Male Dispersal Research Articles

Bi-parentally Inherited Genetic Evidence for Male-Biased Dispersal in Common Moorhen (Gallinula chloropus).

Dispersal is a life history trait that has relevant effect on both the dynamics and the genetics of species and sex-biased dispersal depends on how resource competition affects each of the sexes. In this study, a total of 210 blood samples including 121 Common Moorhen (Gallinula chloropus) females and 89 males were collected from 18 diverse areas during the breeding season. Based on 8 microsatellite markers analyses, we found that the most genetic diversities from female populations were higher than those from the males, where only 2 male individuals were identified as the long-distance dispersal. Analyses of sex-biased dispersal conducted over all sampling sites indicated that mAI (female mAI = 0.195, male mAI = - 0.265, P = 0.01), FST (female FST = 0.045, male FST = 0.026, P = 0.020), and r (female r = 0.118, male r = 0.064, P = 0.010) in females were all significantly higher than those in males at the 0.05 level, which suggested a male-biased dispersal pattern in this species. Our Mantel test results suggested a significant isolation-by-distance pattern for females but not for males, which corresponded to the more frequent dispersal and gene flow in males than in females. This dispersal pattern could be explained by the special life history trait and mating system that Common Moorhen pair formation occurs before they leave the flock in the spring to establish territories and its females initiate courtship more frequently than males and compete with each other to pair with small males with large fat reserves. The philopatric female could benefit most from knowledge of a particular area because they may win more intrasexual competitions in the breeding season and be able to produce more offspring if they are familiar with the local resources.

Short dispersal distance of males in a wild white-handed gibbon (Hylobates lar) population.

It has long been recognized that in gibbons both sexes disperse from the natal group. However, the fate of dispersed individuals was rarely documented. Here we provide the first detailed information on sex differences in dispersal patterns by analyzing the spatial genetic structure of a well-known white-handed gibbon (Hylobates lar) population. Mitochondrial DNA (mtDNA) and Y-chromosomal haplotypes, and autosomal microsatellite genotypes were determined for individuals of the Mo Singto study site, Khao Yai National Park, Thailand. Mantel tests for the three genetic marker types were performed for 17 gibbon groups comprising 23 adult males and 18 adult females. Significant positive Mantel correlations were observed for spatial distance and both autosomal microsatellite-based as well as Y-chromosomal haplotype-based genetic distance among adult males. Neighboring adult males tended to be genetically related and share Y-chromosomal haplotypes. Conversely, no significant Mantel correlations were observed either in autosomal microsatellites or mtDNA among adult females. Our results confirm, at a genetic level, hypotheses from long-term demographic observations that white-handed gibbon males of the Mo Singto population primarily disperse into adjacent groups. Instead, females disperse more opportunistically either to adjacent or more distant groups. This sex-specific difference reflects an apparent greater tolerance between males than between females. The higher tolerance of adult males allows the formation of stable multimale groups and facilitates male dispersal into an adjacent group. Stable multifemale groups have never been documented for white-handed gibbons probably due to feeding competition between females.

Should I stay or should I go? Movement of adult Triatoma sordida within the peridomestic area of a typical Brazilian Cerrado rural household

BackgroundChagas disease, or American trypanosomiasis, is an important neglected tropical illness caused by the flagellate protozoan Trypanosoma cruzi, which is primarily transmitted to humans by hematophagous insects of the subfamily Triatominae. Although knowledge on triatomine movement capabilities at the micro-geographical scale is of fundamental importance concerning the development of effective vector control strategies, it remains a poorly understood subject. Furthermore, survival rates and size estimates of natural populations are important topics to consider when evaluating transmission intensity.ResultsThe movement of adult Triatoma sordida within the peridomestic area of a rural Brazilian household was evaluated via mark-release-recapture assays. A total of 210 insects had their pronota marked with fluorescent dyes and were released at different distances from the chicken coop (two, five, ten and 20 m), and from the horse corral (27, 32, 35, 46 and 56 m). Recaptures occurred in three consecutive 15-day intervals. Specimens were successfully recaptured at all distances up to 32 m. Bayesian models were used to estimate recapture probability, survival rates (males vs females) and population size. Although recapture probability was inversely proportional to distance for both sexes, females were more affected by increased distance. On the other hand, no significant difference was detected in the survival rates between males and females in a 15-day period. Fisher-Ford and Bayesian models gave more accurate population size estimates than Lincoln method.ConclusionsTriatoma sordida adults were able to cover a distance of 32 m in 45 days. Recapture data modelling reveals that male dispersal was more effective suggesting that T. sordida males are more likely to contribute as potential colonizers of the peridomestic environment. Increasing the distance between the peridomestic structures and the sylvatic environment as much as possible appears to be a simple and feasible recommendation to reduce the contact rate between humans and infected bugs and ultimately Chagas disease transmission.

A familiar face with a novel behavior raises challenges for conservation: American mink in arid Patagonia and a critically endangered bird

Invasive American mink is a severe threat to endangered waterbird populations. In Europe and South America, control efforts have been increasing in the last decades. Mink has a proven acute impact on the Hooded Grebe, a critically endangered specialist of highland plateau lakes in Patagonia where a single mink attack can deplete up to 4% of the global population. We aimed to examine mink ecology in Austral Patagonia to inform ongoing control programs in the region and contribute to efforts elsewhere to counteract mink impact. We evaluated mink distribution at a regional scale and found that its distribution extends across the steppe-arid environment, often assumed to be an obstacle for mink colonization. Consequently, its current distribution fully overlaps with the Hooded Grebe breeding grounds. At a finer scale, we used 3 techniques to detect American mink at different times of the year and found a temporal sex-biased occupation-dispersion pattern: permanent presence of both sexes in areas around the plateaus used by grebes and upstream male biased dispersion in late summer (which leads young mink to the grebes' lakes). Therefore, plateau perimeters function as an invasion front that resets yearly. Lastly, from scat content analysis we detected a shift in mink diet from a generalist type in lowland rivers to a diet specialized on birds in highland lakes, where attacks are exclusively directed towards Hooded Grebes and where waterbird presence might be a determinant of mink presence (regardless of other prey). All of these findings have profound relevance for control schedules and priorities.

Factors affecting the mortality of Lumholtz's tree-kangaroo (Dendrolagus lumholtzi) by vehicle strike

Context Vehicle strike is a major issue where wildlife habitat is intersected by busy roads. Near Threatened Lumholtz’s tree-kangaroo (Dendrolagus lumholtzi) is a large (5–10 kg) semi-arboreal mammal found in populated rural and forested areas of north-eastern Australia. Warning signs, rope bridges and underpasses have not prevented ~20 animals being killed on the road each year. Aims To identify factors influencing Lumholtz’s tree-kangaroo vehicle strike to help inform mitigation options. Methods Citizen sightings (1998–2000) and 90 road-kills collected over 4.5 years on the Atherton Tablelands, Australia, were examined to determine the causes of vehicle strike in Lumholtz’s tree-kangaroo. The spatial distributions of sightings and road-kills were characterised using nearest-neighbour analysis, and the relationship between them was determined using a Bayesian approach that accounted for spatial autocorrelation. Gender, age, weight, season, rainfall, road and verge characteristics, traffic volumes, speed limits and mitigation measures were recorded to assess their influence on road-kill risk. Adequacy of speed limits to prevent collisions along road sections with more than four road-kills per 8 km (hazard zones) was assessed from visibility and stopping distances. Key results Vehicle strikes mainly affected male tree-kangaroos (2–5 years, 5.5–8 kg), occurred where live animals were most frequently sighted and were most likely on roads with narrow verges, low visibility and medium traffic volumes. Speed limits at hazard zones were inadequate to prevent collisions. Few warning signs corresponded with these zones, and road mortalities persisted where they did. Conclusions Unpredictable dispersal of young males and vehicle speeds unsuited to road conditions drive road mortalities in Lumholtz’s tree-kangaroo. Because tree-kangaroos do not appear to respond to existing mitigation measures, reducing traffic speeds, and increasing visibility, appear to be the most effective mitigation strategies for reducing tree-kangaroo road mortality. Implications Our findings suggest that tree-kangaroo road-kill can be reduced by reducing speed limits in line with government recommendations and increasing visibility by clearing road verges along sections of road with the highest tree-kangaroo mortality. Warning signage should be re-evaluated to determine whether its effectiveness can be improved.

Anthropogenic hive movements are changing the genetic structure of a stingless bee (Tetragonula carbonaria) population along the east coast of Australia

Across the world, the keeping of stingless bees is increasingly popular, providing commercial pollination, high-value honey and a rewarding pass time. The popularity of stingless beekeeping has resulted in large-scale anthropogenic movements of nests, sometimes from outside their native range. Colony movement has the potential to impact local populations via transfer of parasites and pathogens and gene flow across unnaturally large geographic scales. Tetragonula carbonaria is the most widespread and commonly kept stingless bee species in Australia. Concerns have been raised that large-scale artificial propagation of T. carbonaria colonies by Sydney beekeepers, from a small number of colonies that originated in south-east Queensland, may have two consequences. First, the managed population may be becoming increasingly inbred. Second, the wild population may be experiencing significant introgression of south-east Queensland genotypes, potentially diluting local adaptations to the Sydney environment and resulting in the loss of local alleles. Here we show, based on microsatellite and mitochondrial markers, that both the managed and wild Sydney populations are significantly different from the south-east Queensland population. Nonetheless there is evidence that introgression of south-east Queensland alleles is impacting the genetic structure of both wild and managed Sydney populations. The two Sydney populations are indistinguishable, suggesting two-way gene flow in Sydney consistent with expectations of gene flow via male dispersal. All populations have low inbreeding coefficients, suggesting that they are genetically healthy.

Insights on dispersal and recruitment paradigms: sex- and age-dependent variations in a nomadic breeder.

Sex- and age-dependence in recruitment and dispersal are often explained by costs arising from competition for holding a breeding territory over the years-a typical feature of species living in stable habitats. For instance, long-lived birds with male territoriality often exhibit large variation in recruitment age and higher dispersal in females and young individuals. As a corollary, we expected that species with ephemeral habitat suitability, and hence nomadic breeding, would show weak age- and sex-dependence in dispersal and low variation in recruitment age, because territory ownership is not maintained over the years. In addition, the higher cost of reproduction in females might not be (over)compensated for by costs of territoriality in males. Accordingly, females would recruit later than males. We explored these variations using multievent capture-recapture models over 13years, 3479 (2392 sexed) slender-billed gulls (Chroicocephalus genei) and 45 colony sites along the French Mediterranean coast. As expected, variability in recruitment age was low with males recruiting earlier than females. Nonetheless, dispersal in and out of the study area decreased with age and was slightly higher in males than in females. Decreased dispersal with age might result from foraging benefits associated with increased spatial familiarity. Higher dispersal in males might be explained by a male-biased sex ratio or higher philopatry benefits in females (arising from their higher cost of reproduction). Sex- and age-dependent dispersal and recruitment may thus occur in the absence of year-to-year breeding territory ownership, which stresses the importance of considering other processes in shaping recruitment and dispersal patterns.

Conservation implications for dingoes from the maternal and paternal genome: Multiple populations, dog introgression, and demography.

It is increasingly common for apex predators to face a multitude of complex conservation issues. In Australia, dingoes are the mainland apex predator and play an important role in ecological functioning. Currently, however, they are threatened by hybridization with modern domestic dogs in the wild. As a consequence, we explore how increasing our understanding of the evolutionary history of dingoes can inform management and conservation decisions. Previous research on whole mitochondrial genome and nuclear data from five geographical populations showed evidence of two distinct lineages of dingo. Here, we present data from a broader survey of dingoes around Australia using both mitochondrial and Y chromosome markers and investigate the timing of demographic expansions. Biogeographic data corroborate the presence of at least two geographically subdivided genetic populations, southeastern and northwestern. Demographic modeling suggests that dingoes have undergone population expansion in the last 5,000 years. It is not clear whether this stems from expansion into vacant niches after the extinction of thylacines on the mainland or indicates the arrival date of dingoes. Male dispersal is much more common than female, evidenced by more diffuse Y haplogroup distributions. There is also evidence of likely historical male biased introgression from domestic dogs into dingoes, predominately within southeastern Australia. These findings have critical practical implications for the management and conservation of dingoes in Australia; particularly a focus must be placed upon the threatened southeastern dingo population.

Group Living and Male Dispersal Predict the Core Gut Microbiome in Wild Baboons.

The mammalian gut microbiome plays a profound role in the physiology, metabolism, and overall health of its host. However, biologists have only a nascent understanding of the forces that drive inter-individual heterogeneity in gut microbial composition, especially the role of host social environment. Here we used 178 samples from 78 wild yellow baboons (Papio cynocephalus) living in two social groups to test how host social context, including group living, social interactions within groups, and transfer between social groups (e.g., dispersal) predict inter-individual variation in gut microbial alpha and beta diversity. We also tested whether social effects differed for prevalent "core" gut microbial taxa, which are thought to provide primary functions to hosts, versus rare "non-core" microbes, which may represent relatively transient environmental acquisitions. Confirming prior studies, we found that each social group harbored a distinct gut microbial community. These differences included both non-core and core gut microbial taxa, suggesting that these effects are not solely driven by recent gut microbial exposures. Within social groups, close grooming partners had more similar core microbiomes, but not non-core microbiomes, than individuals who rarely groomed each other, even controlling for kinship and diet similarity between grooming partners. Finally, in support of the idea that the gut microbiome can be altered by current social context, we found that the longer an immigrant male had lived in a given social group, the more closely his gut microbiome resembled the gut microbiomes of the group's long-term residents. Together, these results reveal the importance of a host's social context in shaping the gut microbiome and shed new light onto the microbiome-related consequences of male dispersal.

Putative origin and maternal relatedness of male sperm whales (Physeter macrocephalus) recently stranded in the North Sea

The globally distributed sperm whale (Physeter macrocephalus) has a partly matrilineal social structure with predominant male dispersal. At the beginning of 2016, a total of 30 male sperm whales stranded in five different countries bordering the southern North Sea. It has been postulated that these individuals were on a migration route from the north to warmer temperate and tropical waters where females live in social groups. By including samples from four countries (n=27), this event provided a unique chance to genetically investigate the maternal relatedness and the putative origin of these temporally and spatially co-occuring male sperm whales. To utilize existing genetic resources, we sequenced 422bp of the mitochondrial control region, a molecular marker for which sperm whale data are readily available from the entire distribution range. Based on four single nucleotide polymorphisms (SNPs) within the mitochondrial control region, five matrilines could be distinguished within the stranded specimens, four of which matched published haplotypes previously described in the Atlantic. Among these male sperm whales, multiple matrilineal lineages co-occur. We analyzed the population differentiation and could show that the genetic diversity of these male sperm whales is comparable to the genetic diversity in sperm whales from the entire Atlantic Ocean. We confirm that within this stranding event, males do not comprise maternally related individuals and apparently include assemblages of individuals from different geographic regions.

Alu Insertion Polymorphisms as Evidence for Population Structure in Baboons.

Male dispersal from the natal group at or near maturity is a feature of most baboon (Papio) species. It potentially has profound effects upon population structure and evolutionary processes, but dispersal, especially for unusually long distances, is not readily documented by direct field observation. In this pilot study, we investigate the possibility of retrieving baboon population structure in yellow (Papio cynocephalus) and kinda (Papio kindae) baboons from the distribution of variation in a genome-wide set of 494 Alu insertion polymorphisms, made available via the recently completed Baboon Genome Analysis Consortium. Alu insertion variation in a mixed population derived from yellow and olive (Papio anubis) baboons identified each individual’s proportion of heritage from either parental species. In an unmixed yellow baboon population, our analysis showed greater similarity between neighboring than between more distantly situated groups, suggesting structuring of the population by male dispersal distance. Finally (and very provisionally), an unexpectedly sharp difference in Alu insertion frequencies between members of neighboring social groups of kinda baboons suggests that intergroup migration may be more rare than predicted in this little known species.

Sex-biased dispersal is independent of sex ratio in a semiaquatic insect

Dispersal influences a variety of ecological and evolutionary dynamics including metapopulation persistence and local adaptation. Sex-biased dispersal evolves when the costs and benefits associated with dispersal differ between the sexes. These costs and benefits may be fixed, resulting in a consistent pattern of sex-biased dispersal within species whereby one sex always disperses more and/or further than the other. Alternatively, the costs and benefits may vary depending on the intensity of competition experienced by the two sexes. In this case, the direction of the sex bias may be plastic and depend on the sex ratio of the population. In the current study, we asked whether a semiaquatic, flight capable insect (Notonecta undulata) exhibits sex-biased dispersal and whether the strength of intrasexual competition experienced by males and females determines the direction of the sex bias. We conducted a mesocosm experiment in which we manipulated the population sex ratio and measured the probability of dispersal for males and females. We found that while both sexes dispersed, male dispersal rates were higher, and this pattern was independent of sex ratio. This suggests that fixed sex-specific dispersal costs and/or benefits are likely to be more important determinants of sex-biased dispersal in notonectids than population sex ratio. Dispersal is the process by which individuals move through space and cause gene flow and therefore is a major factor determining the distribution of individuals, populations, species, and alleles—a topic which is one of the core themes in ecology. Dispersers commonly differ from non-dispersers in a variety of phenotypes, including sex. Sex-biased dispersal may have important implications for the populations that send out and receive dispersers, because males and females have different impacts on populations. We explored whether sex-specific dispersal behavior in an insect (Notonecta undulata) changes depending on how intensely individuals have to compete for resources (e.g., food, mates) with individuals of the same sex. We found that males dispersed more, and this was true regardless of which sex experienced stronger intrasexual competition. This suggests that males experience lower costs and/or greater benefits from dispersing than do females.

Sex-specific genetic analysis indicates low correlation between demographic and genetic connectivity in the Scandinavian brown bear (Ursus arctos).

The degree of gene flow within and among populations, i.e. genetic population connectivity, may closely track demographic population connectivity. Alternatively, the rate of gene flow may change relative to the rate of dispersal. In this study, we explored the relationship between genetic and demographic population connectivity using the Scandinavian brown bear as model species, due to its pronounced male dispersal and female philopatry. Thus, we expected that females would shape genetic structure locally, whereas males would act as genetic mediators among regions. To test this, we used eight validated microsatellite markers on 1531 individuals sampled noninvasively during country-wide genetic population monitoring in Sweden and Norway from 2006 to 2013. First, we determined sex-specific genetic structure and substructure across the study area. Second, we compared genetic differentiation, migration/gene flow patterns, and spatial autocorrelation results between the sexes both within and among genetic clusters and geographic regions. Our results indicated that demographic connectivity was not a reliable indicator of genetic connectivity. Among regions, we found no consistent difference in long-term gene flow and estimated current migration rates between males and females. Within regions/genetic clusters, only females consistently displayed significant positive spatial autocorrelation, indicating male-biased small-scale dispersal. In one cluster, however, males showed a dispersal pattern similar to females. The Scandinavian brown bear population has experienced substantial recovery over the last decades; however, our results did not show any changes in its large-scale population structure compared to previous studies, suggesting that an increase in population size and dispersal of individuals does not necessary lead to increased genetic connectivity. Thus, we conclude that both genetic and demographic connectivity should be estimated, so as not to make false assumptions about the reality of wildlife populations.

Male Dispersal Pattern in Golden Snub-nosed Monkey (Rhinopithecus roxellana) in Qinling Mountains and its Conservation Implication

Golden snub-nosed monkey (Rhinopithecus roxellana) is one of the most endangered primate species found in China, exhibiting multilevel society consisting of several one-male-females together with their offspring units (OMU), and all-male units (AMU). Female dispersal patterns of the species within herd have been well documented, whereas those of the males within or between herds are still poorly understood. Our results based a long-term observation indicate that more than half of sub-adult males, and half of the deposed males that stayed a short period in OMU disperse between herds, three of them established their own OMU in new herd after the dispersal. Smaller number of the sub-adult and adult males, compared with adult females, stayed in natal herd, implying sub-adult males started dispersing and male-biased dispersal occurred between herds. High frequencies of resident males were wounded as their OUMs were taken over, and resident males co-operation defend bachelor males were found. Mating competition among males within the herd may have contributed to the scenarios of male-biased dispersal. The results also suggest that maintaining connection between isolated herds and establishing the corridors among the fragmented habitats for the species will greatly benefit increasing its gene flow and promoting conservation status.

Asexual queen succession mediates an accelerated colony life cycle in the termite Silvestritermes minutus.

Mixed modes of reproduction, combining sexual processes with thelytokous parthenogenesis, occur in all major clades of social insects. In several species of termites, queens maximize their genetic input into nondispersing replacement queens through parthenogenesis, while maintaining genetically diverse sterile offspring and dispersing reproductives via sexual reproduction. This so-called asexual queen succession (AQS) has multiple independent origins and its presumed advantages are diverse as well, ranging from multiplication of colony reproductive potential to extension of its lifespan beyond that of the foundress. However, how AQS shapes colony life cycles under natural conditions remains poorly known. The neotropical termite Silvestritermes minutus inhabits small but conspicuous nests, offering a unique opportunity to investigate the impact of AQS on life history. We report on its breeding system, life cycle and sex allocation using social structure census in 137 nests and genotyping of 12 colonies at 12 microsatellite loci. We show that colonies are established by an outbred pair of primary reproductives. In less than 2years, the foundress is replaced by multiple neotenic queens, arising mostly through automixis with central fusion. Sterile castes, male and most (93%) female dispersers are produced sexually. Colony reproduction is usually restricted to a single dispersal of alates with unbiased sex ratio, taking place after 3years. We conclude that S.minutus benefits from AQS to maximize colony growth rate and alate production within a very short life cycle rather than to extend colony lifespan. This highlights the versatile role of AQS in different cases of its polyphyletic origin.

Development of Microsatellites for Population Genetic Analyses of the Granulate Ambrosia Beetle (Coleoptera: Curculionidae).

Limited male dispersal and local mating in ambrosia beetles are expected to result in extreme inbreeding and highly structured populations. In this study, we developed microsatellite markers for the granulate ambrosia beetle, Xylosandrus crassiusculus (Motschulsky), for use in future studies into population and family structure of this invasive pest species. We employed de novo next-generation sequencing to generate whole genome shotgun sequences for the characterization of microsatellite loci. Approximately 6% of the 84,024 contigs generated from Hi-Seq Illumina 2x250bp sequencing contained microsatellites with at least four repeats of di-, tri-, tetra-, penta-, and hexamers. Primers were synthesized for 40 microsatellite loci with trimer repeat units. Twenty-four primer pairs yielded consistent PCR products of unique loci and were validated for population genetic application using three sample groups each containing 20 X. crassiusculus individuals from Mississippi. Thirteen loci were found to be polymorphic with up to five alleles per population. The two beetle sample groups from Pearl River County (Poplarville and McNeill) belonged genetically to the same population. The population from Lamar County (Purvis) was genetically distinct, separated by a moderate genetic distance (FST = 0.11) and five unique alleles (with >5% frequency). Consistent with the perceived mating structure (incest of females with flightless males), the populations showed homozygote excess at most loci, as indicated by the coefficients of inbreeding (FIT = 0.45 and FIS = 0.37) and high mean relatedness among individuals (r = 0.15).

Wolf dispersal in the Rocky Mountains, Western United States: 1993–2008

ABSTRACTGray wolves (Canis lupus) were extirpated from the northern Rocky Mountains (NRM) of the United States by the 1930s. Dispersing wolves from Canada naturally recolonized Montana and first denned there in 1986. In 1995 and 1996, the United States Fish and Wildlife Service reintroduced 66 wolves into central Idaho and Yellowstone National Park. By 2008, there were ≥1,655 wolves in ≥217 packs, including 95 breeding pairs in the NRM. From 1993–2008, we captured and radio‐collared 1,681 wolves and documented 297 radio‐collared wolves dispersing as lone individuals. We monitored dispersing wolves to determine their pack characteristics (i.e., pack size and surrounding pack density) before and after dispersal, their reproductive success, and eventual fate. We calculated summary statistics for characteristics of wolf dispersal (i.e., straight‐line distance, age, time of year, sex ratio, reproduction, and survival), and we tested these characteristics for differences between sexes and age groups. Approximately, 10% of the known wolf population dispersed annually. The sex ratio of dispersals favored males (169 M, 128 F), but fewer dispersed males reproduced (28%,n = 47) than females (42%,n = 54). Fifty‐nine percent of all dispersers of known age were adults (n = 156), 37% were yearlings (n = 99), and 4% were pups (n = 10). Mean age at dispersal for males (32.8 months) was not significantly different (P = 0.88) than for females (32.1 months). Yellowstone National Park had a significant positive effect on dispersal rate. Pack density in a wolf's natal population had a negative effect on dispersal rate when the entire NRM population was considered. The mean NRM pack size (6.9) from 1993 to 2008 was smaller than the mean size of packs (10.0) from which wolves dispersed during that time period (P < 0.001); however, pack size was not in our most supported model. Dispersals occurred throughout the year but generally increased in the fall and peaked in January. The mean duration of all dispersals was 5.5 months. Radio‐collared wolves dispersed between Montana, Idaho, and Wyoming to other adjacent states, and between the United States and Canada throughout the study. Mean straight‐line distance between starting and ending points for dispersing males (98.1 km) was not significantly different than females (87.7 km;P = 0.11). Ten wolves (3.4%) dispersed distances >300 km. On average, dispersal distance decreased later in the study (P = 0.006). Sex, survival rate in the natal population, start date, dispersal distance, and direction were not significant predictors of dispersal rate or successful dispersal. Wolves that formed new packs were >11 times more likely to reproduce than those that joined packs and surrounding pack density had a negative effect on successful dispersal. Dispersal behavior seems to be innate in sexually mature wolves and thereby assures that genetic diversity will remain high and help conserve the NRM wolf population. © 2017 The Wildlife Society.

The Influence of Incubation Conditions and Sex on Growth and Dispersal in Hatchling Lizards

AbstractDispersal is a critical process that has profound influence on ecological and evolutionary processes. Many proximate factors influence natal dispersal, but it is currently unclear whether the conditions experienced during incubation play an important role. We manipulated incubation temperature and used mark–recapture of released hatchlings to test this hypothesis. We tested this hypothesis on the prairie lizard (Sceloporus consobrinus) using two experimental islands in a local reservoir. Incubation conditions influenced some aspects of hatchling morphology, but had little influence on the probability of dispersal. As generally predicted for a polygynous species, males were more likely to disperse than females; however, the growth rate of dispersing vs. resident individuals varied depending on sex. Dispersive male lizards did not grow faster than resident males, whereas female dispersers grew significantly slower than resident females. Although our study was not specifically designed to test for differential costs of dispersal for males and females, this pattern is consistent with recent research demonstrating sex‐specific fitness costs of dispersal.

Male wage inequality and marital dissolution: Is there a link?

AbstractAfter almost a century‐long pattern of rising marital instability, divorce rates levelled off in 1980 and have been declining ever since. The timing of deceleration and decline in the rates of marital dissolution interestingly coincides with a period of substantial growth in wage inequality. This paper establishes a novel connection between the two phenomena and discusses potential explanations for the underlying link. Using female marital histories in a duration analysis framework combined with regional and temporal variation in the pattern of male wage dispersion, I show that inequality has a significant stabilizing effect on the marriage. Quantitatively, increases in male wage dispersion can roughly explain up to 30% of the fall in the mean separation probability between 1979 and 1990. Several plausible explanations are discussed: changes in spousal labour supplies, female wage inequality, income uncertainty, social capital as well as a hypothesis where inequality renders the option to divorce less attractive by making remarriage more difficult.

Multilocus Intron Trees Reveal Extensive Male-Biased Homogenization of Ancient Populations of Chamois (Rupicapra spp.) across Europe during Late Pleistocene.

The inferred phylogenetic relationships between organisms often depend on the molecular marker studied due to the diverse evolutionary mode and unlike evolutionary histories of different parts of the genome. Previous studies have shown conflicting patterns of differentiation of mtDNA and several nuclear markers in chamois (genus Rupicapra) that indicate a complex evolutionary picture. Chamois are mountain caprine that inhabit most of the medium to high altitude mountain ranges of southern Eurasia. The most accepted taxonomical classification considers two species, R. pyrenaica (with the subspecies parva, pyrenaica and ornata) from southwestern Europe and R. rupicapra (with the subspecies cartusiana, rupicapra, tatrica, carpatica, balcanica, asiatica and caucasica) from northeastern Europe. Phylogenies of mtDNA revealed three very old clades (from the early Pleistocene, 1.9 Mya) with a clear geographical signal. Here we analyze a set of 23 autosomal introns, comprising 15,411 nucleotides, in 14 individuals covering the 10 chamois subspecies. Introns offered an evolutionary scenario that contrasts with mtDNA. The nucleotidic diversity was 0.0013± 0.0002, at the low range of what is found in other mammals even if a single species is considered. A coalescent multilocus analysis with *BEAST indicated that introns diversified 88 Kya, in the late Pleistocene, and the effective population size at the root was lower than 10,000 individuals. The dispersal of some few migrant males should have rapidly spread trough the populations of chamois, given the homogeneity of intron sequences. The striking differences between mitochondrial and nuclear markers can be attributed to strong female philopatry and extensive male dispersal. Our results highlight the need of analyzing multiple and varied genome components to capture the complex evolutionary history of organisms.