Color-assortative mating in a color-polymorphic lacertid lizard

Color polymorphisms are common in lizards, which provide an excellent model system to study their evolution and adaptive function. The lacertid genus Podarcis is particularly interesting because it comprises several polymorphic species. Previous studies with lacertid lizards have tried to explain the maintenance of color polymorphisms by correlational selection between color morphs and several phenotypic traits. Particular attention has been paid to their putative role as signals reflecting alternative reproductive strategies under frequency-dependent selection, but the relationship between mating patterns and color polymorphism has not been previously considered. In this study, we use longitudinal behavioral data obtained during six consecutive breeding seasons (2006-2011) in a free-ranging polymorphic population of Podarcis muralis lizards to examine the hypothesis that lizards mate assortatively by color. We provide spectrophotometric data that confirm the existence of discrete color morphs and show that morphs are ontogenetically stable once they develop fully in sexually mature individuals. We also present data on the year-to-year variation of relative morph frequencies. Finally, we provide evidence that, over a 6-year period, homomorphic male-female pairs in the wild were significantly more common than heteromorphic pairs. Taken together, our results suggest that color assortative mating may be involved in the maintenance of discrete color morphs in this and other lacertid species. © 2012 The Author.

Social housing and alcohol drinking in male-female pairs of prairie voles (Microtus ochrogaster)

Social environment influences alcohol consumption in humans; however, animal models have only begun to address biological underpinnings of these effects. We investigated whether social influences on alcohol drinking in the prairie vole are specific to the sex of the social partner. In Experiment 1, control, sham, and gonadectomized voles were placed either in mesh-divided housing with a same-sex sibling or isolation with access to ethanol. In Experiment 2, animals were given an elevated plus maze test (EPM) and then females were paired with a castrated male followed by isolation or mesh-divided housing with access to ethanol. In Experiment 3, subjects categorized as low or high drinkers based on initial ethanol intake were placed in mesh-divided housing with an opposite-sex partner of the same or opposite drinking group and ethanol access. Subjects were then moved back to isolation for a final ethanol access period. Same-sex pairs showed social facilitation of drinking similar to previous reports. Gonadectomy did not affect alcohol drinking. Opposite-sex paired animals in Experiment 2 did not differ in alcohol drinking based on social housing. EPM measures suggested a relationship between anxiety-like behaviors and drinking that depended on social environment. Experiment 3 identified moderate changes in alcohol preference based on social housing, but these effects were influenced by the animal's own drinking behavior and were independent of their partner's drinking. Social influences on alcohol self-administration in prairie voles differ based on the sex of a social partner, consistent with human drinking behavior.

Host‐specific reproductive benefits, host selection behavior and host use pattern of the pinnotherid crab Calyptraeotheres garthi

In organisms using a wide variety of refuges, both the cost and benefits to the users might be refuge-specific. Under these circumstances, users using mechanisms (e.g., behavioral preference) that allow them to find and colonize refuges in which net benefits are maximized are expected to be selected by the environment. Herein, we tested the hypothesis that resource generalists display strong preferences for resources that provide the greatest reproductive benefits using Calyptraeotheres garthi, a crab that inhabits the limpets Crepidula cachimilla and Bostrycapulus odites in the south-western Atlantic. In the field, female crabs inhabiting C. cachimilla featured larger average body size, and subsequently, larger average fecundity and brood weight than those inhabiting B. odites. Thus, C. cachimilla is a higher quality host for C. garthi compared to B. odites. In contrast to expectations, host selection experiments revealed that female crabs were attracted to the host species from which they were collected and not to the host species that provided the greatest reproductive benefits (C. cachimilla). Host chemical and/or visual cues imprinted in crabs early during ontogeny (soon after colonization of their first host), rather than genetic differences, may explain the source-host fidelity of C. garthi. In the two hosts, females of C. garthi lead a solitary lifestyle and appear to inhabit the same host individual for long periods of time as indicated by the close relationship between female crab and host body size. The frequency of male–female pairs within host individuals was lower than expected by chance alone. Also, males were, on average, smaller than females and did not appear to inhabit the same host individual for long periods of time. The above suggests that males might be using a pure‐search mating strategy, continuously roaming among host individuals in search of receptive females. The details of the mating system of C. garthi need to be further investigated.

Chronic systemic administration of serotonergic ligands flibanserin and 8-OH-DPAT enhance HPA axis responses to restraint in female marmosets

Flibanserin, a novel serotonin (5-HT)(1A) agonist and 5-HT(2A) antagonist, has been shown to increase sexual desire and reduce distress in women with Hypoactive Sexual Desire Disorder (HSDD). In marmoset monkeys, flibanserin has demonstrated pro-social effects on male-female pairmates, while the classic 5-HT(1A) agonist 8-OH-DPAT suppresses female sexual behavior and increases aggressive interactions between pairmates. Activation of 5-HT(1A) and 5-HT(2A) receptors is known to stimulate the hypothalamic-pituitary-adrenal (HPA) axis. This study aims to characterize the effects of repeated flibanserin and 8-OH-DPAT administration on the marmoset HPA axis and to elucidate endocrine correlates of altered marmoset pair behavior. Adrenocorticotropic hormone (ACTH) and cortisol were examined at baseline and during 5-HT(1A) agonist and restraint challenges in 8 female marmoset monkeys receiving daily flibanserin (15mg/kg) and an additional 8 female marmosets receiving 8-OH-DPAT (0.1mg/kg) for 15-16weeks. Corresponding vehicle treatments were administered in a counterbalanced, within-subject design. All females were housed in stable male-female pairs. Treatment-induced changes in ACTH and cortisol levels were correlated with previously assessed marmoset pair behavior. While morning basal cortisol levels and HPA responses to a 5-HT(1A) agonist challenge were not altered by chronic flibanserin or 8-OH-DPAT, both treatments increased the responsiveness of the marmoset HPA axis to restraint. Enhanced ACTH responses to restraint correlated with reduced sexual receptivity and increased aggression in 8-OH-DPAT-, but not in flibanserin-treated female marmosets. Unaltered HPA responses to a 5-HT(1A) agonist challenge after chronic flibanserin and 8-OH-DPAT treatments indicate little or no de-sensitization of the HPA axis to repeated 5-HT(1A) manipulation. Chronic 8-OH-DPAT, but not flibanserin, leads to aggravated ACTH responses to stress that may contribute to anti-sexual and anti-social behavior between 8-OH-DPAT-treated females and their male pairmates. Despite similar flibanserin and 8-OH-DPAT induced ACTH responses to restraint stress, flibanserin-treated females show unchanged cortisol profiles. This is possibly due to flibanserin's regional selectivity in 5-HT(1A) activation and concurrent 5-HT(2A) inhibition. The contrasting restraint-related cortisol responses emulate contrasting behavioral phenotypes of diminished pair-bond of 8-OH-DPAT-treated females compared to the more affiliative pair-bond of flibanserin-treated females.

Impact of negative frequency-dependent selection on mating pattern and genetic structure: a comparative analysis of the S-locus and nuclear SSR loci in Prunus lannesiana var. speciosa

Mating processes of local demes and spatial genetic structure of island populations at the self-incompatibility (S-) locus under negative frequency-dependent selection (NFDS) were evaluated in Prunus lannesiana var. speciosa in comparison with nuclear simple sequence repeat (SSR) loci that seemed to be evolutionarily neutral. Our observations of local mating patterns indicated that male-female pair fecundity was influenced by not only self-incompatibility, but also various factors, such as kinship, pollen production and flowering synchrony. In spite of the mating bias caused by these factors, the NFDS effect on changes in allele frequencies from potential mates to mating pollen was detected at the S-locus but not at the SSR loci, although the changes from adult to juvenile cohorts were not apparent at any loci. Genetic differentiation and isolation-by-distance over various spatial scales were smaller at the S-locus than at the SSR loci, as expected under the NFDS. Allele-sharing distributions among the populations also had a unimodal pattern at the S-locus, indicating the NFDS effect except for alleles unique to individual populations probably due to isolation among islands, although this pattern was not exhibited by the SSR loci. Our results suggest that the NFDS at the S-locus has an impact on both the mating patterns and the genetic structure in the P. lannesiana populations studied.

Demography of Simakobu (Simias concolor) and the Impact of Human Disturbance

Asian colobines typically live in small one-male groups (OMGs) averaging five adult females, but Simias concolor (simakobu or pig-tailed langur) is considered an exception because mostly adult male-female pairs have been reported. However, based on their phylogenetic position and marked sexual dimorphism, simakobu are also expected to form OMGs with multiple females. The preponderance of small groups could be the result of human disturbance (hunting or habitat disturbance) reducing group size in the recent past. To investigate this possibility, we documented the demography of ten wild simakobu groups from January 2007 until December 2008 at an undisturbed site, the Peleonan Forest, Siberut Island, Indonesia. We assessed the population-specific size and composition of groups and documented demographic changes due to births, disappearances, and dispersals throughout our 2-year study. We found OMGs with 3.0 adult females on average in addition to all-male groups, but no adult male-female pairs. The ratio of 0.5 infants per adult female (and 0.64 births per female-year in focal groups) suggested that birth rates were similar to those of other Asian colobines. In 5.1 group-years, we observed six dispersal events and six temporary presences (i.e., less than 3 months' residency). Both males and females dispersed, and juveniles seemed to disperse more frequently than adults. To assess the impact of human disturbance on simakobu demography, we compiled data for seven additional populations from the literature and compared them using multiple regressions. Adult sex ratio and the number of immatures per group were influenced negatively by hunting and positively by habitat disturbance while reproductive rates were not significantly affected by either variable. These findings suggest that adult male-female pairs may result from hunting pressure reducing group size, and that conservation action to reduce hunting in the Mentawai Islands is needed to ensure the survival of this critically endangered species.

Tail length and sexual selection in a monogamous, monomorphic species, the Roseate Tern Sterna dougallii

Both male and female Roseate Terns (Sterna dougallii) have unusually long outer tail feathers, and males tend to have longer tails than females. We examined whether these tail streamers may have evolved as a result of sexual selection, using data from a 15-year study at Bird Island, Massachusetts, USA. Data on tail length were analyzed for 2,515 terns, of which 745 were of known sex. Tail length was positively correlated with predictors of reproductive success, such as laying date, body mass, and age, and thus can act as an indicator of mate quality. The increase in mean tail length with age appeared to result from a combination of growth in relatively young terns and differential survival among older terns. The mean duration of pair bonds was short at 1.73 years. A female-biased sex ratio is present in this population, and we demonstrated that short-tailed females are not preferred mates: females paired to males had longer tails than those in female–female pairs or other multi-female associations. In male–female pairs, tail lengths of mates were correlated, but this may have resulted in part from the correlation in ages. These observations are consistent with the hypothesis that tail streamers are used by both sexes in mate choice. In contrast to our results for tail length, tail symmetry was not significantly related to indices of individual quality and was not significantly correlated between mates.

Social tolerance in a despotic primate: co-feeding between consortship partners in rhesus macaques.

Food sharing among nonkin-one of the most fascinating cooperative behaviors in humans-is not widespread in nonhuman primates. Over the past few years, a large body of work has investigated the contexts in which primates cooperate and share food with unrelated individuals. This work has successfully demonstrated that species-specific differences in temperament constrain the extent to which food sharing emerges in experimental situations, with despotic species being less likely to share food than tolerant ones. However, little experimental work has examined the contexts that promote food sharing and cooperation within a species. Here, we examine whether one salient reproductive context-the consortship dyad-can allow the necessary social tolerance for co-feeding to emerge in an extremely despotic species, the rhesus macaque (Macaca mulatta). We gave naturally formed male-female rhesus macaque pairs access to a monopolizable food site in the free-ranging population at Cayo Santiago, Puerto Rico. Using this method, we were able to show that tolerated co-feeding between unrelated adults can take place in this despotic species. Specifically, our results show that consort pairs co-fed at the experimental food site more than nonconsort control pairs, leading females to obtain more food in this context. These results suggest that co-feeding is possible even in the most despotic of primate species, but perhaps only in contexts that specifically promote the necessary social tolerance. Researchers might profit from exploring whether other kinds of within-species contexts could also generate cooperative behaviors.

Determinants of Pair-Living in Red-Tailed Sportive Lemurs (Lepilemur ruficaudatus).

Pair-living and a monogamous mating strategy are rare and theoretically unexpected among mammals. Nevertheless, about 10% of primate species exhibit such a social system, which is difficult to explain in the absence of paternal care. In this study, we investigated the two major hypotheses proposed to explain the evolution of monogamy in mammals, the female defence hypothesis (FDH) and the resource defence hypothesis (RDH), in red-tailed sportive lemurs (Lepilemur ruficaudatus), a nocturnal primate from Madagascar. We analysed behavioural data from eight male–female pairs collected during a 24-mo field study to illuminate the determinants of pair-living in this species. Male and female L. ruficaudatus were found to live in dispersed pairs, which are characterised by low cohesion and low encounter rates within a common home range. Social interactions between pair partners were mainly agonistic and characterised by a complete absence of affiliative interactions – body contact was only observed during mating. During the short annual mating season, males exhibited elevated levels of aggression towards mates, as well as extensive mate guarding and increased locomotor activity. In addition, males were exclusively responsible for the maintenance of proximity between pair partners during this period, and they defended their territories against neighbouring males but not against females. Together, these results point towards the importance of female defence in explaining pair-living in L. ruficaudatus. We discuss the spatial and temporal distribution of receptive females in relation to the female defence strategies of males and suggest possible costs that prevent male red-tailed sportive lemurs from defending more than one female.

The dynamics of reproductive rate, offspring survivorship and growth in the lined seahorse, Hippocampus erectus Perry, 1810

SummarySeahorses are the vertebrate group with the embryonic development occurring within a special pouch in males. To understand the reproductive efficiency of the lined seahorse, Hippocampus erectus Perry, 1810 under controlled breeding experiments, we investigated the dynamics of reproductive rate, offspring survivorship and growth over births by the same male seahorses. The mean brood size of the 1-year old pairs in the 1st birth was 85.4±56.9 per brood, which was significantly smaller than that in the 6th birth (465.9±136.4 per brood) (P<0.001). The offspring survivorship and growth rate increased with the births. The fecundity was positively correlated with the length of brood pouches of males and trunk of females. The fecundity of 1-year old male and 2-year old female pairs was significantly higher than that from 1-year old couples (P<0.001). The brood size (552.7±150.4) of the males who mated with females that were isolated for the gamete-preparation, was larger than those (467.8±141.2) from the long-term pairs (P<0.05). Moreover, the offspring from the isolated females had higher survival and growth rates. Our results showed that the potential reproductive rate of seahorses H. erectus increased with the brood pouch development.

Measuring Empathizing and Systemizing with a Large US Sample

A large number of people completed one of two versions of the empathizing quotient (EQ) and systemizing quotient (SQ). One version had the negatively phrased items all re-worded. These re-worded items were answered more rapidly than the original items, and for the SQ produced a more reliable scale. Subjects gave self-assessments of empathizing and systemizing, and these were moderately correlated, r≈.6, with their respective quotients. Females had on average higher empathizing scores and males had on average higher systemizing scores. If a female-male pair was chosen at random, the female would have the higher empathizing score about two-thirds of the time, and the males would have the higher systemizing score about two-thirds of the time.

The reproductive cycle of the Tasmanian devil (Sarcophilus harrisii) and factors associated with reproductive success in captivity

Numbers of wild Tasmanian devils are declining as a result of the fatal, transmissible Devil Facial Tumor Disease. A captive insurance population program has been initiated but current captive breeding rates are sub-optimal and therefore the goal of this project was to increase our understanding of the estrous cycle of the devil and elucidate potential causes of failed male–female pairings. Temporal patterns of fecal progestagen and corticosterone metabolite concentrations were examined for females (n=41) in three categories of reproductive status (successful: viable young, n=20 estrous cycles; unsuccessful: paired with a male but no young confirmed, n=44 estrous cycles; non-mated: no access to a male during estrus, n=8 estrous cycles) but substantial differences were not found. Females were more likely to produce pouch young if pairing with the male extended into late proestrus (P<0.05), thereby decreasing the time between pairing and presumed ovulation. The interval between the end of proestrous elevation in progestagen metabolite concentrations and the beginning of the luteal phase was 7.6±2.3days in successful females. The length of the luteal phase in successful females was 12.5±1.4days which was not different from unsuccessful or non-mated females (P>0.05). Unsuccessful females had 1–3 estrous cycles within a single year. Successful females were predominantly wild-caught (17/19, 90%) and most produced young following the first estrous cycle of the season (18/20, 90%). Unsuccessful females were predominantly captive born (20/27, 74%) in this study. It is possible that a proportion of females that do not produce pouch young achieve conception but the timing of reproductive failure continues to be elusive in this species.

Extreme habitat specialisation and population structure of two gorgonian-associated pygmy seahorses

Pygmy seahorses are a group of little-known miniature hippocampid fish that differ considerably in biology and ecology from their larger congeners. We estimated the population density, sex ratio and habitat of 2 sympatric, obligate gorgonian-associated pygmy seahorses, Hippocampus bargibanti and H. denise, in a 20 km long coastal marine protected area in southeast Sulawesi, Indonesia. Belt transects covering 200 m(2) each were surveyed at 7 sites and 5 depth contours to record the density of seahorses and their host gorgonians. The population density (+/- SE) was 1.17 (+/- 0.27) per 200 m(2) for H. denise and 0.34 (+/- 0.20) per 200 m(2) for H. bargibanti, some of the lowest densities for unexploited seahorse populations studied thus far. Male-female pairs (43.9%) were the most common group composition for H. denise, with single, 3 or 4 individuals found on 19.5, 7.3 and 29.3% of inhabited gorgonians, respectively. H. denise inhabited 7.8% of Annella reticulata gorgonians within the survey area but were recorded from a total of 8 gorgonian genera during extensive opportunistic ad hoc searches. Annella spp. density was 10.7 times higher than that of Muricella spp. (the sole host of H. bargibanti), of which 20.0% were inhabited. The small population size, occurrence of pygmy seahorses in groups on their hosts with the resulting skew in sex ratios, and habitat specialisation likely all impact the species' population dynamics, and hence these need to be considered in conservation management strategies.

Spinning behaviour and morphology of the spinning glands in male and female Aposthonia ceylonica (Enderlein, 1912) (Embioptera: Oligotomidae)

Embioptera (webspinners) are unique among insects in that juvenile and adults of both sexes spin silk. They possess spinning apparatuses in the basitarsomeres of their prothoracic legs, which they use to build galleries as habitat and protection. Embioptera are primitively social and cooperate in building the galleries. They also show sexual dimorphism that comprises modifications of the mandibles in males, the winglessness of the females and differences in the morphology of the forelegs. In the present investigation we address the correlation of spinning behaviour and sexual dimorphism in the spinning apparatus of Aposthonia ceylonica (Enderlein, 1912). To analyse spinning behaviour we conducted video observations of Ap. ceylonica in artificial habitats. We observed females and males alone as well as female–male pairs to cover possible effects of interactions between sexes. The morphology of the spinning apparatus was analysed and reconstructed using high resolution X-ray computed tomography (SRμCT). The observations show that during trials of 24h adult males and females produce similar amounts of silk per body weight, despite the fact that adult males do not feed, perhaps due to modifications of their mandibles related to courtship that interfere with feeding. Spinning glands in males are distinctly smaller than in females in absolute values, which reflect the general size difference in females and males. Despite their smaller body size, the volumes of reservoirs of spinning glands are larger in males in relative as well as in absolute values. Together with spinning behaviour and the amount of silk production, this indicates that males produce and store gland secretions in the large reservoirs prior to their final moult for later use.

江西鄱阳湖流域中华秋沙鸭越冬期间的集群特征

2010年11月-2011年3月,采用样线法对江西鄱阳湖流域8个河段的中华秋沙鸭<em>Mergus squamatus</em>的集群特征进行了研究。中华秋沙鸭的集群类型包括雄性群、雌性群、混合群、雌性孤鸭和雄性孤鸭5种类型。越冬期间共记录到89群次,432只次中华秋沙鸭。其中,混合群是最多的一种集群方式,孤鸭也是越冬期间出现频次较高的一种特殊的集群方式。集群类型存在时间变化(<em>P</em><0.01)。混合群中,大多数群体中雌性个体数多于雄性个体或者是一雌一雄。89群次中,孤鸭和2-8只群占总群数的87.64%,提示中华秋沙鸭主要以集小群分散活动。中华秋沙鸭越冬期间的群体大小是(4.85±4.97)只/群。不同集群类型的群体大小差异较大。集群大小可能与采砂、捕鱼、食物的丰富度等环境因子有关。调查结果显示,中华秋沙鸭越冬期间的性比是1:0.74(<em>n</em>=432)。中华秋沙鸭群体大小与性比有一定的关系。

Behavioral and Hormonal Consequences of Transporting Giant Pandas From China to the United States

Zoological institutions strive to ensure the welfare of nonhuman animals in captivity. Part of this effort involves reducing the level of distress experienced by an animal to the greatest extent possible. However, some necessary zoo management practices such as transportation induce stress responses. An extensive literature exists concerning the animal welfare implications of road transportation for farm and laboratory animals. There has, however, been little focus on the effects of air transportation on wild animals in captivity. Because many endangered species are transported by air for breeding purposes, it is especially important to study the effects of stress on these species. This study investigated the behavioral and hormonal consequences of transporting 4 giant pandas (2 male–female pairs) by air from China to the United States. An autoregressive test revealed that urinary cortisol measures were highest for 2 subjects, Lun Lun and Tian Tian, during the flight than during the remainder of the 30-day period posttransport (p < .01). No long-term behavioral changes or problems emerged as a result of the transport. The study found that more research is needed to develop a complete understanding of transportation stress and welfare in captive wildlife.

Morphometric Sexing of Northwest Atlantic Roseate Terns

Abstract.— A difficulty in the study of monomorphic species is the inability of observers to visually distinguish females from males. Based on a sample of 745 known-sex birds nesting at Bird Island, MA, USA, a discriminant function analysis (DFA) was used to sex Roseate Terns (Sterna dougallii) of the Northwest Atlantic population using morphological measurements. DFA using only the total length of the head (including the bill) correctly identified the sex of approximately 86% of the terns, which increased to 88% if both members of a pair were measured. Including additional measurements increased these percentages slightly, to 87% and 90%, respectively. These levels of accuracy are generally higher than those reported for other species of terns. Because female-female pairs are frequent in this population, one cannot assume that the member of a pair with the larger head is a male, and additional discriminant functions were developed to help separate female-female from male-female pairs.

Male mate choice by chemical cues leads to higher reproductive success in a bark beetle

Darwin’s sexual selection theory predicts that males should compete to gain access to females, while females should choose the best possible male. However, males can also be choosy, especially in monogamous mating systems with female-biased sex ratios and biparental care. A few studies show that in systems in which males are highly selective, chemical cues can lead to mating of individuals with high reproductive success. Using Dendroctonus valens, a monogamous bark beetle with typical biparental care, and Y-tube olfactometers, we provided males with a choice between two females and found strong evidence of odour-based male mate preference. We then tested whether this preference led to successful matings and if it had consequences for courtship displays and offspring fitness. Male and preferred female pairs had less aggressive courtship interactions, longer copulation times, constructed galleries faster, and had cleaner galleries. Preferred females had faster oviposition rates and larval development. Our study shows that, in D. valens, males choose females based on chemical cues and that the resulting male–female pairs have superior reproductive success.

Influence of translocation strategy and mating system on the genetic structure of a newly established population of island ptarmigan

Island populations and populations established by reintroductions are prone to extinction, in part because they are vulnerable to deterministic and stochastic phenomena associated with geographic isolation and small population size. As population size declines, reduced genetic diversity can result in decreased fitness and reduced adaptive potential, which may hinder short- or long-term population viability. We used 32 microsatellite markers to investigate the conservation genetics of a newly established population of Evermann’s Rock Ptarmigan (Lagopus muta evermanni) at Agattu Island, in the western Aleutian Archipelago, Alaska. We found low genetic diversity (observed heterozygosity = 0.41, allelic richness = 2.2) and a small effective population size (Ne = 28.6), but a relatively large Ne/N ratio = 0.55, which was attributed to multiple paternity in 80% of the broods and low reproductive skew among males (λ = 0.29). Moreover, successful breeding pairs were less related to each other than random male–female pairs. For conservation efforts based on reintroductions, a mating system with high rates of multiple paternity may facilitate retention of genetic diversity, thereby reducing the potential for inbreeding in small or isolated populations. Our results underscore the importance of quantifying genetic diversity and understanding the breeding behavior of translocated populations.