Restoration of genetic connectivity among Northern Rockies wolf populations

Probably no conservation genetics issue is currently more controversial than the question of whether grey wolves (Canis lupus) in the Northern Rockies have recovered to genetically effective levels. Following the dispersal‐based recolonization of Northwestern Montana from Canada, and reintroductions to Yellowstone and Central Idaho, wolves have vastly exceeded population recovery goals of 300 wolves distributed in at least 10 breeding pairs in each of Wyoming, Idaho and Montana. With >1700 wolves currently, efforts to delist wolves from endangered status have become mired in legal battles over the distinct population segment (DPS) clause of the Endangered Species Act (ESA), and whether subpopulations within the DPS were genetically isolated. An earlier study by vonHoldt et al. (2008) suggested Yellowstone National Park wolves were indeed isolated and was used against delisting in 2008. Since then, wolves were temporarily delisted, and a first controversial hunting season occurred in fall of 2009. Yet, concerns over the genetic recovery of wolves in the Northern Rockies remain, and upcoming District court rulings in the summer of 2010 will probably include consideration of gene flow between subpopulations. In this issue of Molecular Ecology, vonHoldt et al. (2010) conduct the largest analysis of gene flow and population structure of the Northern Rockies wolves to date. Using an impressive sampling design and novel analytic methods, vonHoldt et al. (2010) show substantial levels of gene flow between three identified subpopulations of wolves within the Northern Rockies, clarifying previous analyses and convincingly showing genetic recovery.     

Genetic structure of the wild boar population in Portugal: Evidence of a recent bottleneck

The present study assesses the degree of genetic structure and the presence of recent genetic bottlenecks in the wild boar population in Portugal. One hundred and ten individuals were sampled after capture during organised legal drive hunts, conducted in 58 municipalities across the continental territory, during the game seasons of 2002/2003 and 2003/2004. Individuals were genetically typed at six microsatellite loci using multiplex PCR amplification. Significant deviations from Hardy–Weinberg equilibrium were found for the total population of wild boar in Portugal. Wild boar population genetic structure was assessed using Bayesian methods, suggesting the existence of three subpopulations (North, Centre and South). Tests were conducted to detect the presence of potential migrants and hybrids between subpopulations. After exclusion of these individuals, three sets of wild boars representative of respective subpopulations were distinguished and tested for the effects of recent bottlenecks. Genetic distances between pairs of subpopulations were quantified using F_ST and R_ST estimators, revealing a variation of 0.138–0.178 and 0.107–0.198, respectively. On the basis of genetic and distribution data for Portuguese wild boar from the beginning of the 20th century, a model of strong demographic decline and contraction to isolated refuge areas at the national level, followed by a recovery and expansion towards former distribution limits is suggested. Some evidence points to present admixture among subpopulations in contact areas.     

Captive breeding and the reintroduction of Mexican and red wolves

Mexican and red wolves were both faced with extinction in the wild until captive populations were established more than two decades ago. These captive populations have been successfully managed genetically to minimize mean kinship and retain genetic variation. Descendants of these animals were subsequently used to start reintroduced populations, which now number about 40-50 Mexican wolves in Arizona and New Mexico and about 100 red wolves in North Carolina. The original captive Mexican wolf population was descended from three founders. Merging this lineage with two other captive lineages, each with two founders, has been successfully carried out in the captive population and is in progress in the reintroduced population. This effort has resulted in increased fitness of cross-lineage wolves, or genetic rescue, in both the captive and reintroduced populations. A number of coyote-red wolf hybrid litters were observed in the late 1990s in the reintroduced red wolf population. Intensive identification and management efforts appear to have resulted in the elimination of this threat. However, population reintroductions of both Mexican and red wolves appear to have reached numbers well below the generally recommended number for recovery and there is no current effort to re-establish other populations.     

Genetic diversity and population structure of the threatened Bliss Rapids snail (Taylorconcha serpenticola)

1. The Bliss Rapids snail is a federally listed yet poorly known small caenogastropod which lives in the Snake River drainage (main stem river and spring‐fed tributaries) of south‐central Idaho. The construction of three large dams along this portion of the Snake River during the 20th century is thought to have fragmented a single, ancestral population of this species into genetically isolated subunits that are vulnerable to extinction. We assessed variation of 11 microsatellite loci within and among 29 samples (820 snails) from across the entire range of the Bliss Rapids snail to assess genetic structure and test whether habitat fragmentation resulting from dam construction has impacted population connectivity. 2. The overall F_ST (0.15133, P < 0.05) and pairwise comparisons among samples (384/406 significant) indicated extensive population subdivision in general. A consistent trend of isolation by distance trend was not detected by Mantel tests. We found no evidence of reduced genetic diversity attributable to segmentation of the Snake River, and genetic variation among portions of drainage separated by the dams was not significant. Population structuring in spring–tributary habitats was considerably greater than in the main stem river as evidenced by differences in F_ST (0.18370, 0.06492) and the number of private alleles detected (16, 4), and by the results of an assignment test (69.4%, 58.7% correctly classified to sample of origin) and Bayesian genetic clustering algorithm. 3. Our results provide no evidence that dam construction has genetically impacted extant populations of the Bliss Rapids snail. We speculate that the generally weaker genetic structuring of riverine populations of this species is a result of passive dispersal within the water column, which may enable occasional passage through the dams. The somewhat stronger structuring observed in a portion of the river (Shoshone reach) which receives discharge from many springs may be due to local mixing of main stem and more highly differentiated tributary populations. Our findings parallel recent, genetically based studies of other western North American freshwater gastropods that also demonstrate complex population structure that conflicts with traditional concepts of dispersal ability and sensitivity to putative barriers.     

Fine‐scale genetic structure in an eastern Alpine black grouse Tetrao tetrix metapopulation

Understanding genetic consequences of habitat fragmentation is crucial for the management and conservation of wildlife populations, especially in case of species sensitive to environmental changes and landscape alteration. In central Europe, the Alps are the core area of black grouse Tetrao tetrix distribution. There, black grouse dispersal is limited by high altitude mountain ridges and recent black grouse habitats are known to show some degree of natural fragmentation. Additionally, substantial anthropogenic fragmentation has occurred within the past ninety years. Facing losses of peripheral subpopulations and ongoing range contractions, we explored genetic variability and the fine‐scale genetic structure of the Alpine black grouse metapopulation at the easternmost fringe of the species’ Alpine range. Two hundred and fifty tissue samples and non‐invasive faecal and feather samples of eleven a priori defined subpopulations were used for genetic analysis based on nine microsatellite loci. Overall, eastern Alpine black grouse show similar amounts of genetic variation (H_O = 0.65, H_E = 0.66) to those found in more continuous populations like in Scandinavia. Despite of naturally and anthropogenically fragmented landscapes, genetic structuring was weak (global F_ST < 0.05), suggesting that the actual intensity of habitat fragmentation does not completely hamper dispersal, but probably restricts it to some extent. The most peripheral subpopulations at the edge of the species range show signs of genetic differentiation. The present study gives new insights into the population genetic structure of black grouse in the eastern Alps and provides a more fine‐scale view of genetic structure than previously available. Our findings will contribute to monitor the current and future status of the population under human pressures and to support supra‐regional land use planning as well as decision making processes in responsibilities of public administration.     

Genetic Diversity and Divergence among Bighorn Sheep from Reintroduced Herds in Washington and Idaho

Bighorn sheep (Ovis canadensis) populations in the western United States have undergone widespread declines and extirpations since the late nineteenth century as a consequence of introduced diseases, competition with livestock, and unregulated hunting. Washington, Idaho, USA, and British Columbia, Canada were historically thought to be occupied by 2 bighorn lineages or subspecies: Rocky Mountain (O. c. canadensis) and California (O. c. californiana). The putative California lineage was completely extirpated in the United States, and reintroductions to reestablish populations were sourced directly or indirectly from a single region in southern British Columbia. Restoration efforts have attempted to maintain the diversity and divergence of these 2 lineages, sometimes referred to as subspecies although taxonomic classifications have changed over time. In this study we describe genetic variation in a subset of native and reintroduced herds of California and Rocky Mountain bighorn sheep. We examined genetic diversity and divergence between bighorn sheep herds using 15 microsatellite loci, including 4 loci linked to genes involved in immune function. We analyzed 504 samples from reintroduced herds in Washington (n = 10 California herds, n = 4 Rocky Mountain herds) and Idaho (n = 5 California), and source herds in Oregon (n = 1 Rocky Mountain) and British Columbia (n = 5 California, 1 Rocky Mountain). Genetic structure reflected known reintroduction history, and geographic proximity also was associated with decreased genetic divergence. Herds in Washington and Idaho sourced from California bighorn sheep were less genetically diverse than those sourced from Rocky Mountain herds. Also, levels of relatedness within and across California herds were higher than in Rocky Mountain herds and similar to what would be expected for full and half siblings. Lower diversity and higher relatedness among California herds is a concern for long-term fitness and likely related to past population bottlenecks, fewer source populations, and management history, such as entirely sourcing California herds from British Columbia. Genetic divergence of neutral loci between California and Rocky Mountain herds was greater than that of adaptive loci, potentially indicating that balancing selection has maintained similar genetic diversity across lineages in loci associated with immune and other adaptive functions. Thus, we recommend future reintroductions and augmentations should continue to use source populations from the appropriate California or Rocky Mountain lineage to avoid potential outbreeding depression and maintain possible adaptive differences. This could be accomplished by obtaining sheep from ≥1 source within the genetic lineage, while avoiding sourcing from admixed herds. Future work encompassing a broader geographic sampling of populations and a greater portion of the genome is necessary to better evaluate the degree to which contemporary divergence between lineages is associated with recent founder effects and genetic isolation or evolutionary adaptation. © 2021 The Wildlife Society     

Similarity in temporal variation in sex‐biased dispersal over short and long distances in the dark‐eyed junco,Junco hyemalis

Patterns of sex‐biased dispersal (SBD) are typically consistent within taxa, for example female‐biased in birds and male‐biased in mammals, leading to theories about the evolutionary pressures that lead to SBD. However, generalizations about the evolution of sex biases tend to overlook that dispersal is mediated by ecological factors that vary over time. We examined potential temporal variation in between‐ and within‐population dispersal over an 11‐year period in a bird, the dark‐eyed junco (Junco hyemalis). We measured between‐population dispersal patterns using genetic assignment indices and found yearly variation in which sex was more likely to have immigrated. When we measured within‐population spatial genetic structure and mark–recapture dispersal distances, we typically found yearly SBD patterns that mirrored between‐population dispersal, indicating common eco‐evolutionary causes despite expected differences due to the scale of dispersal. However, in years without detectable between‐population sex biases, we found genetic similarity between nearby males within our population. This suggests that, in certain circumstances, ecological pressures may act on within‐population dispersal without affecting dispersal between populations. Alternatively, current analytical tools may be better able to detect within‐population SBD. Future work will investigate potential causes of the observed temporal variation in dispersal patterns and whether they have greater effects on within‐population dispersal.     

Spatial genetic and morphologic structure of wolves and coyotes in relation to environmental heterogeneity in a Canis hybrid zone

Eastern wolves have hybridized extensively with coyotes and gray wolves and are listed as a ‘species of special concern’ in Canada. However, a distinct population of eastern wolves has been identified in Algonquin Provincial Park (APP) in Ontario. Previous studies of the diverse Canis hybrid zone adjacent to APP have not linked genetic analysis with field data to investigate genotype‐specific morphology or determine how resident animals of different ancestry are distributed across the landscape in relation to heterogeneous environmental conditions. Accordingly, we studied resident wolves and coyotes in and adjacent to APP to identify distinct Canis types, clarify the extent of the APP eastern wolf population beyond the park boundaries and investigate fine‐scale spatial genetic structure and landscape–genotype associations in the hybrid zone. We documented three genetically distinct Canis types within the APP region that also differed morphologically, corresponding to putative gray wolves, eastern wolves and coyotes. We also documented a substantial number of hybrid individuals (36%) that were admixed between 2 or 3 of the Canis types. Breeding eastern wolves were less common outside of APP, but occurred in some unprotected areas where they were sympatric with a diverse combination of coyotes, gray wolves and hybrids. We found significant spatial genetic structure and identified a steep cline extending west from APP where the dominant genotype shifted abruptly from eastern wolves to coyotes and hybrids. The genotypic pattern to the south and northwest was a more complex mosaic of alternating genotypes. We modelled genetic ancestry in response to prey availability and human disturbance and found that individuals with greater wolf ancestry occupied areas of higher moose density and fewer roads. Our results clarify the structure of the Canis hybrid zone adjacent to APP and provide unique insight into environmental conditions influencing hybridization dynamics between wolves and coyotes.     

Genetic consequences of habitat fragmentation and loss: the case of the Florida black bear (<Emphasis Type="Italic">Ursus americanus floridanus</Emphasis>)

Habitat loss and fragmentation can influence the genetic structure of biological populations. We studied the genetic consequences of habitat fragmentation in Florida black bear (Ursus americanus floridanus) populations. Genetic samples were collected from 339 bears, representing nine populations. Bears were genotyped for 12 microsatellite loci to estimate genetic variation and to characterize genetic structure. None of the nine study populations deviated from Hardy–Weinberg equilibrium. Genetic variation, quantified by mean expected heterozygosity (H _E), ranged from 0.27 to 0.71 and was substantially lower in smaller and less connected populations. High levels of genetic differentiation among populations (global F _ST = 0.224; global R _ST = 0.245) suggest that fragmentation of once contiguous habitat has resulted in genetically distinct populations. There was no isolation-by-distance relationship among Florida black bear populations, likely because of barriers to gene flow created by habitat fragmentation and other anthropogenic disturbances. These factors resulted in genetic differentiation among populations, even those that were geographically close. Population assignment tests indicated that most individuals were genetically assigned to the population where they were sampled. Habitat fragmentation and anthropogenic barriers to movement appear to have limited the dispersal capabilities of the Florida black bear, thereby reducing gene flow among populations. Regional corridors or translocation of bears may be needed to restore historical levels of genetic variation. Our results suggest that management actions to mitigate genetic consequences of habitat fragmentation are needed to ensure long-term persistence of the Florida black bear.     

Population structure of the olive flounder (Paralichthys olivaceus) in Korea inferred from microsatellite marker analysis

The population structure of olive flounder Paralichthys olivaceus was estimated using nine polymorphic microsatellite (MS) loci in 459 individuals collected from eight populations, including five wild and three hatchery populations in Korea. Genetic variation in hatchery (mean number of alleles per locus, A = 10·2–12·1; allelic richness, A_R = 9·3–10·1; observed heterozygosity, H_O = 0·766–0·805) and wild (mean number of alleles per locus, A = 11·8–19·6; allelic richness, A_R = 10·9–16·1; observed heterozygosity, H_O = 0·820–0·888) samples did not differ significantly, suggesting a sufficient level of genetic variation in these well‐managed hatchery populations, which have not lost a substantial amount of genetic diversity. Neighbour‐joining tree and principal component analyses showed that genetic separation between eastern and pooled western and southern wild populations in Korea was probably influenced by restricted gene flow between regional populations due to the barrier effects of sea currents. The pooled western and southern populations are genetically close, perhaps because larval dispersal may depend on warm currents. One wild population (sample from Wando) was genetically divergent from the main distribution, but it was genetically close to hatchery populations, indicating that the genetic composition of the studied populations may be affected by hydrographic conditions and the release of fish stocks. The estimated genetic population structure and potential applications of MS markers may aid in the proper management of P. olivaceus populations.     

POPULATION STRUCTURE AND GENETIC DIFFERENTIATION IN NATIVE AND INTRODUCED POPULATIONS OF DESCHAMPSIA CAESPITOSA (POACEAE) IN THE COLORADO ALPINE

Deschampsia caespitosa is a widespread grass common in moist areas of the alpine tundra of the Rocky Mountains. Enzyme electrophoresis was used to examine population genetic structure along two soil moisture gradients in Rocky Mountain National Park, Colorado. Introduced plants used in a revegetation project were also sampled at one of the sites. At both sites, there were significant differences among subpopulations in allele frequencies, but these differences were distributed in a patchy fashion and were not correlated with the apparent soil moisture gradients. The degree of genetic subdivision differed between the two sites. At one site, gene flow appeared to be high and differences in allele frequencies are attributed to selection in a mosaic environment. At the other site, gene flow appeared more restricted and differences in allele frequencies between subpopulations are attributed to selection and limited gene flow acting simultaneously. Overall, 15% of the genetic variability is between subpopulations and gene flow is high, even between subpopulations separated by up to 1.5 km, but local conditions can apparently limit gene flow and increase the degree of genetic subdivision. The mean genetic distance between introduced plants and the native subpopulations was significantly higher than the mean genetic distance between all other subpopulations. Despite the high gene flow apparent in alpine tundra subpopulations of Deschampsia caespitosa, significant genetic structuring of these subpopulations has developed.     

Scale‐dependent post‐establishment spread and genetic diversity in an invading mollusc in South America

Aims Our study aimed to characterize the dispersal dynamics and population genetic structure of the introduced golden mussel Limnoperna fortunei throughout its invaded range in South America and to determine how different dispersal methods, that is, human‐mediated dispersal and downstream natural dispersal, contribute to genetic variation among populations. Location Paraná–Uruguay–Río de la Plata watershed in Argentina, Brazil, Paraguay and Uruguay. Methods We performed genetic analyses based on a comprehensive sampling strategy encompassing 22 populations (N = 712) throughout the invaded range in South America, using the mitochondrial cytochrome c oxidase subunit I (COI) gene and eight polymorphic nuclear microsatellites. We employed both population genetics and phylogenetic analyses to clarify the dispersal dynamics and population genetic structure. Results We detected relatively high genetic differentiation between populations (F_ST = ?0.041 to 0.111 for COI, ?0.060 to 0.108 for microsatellites) at both fine and large geographical scales. Bayesian clustering and three‐dimensional factorial correspondence analyses consistently revealed two genetically distinct clusters, highlighting genetic discontinuities in the invaded range. Results of all genetic analyses suggest ship‐mediated ‘jump’ dispersal as the dominant mode of spread of golden mussels in South America, while downstream natural dispersal has had limited effects on contemporary genetic patterns. Main conclusions Our study provides new evidence that post‐establishment dispersal dynamics and genetic patterns vary across geographical scales. While ship‐mediated ‘jump’ dispersal dominates post‐establishment spread of golden mussels in South America, once colonies become established in upstream locations, larvae produced may be advected downstream to infill patchy distributions. Moreover, genetic structuring at fine geographical scales, especially within the same drainages, suggests a further detailed understanding of dynamics of larval dispersal and settlement in different water systems. Knowledge of the mechanisms by which post‐establishment spread occurs can, in some cases, be used to limit dispersal of golden mussels and other introduced species.     

Genetic assessment of the Iberian wolf Canis lupus signatus captive breeding program

The main goal of ex situ conservation programs is to improve the chances of long term survival of natural populations by founding and managing captive colonies that can serve as a source of individuals for future reintroductions or to reinforce existing populations. The degree in which a captive breeding program has captured the genetic diversity existing in the source wild population has seldom been evaluated. In this study we evaluate the genetic diversity in wild and captive populations of the Iberian wolf, Canis lupus signatus, in order to assess how much genetic diversity is being preserved in the ongoing ex situ conservation program for this subspecies. A sample of domestic dogs was also included in the analysis for comparison. Seventy-four wolves and 135 dogs were genotyped at 13 unlinked microsatellite loci. The results show that genetic diversity in Iberian wolves is comparable in magnitude to that of other wild populations of gray wolf. Both the wild and the captive Iberian wolf populations have a similarly high genetic diversity indicating that no substantial loss of diversity has occurred in the captive-breeding program. The effective number of founders of the program was estimated as ∼ ∼16, suggesting that all founders in the studbook pedigree were genetically independent. Our results emphasize also the genetic divergence between wolves and domestic dogs and indicate that our set of 13 microsatellite loci provide a powerful diagnostic test to distinguish wolves, dogs and their hybrids.     

POPULATION VARIATION,OUTCROSSING, AND COLONIZATION OF DISTURBED AREAS BY CALAMAGROSTIS CANADENSIS: EVIDENCE FROM ALLOZYME ANALYSIS

Calamagrostis canadensis (a rhizomatous grass) exists in temperate forest sites of different successional age. It can rapidly colonize disturbed sites to form dense swards. We examined allozyme variation in: four populations (mature forest, intermediate aged forest, forest cutblock, wetland); nine small plots (2 m × 4 m) within the cutblock; and progeny of several families from three populations; in order to assess the mode of colonization of disturbed areas and the effect of successional changes on population genetic structure. All four populations showed equal and extensive genetic variation (1.5 to 1.7 alleles per locus [K], 41.7% to 50% polymorphic loci [PPL], H_st = 0.155 to 0.208) and were not genetically differentiated (G_st = 0.0193, 1 = 0.986 to 0.997). The cutblock subpopulations also showed considerable genetic variation (K = 1.6 to 1.8, PPL = 50% to 58.3%, H_st = 0.151 to 0.278) and no microdifferentiation (G_st = 0.034, I = 0.967 to 0.997). We found 14 different genotypes among the 30 individuals sampled from the cutblock as a whole (based on five polymorphic loci). The cutblock subpopulations had from nine to 14 different genotypes each (same five loci, 18 individuals per subpopulation). Seed produced was primarily outcrossed (multilocus estimate 0.888 to 0.900). We concluded that disturbed sites are colonized primarily by sexually produced seedlings. Potential genetic drift and natural selection, which occur during subsequent successional changes, do not result in reduced genetic variation or population differentiation.     

Historical biogeography of two alpine butterflies in the Rocky Mountains: broad-scale concordance and local-scale discordance

Aim We inferred the phylogeography of the alpine butterfly Colias meadii Edwards (Pieridae) and compared its genetic structure with that of another high elevation, co‐distributed butterfly, Parnassius smintheus Doubleday (Papilionidae), to test if the two Rocky Mountain butterflies responded similarly to the palaeoclimatic cycles of the Quaternary. Location Specimens were collected from 18 alpine sites in the Rocky Mountains of North America, from southern Colorado to northern Montana. Methods We sequenced 867 and 789 nucleotides of cytochrome oxidase I from an average of 19 and 20 individuals for C. meadii and P. smintheus, respectively, from each of the same 18 localities. From the sequence data, we calculated measures of genetic diversity within each population (H, θ), genetic divergence among populations (F_ST), and tested for geographic structure through an analysis of molecular variance (amova ). Population estimates were compared against latitude and between species using a variety of statistical tests. Furthermore, nested clade analysis was implemented to infer historic events underlying the geographic distribution of genetic variation in each species. Then, we compared the number of inferred population events between species using a nonparametric Spearman's rank correlation test. Finally, we ran coalescent simulations on each species’ genealogy to test whether the two species of Lepidoptera fit the same model of population divergence. Results Our analyses revealed that: (1) measures of within‐population diversity were not correlated with latitude for either species, (2) within‐site diversity was not correlated between species, (3) within a species, nearly all populations were genetically isolated, (4) both species exhibited significant and nearly identical partitioning of genetic variation at all hierarchical levels of the amova , including a strong break between populations across the Wyoming Basin, (5) both species experienced similar cycles of expansion and contraction, although fewer were inferred for C. meadii, and (6) data from both species fit a model of three refugia diverging during the Pleistocene. Main conclusions While our findings supported a shared response of the two butterfly species to historic climate change across coarse spatial scales, a common pattern was not evident at finer spatial and temporal scales. The shared demographic history of the two species is consistent with an expanding–contracting archipelago model, suggesting that populations persisted across the geographic range throughout the climate cycles, experiencing isolation on ‘sky islands’ during interglacial periods and becoming connected as they migrated down‐slope during cool, wet climates.     

From the Apennines to the Alps: colonization genetics of the naturally expanding Italian wolf (Canis lupus) population

Wolves in Italy strongly declined in the past and were confined south of the Alps since the turn of the last century, reduced in the 1970s to approximately 100 individuals surviving in two fragmented subpopulations in the central-southern Apennines. The Italian wolves are presently expanding in the Apennines, and started to recolonize the western Alps in Italy, France and Switzerland about 16 years ago. In this study, we used a population genetic approach to elucidate some aspects of the wolf recolonization process. DNA extracted from 3068 tissue and scat samples collected in the Apennines (the source populations) and in the Alps (the colony), were genotyped at 12 microsatellite loci aiming to assess (i) the strength of the bottleneck and founder effects during the onset of colonization; (ii) the rates of gene flow between source and colony; and (iii) the minimum number of colonizers that are needed to explain the genetic variability observed in the colony. We identified a total of 435 distinct wolf genotypes, which showed that wolves in the Alps: (i) have significantly lower genetic diversity (heterozygosity, allelic richness, number of private alleles) than wolves in the Apennines; (ii) are genetically distinct using pairwise F(ST) values, population assignment test and Bayesian clustering; (iii) are not in genetic equilibrium (significant bottleneck test). Spatial autocorrelations are significant among samples separated up to c. 230 km, roughly correspondent to the apparent gap in permanent wolf presence between the Alps and north Apennines. The estimated number of first-generation migrants indicates that migration has been unidirectional and male-biased, from the Apennines to the Alps, and that wolves in southern Italy did not contribute to the Alpine population. These results suggest that: (i) the Alps were colonized by a few long-range migrating wolves originating in the north Apennine subpopulation; (ii) during the colonization process there has been a moderate bottleneck; and (iii) gene flow between sources and colonies was moderate (corresponding to 1.25-2.50 wolves per generation), despite high potential for dispersal. Bottleneck simulations showed that a total of c. 8-16 effective founders are needed to explain the genetic diversity observed in the Alps. Levels of genetic diversity in the expanding Alpine wolf population, and the permanence of genetic structuring, will depend on the future rates of gene flow among distinct wolf subpopulation fragments.     

Contrasting demographic and genetic estimates of dispersal in the endangered Coahuilan box turtle: a contemporary approach to conservation

The evolutionary viability of an endangered species depends upon gene flow among subpopulations and the degree of habitat patch connectivity. Contrasting population connectivity over ecological and evolutionary timescales may provide novel insight into what maintains genetic diversity within threatened species. We employed this integrative approach to evaluating dispersal in the critically endangered Coahuilan box turtle (Terrapene coahuila) that inhabits isolated wetlands in the desert‐spring ecosystem of Cuatro Ciénegas, Mexico. Recent wetland habitat loss has altered the spatial distribution and connectivity of habitat patches; and we therefore predicted that T. coahuila would exhibit limited movement relative to estimates of historic gene flow. To evaluate contemporary dispersal patterns, we employed mark–recapture techniques at both local (wetland complex) and regional (intercomplex) spatial scales. Gene flow estimates were obtained by surveying genetic variation at nine microsatellite loci in seven subpopulations located across the species’ geographical range. The mark–recapture results at the local spatial scale reveal frequent movement among wetlands that was unaffected by interwetland distance. At the regional spatial scale, dispersal events were relatively less frequent between wetland complexes. The complementary analysis of population genetic substructure indicates strong historic gene flow (global F_ST = 0.01). However, a relationship of genetic isolation by distance across the geographical range suggests that dispersal limitation exists at the regional scale. Our approach of contrasting direct and indirect estimates of dispersal at multiple spatial scales in T. coahuila conveys a sustainable evolutionary trajectory of the species pending preservation of threatened wetland habitats and a range‐wide network of corridors.     

Genetic structure of California's elk: a legacy of extirpations,reintroductions, population expansions,and admixture

California, USA, is home to 3 subspecies of North American elk (Cervus canadensis): Roosevelt (C. c. roosevelti), Rocky Mountain (C. c. nelsoni), and tule (C. c. nannodes). Effective management requires a baseline understanding of each subspecies' range, admixture zones, and geographic patterns of genetic diversity. To address these questions, we genotyped 1,271 individual elk from California (n = 1,204) and reference populations of Rocky Mountain and Roosevelt elk from Nevada (n = 32) and Oregon (n = 35), USA. Using 19 polymorphic microsatellite loci, we detected admixture between Roosevelt and Rocky Mountain elk at a contact zone in northern California, and between Roosevelt and tule elk in north-coastal California and central-coastal California. We identified a genetically distinct population of Roosevelt elk in northwestern California, likely reflecting the remnant population that survived a large demographic decline from overhunting during the 1800s. Tule elk exhibited lower levels of heterozygosity (0.44 ± 0.03 [SD]) and allelic richness (2.9 ± 0.2) than Rocky Mountain (0.58 ± 0.05, 4.9 ± 0.4, respectively) and Roosevelt (0.50 ± 0.06, 4.4 ± 0.6, respectively) elk. Among tule elk populations, heterozygosity varied, with the lowest heterozygosity (0.23 ± 0.05) corresponding to the oldest enclosed herd used over the past century as a source of translocations. Among tule elk populations, genetic structure revealed several cases of successful and unsuccessful reintroduction or augmentation attempts. Results provide an essential baseline for future monitoring and decisions about harvest management, translocations to preserve genetic diversity, and landscape-level conservation planning to maintain, enhance, or obstruct connectivity of elk populations. Genome-wide sequencing and analyses are needed to quantify inbreeding absolutely and assess genetic load and the age of admixture where subspecies currently exchange genes.     

Fine-scale genetic structure in Ethiopian wolves imposed by sociality,migration, and population bottlenecks

We used demographic, spatial, and microsatellite data to assess fine-scale genetic structure in Ethiopian wolves found in the Bale Mountains and evaluated the impact of historical versus recent demographic processes on genetic variation. We applied several analytical methods, assuming equilibrium and nonequilibrium conditions, to assess demography and genetic structure. Genetic variation (H _E = 0.584–0.607, allelic richness = 4.2–4.3) was higher than previously reported for this species and genetic structure was influenced by geography and social structure. Statistically significant F _ST values (0.06–0.08) implied differentiation among subpopulations. STRUCTURE analyses showed that neighbouring packs often have shared co-ancestry and spatial autocorrelation showed higher genetic similarity between individuals within packs and between individuals in neighbouring packs compared to random pairs of individuals. Recent effective population sizes were lower than 2n (where n is the number of packs) and lower than the number of breeding individuals with N _e /N ratios near 0.20. All subpopulations have experienced bottlenecks, one occurring due to a rabies outbreak in 2003. Nevertheless, differentiation among these subpopulations is consistent with long-term migration rates and fragmentation at the end of the Pleistocene. Enhanced drift due to population bottlenecks may be countered by higher migration into disease-affected subpopulations. Contemporary factors such as social structure and population bottlenecks are clearly influencing the level and distribution of genetic variation in this population, which has implications for its conservation.     

Rise and fall of a wolf population: genetic diversity and structure during recovery,rapid expansion and drastic decline

The grey wolves (Canis lupus) of Finland have had a varied history, with a period of rapid population expansion after the mid‐1990s followed by a decline with a current census size of about 140 wolves. Here, we investigate the impact of unstable population size and connectivity on genetic diversity and structure in a long‐term genetic study of 298 Finnish wolves born in 1995–2009 and genotyped for 17 microsatellite loci. During the initial recovery and prior to population expansion, genetic diversity was high (1995–1997: LD‐N_e = 67.2; H_o = 0.749; H_e = 0.709) despite a small census size and low number of breeders (N_c < 100; N_b < 10) likely reflecting the status of the Russian source population. Surprisingly, observed heterozygosity decreased significantly during the study period (t = ?2.643, P = 0.021) despite population expansion, likely a result of an increase in inbreeding (F_IS = 0.108 in 2007–2009) owing to a low degree of connectivity with adjacent Russian wolf population (m = 0.016–0.090; F_ST = 0.086, P < 0.001) and population crash after 2006. However, population growth had a temporary positive impact on N_e and number of family lines. This study shows that even strong population growth alone might not be adequate to retain genetic diversity, especially when accompanied with low amount of subsequent gene flow and population decline.