Fine-scale spatial genetic correlation analyses reveal strong female philopatry within a brush-tailed rock-wallaby colony in southeast Queensland

We combine spatial data on home ranges of individuals and microsatellite markers to examine patterns of fine-scale spatial genetic structure and dispersal within a brush-tailed rock-wallaby (Petrogale penicillata) colony at Hurdle Creek Valley, Queensland. Brush-tailed rock-wallabies were once abundant and widespread throughout the rocky terrain of southeastern Australia; however, populations are nearly extinct in the south of their range and in decline elsewhere. We use pairwise relatedness measures and a recent multilocus spatial autocorrelation analysis to test the hypotheses that in this species, within-colony dispersal is male-biased and that female philopatry results in spatial clusters of related females within the colony. We provide clear evidence for strong female philopatry and male-biased dispersal within this rock-wallaby colony. There was a strong, significant negative correlation between pairwise relatedness and geographical distance of individual females along only 800 m of cliff line. Spatial genetic autocorrelation analyses showed significant positive correlation for females in close proximity to each other and revealed a genetic neighbourhood size of only 600 m for females. Our study is the first to report on the fine-scale spatial genetic structure within a rock-wallaby colony and we provide the first robust evidence for strong female philopatry and spatial clustering of related females within this taxon. We discuss the ecological and conservation implications of our findings for rock-wallabies, as well as the importance of fine-scale spatial genetic patterns in studies of dispersal behaviour.     

Habitat connectivity, more than species’ biology, influences genetic differentiation in a habitat specialist, the short-eared rock-wallaby (Petrogale brachyotis)

It is difficult to assess the relative influence of anthropogenic processes (e.g., habitat fragmentation) versus species’ biology on the level of genetic differentiation among populations when species are restricted in their distribution to fragmented habitats. This issue is particularly problematic for Australian rock-wallabies (Petrogale sp.), where most previous studies have examined threatened species in anthropogenically fragmented habitats. The short-eared rock-wallaby (Petrogale brachyotis) provides an opportunity to assess natural population structure and gene flow in relatively continuous habitat across north-western Australia. This region has reported widespread declines in small-to-medium sized mammals, making data regarding the influence of habitat connectivity on genetic diversity important for broad-scale management. Using non-invasive and standard methods, 12 microsatellite loci and mitochondrial DNA were compared to examine patterns of population structure and dispersal among populations of P. brachyotis in the Kimberley, Western Australia. Low genetic differentiation was detected between populations separated by up to 67?km. The inferred genetic connectivity of these populations suggests that in suitable habitat P. brachyotis can potentially disperse far greater distances than previously reported for rock-wallabies in more fragmented habitat. Like other Petrogale species male-biased dispersal was detected. These findings suggest that a complete understanding of population biology may not be achieved solely by the study of fragmented populations in disturbed environments and that management strategies may need to draw on studies of populations (or related species) in undisturbed areas of contiguous habitat.     

Using Genetic Tools to Track Desert Bighorn Sheep Colonizations

ABSTRACT Understanding colonization is vital for managing fragmented populations. We employed mitochondrial DNA haplotypes and 14 microsatellite (nuclear DNA) markers to infer the origins of newly established populations of desert bighorn sheep (Ovis canadensis nelsoni) and to assess loss of genetic diversity during natural colonizations. We used haplotype distribution, F-statistics, Bayesian population clustering, and assignment tests to infer source populations for 3 recent colonies and identified a previously undetected colonization from multiple source populations. Allelic richness declined in 3 of 4 colonies in comparison to the primary source populations, but not as much as has been reported for translocated populations. Heterozygosity declined in only one colony. We also demonstrated that both native and translocated desert bighorn sheep have naturally recolonized empty habitats and suggest that colonization may partially offset population extinction in the region as long as connectivity is maintained. Genetic techniques and mitochondrial DNA haplotypes we described will allow managers to determine the origins of future colonizations by bighorn sheep in California, USA, and prioritize protection of linkages between known sources and colonies.     

An empirical verification of population assignment methods by marking and parentage data: hatchery and wild steelhead (Oncorhynchus mykiss) in Forks Creek, Washington, USA

Assignment tests are increasingly applied in ecology and conservation, although empirical comparisons of methods are still rare or are restricted to few of the available approaches. Furthermore, the performance of assignment tests in cases with low population differentiation, violations of Hardy-Weinberg equilibrium and unbalanced sampling designs has not been verified. The release of adult hatchery steelhead to spawn in Forks Creek in 1996 and 1997 provided an opportunity to compare the power of different assignment methods to distinguish their offspring from those of sympatric wild steelhead. We compared standard assignment methods requiring baseline samples (frequency, distance and Bayesian) and clustering approaches with and without baseline information, using six freely available computer programs. Assignments were verified by parentage data obtained for a subset of returning offspring. All methods provided similar assignment success, despite low differentiation between wild and hatchery fish (F(ST) = 0.02). Bayesian approaches with baseline data performed best, whereas the results of clustering methods were variable and depended on the samples included in the analysis and the availability of baseline information. Removal of a locus with null alleles and equalizing sample sizes had little effect on assignments. Our results demonstrate the robustness of most assignment tests to low differentiation and violations of assumptions, as well as their utility for ecological studies that require correct classification of different groups.     

Individual assignment using microsatellite DNA reveals unambiguous breed identification in the domestic dog

Modern individual clustering methods utilising hypervariable nuclear microsatellite DNA polymorphisms are being increasingly applied in the field of population genetics. This study explores the efficiency of the clustering methods in identifying the breeds of origin of 250 domestic dog (Canis familiaris) individuals based on 10 microsatellite loci. An allele sharing distance (DAS) matrix and the corresponding neighbour-joining tree of individuals revealed monophyletic assemblages that corresponded perfectly with the breeds of origin of the dogs. Individual assignment tests using a Bayesian statistical approach, an allele frequency based method, and a DCE genetic distance based method were all extremely powerful. Most strikingly, the Bayesian method provided 100% assignment success of individuals into their correct breeds of origin and 100% exclusion success of individuals from all alternate reference populations with a high level of statistical confidence (P < 0.0001). A Bayesian Markov Chain Monte Carlo clustering approach revealed clear distinction of individuals into groups according to their breeds of origin, with a near-zero level of 'genetic admixture' among breeds. The results demonstrate that an FST of 0.18, mean expected gene diversity of 0.6 across 10 loci, and approximately 50 individuals per reference population suffice to provide maximum individual assignment success in C. familiaris. This refutes the traditional view that DNA based dog breed identification is not feasible at the individual level of resolution.     

An empirical assessment of individual-based population genetic statistical techniques: application to British pig breeds

Recently developed Bayesian genotypic clustering methods for analysing genetic data offer a powerful tool to evaluate the genetic structure of domestic farm animal breeds. The unit of study with these approaches is the individual instead of the population. We aimed to empirically evaluate various individual-based population genetic statistical methods for characterization of genetic diversity and structure of livestock breeds. Eighteen British pig populations, comprising 819 individuals, were genotyped at 46 microsatellite markers. Three Bayesian genotypic clustering approaches, principle component analysis (PCA) and phylogenetic reconstruction were applied to individual multilocus genotypes to infer the genetic structure and diversity of the British pig breeds. Comparisons of the three Bayesian genotypic clustering methods (, and ) revealed some broad similarities but also some notable differences. Overall, the methods agreed that majority of the British pig breeds are independent genetic units with little evidence of admixture. The three Bayesian genotypic clustering methods provided complementary, biologically credible clustering solutions but at different levels of resolution. detected finer genetic differentiation and in some cases, populations within breeds. Consequently, it estimated a greater number of underlying genetic populations (K, in the notation of Bayesian clustering methods). Two of the Bayesian methods ( and ) and phylogenetic reconstruction provided similar success in assignment of individuals, supporting the use of these methods for breed assignment.     

Genetic footprints reveal geographic patterns of expansion in Fennoscandian red foxes

Population expansions of boreal species are among the most substantial ecological consequences of climate change, potentially transforming both structure and processes of northern ecosystems. Despite their importance, little is known about expansion dynamics of boreal species. Red foxes (Vulpes vulpes) are forecasted to become a keystone species in northern Europe, a process stemming from population expansions that began in the 19th century. To identify the relative roles of geographic and demographic factors and the sources of northern European red fox population expansion, we genotyped 21 microsatellite loci in modern and historical (1835–1941) Fennoscandian red foxes. Using Bayesian clustering and Bayesian inference of migration rates, we identified high connectivity and asymmetric migration rates across the region, consistent with source‐sink dynamics, whereby more recently colonized sampling regions received immigrants from multiple sources. There were no clear clines in allele frequency or genetic diversity as would be expected from a unidirectional range expansion from south to north. Instead, migration inferences, demographic models and comparison to historical red fox genotypes suggested that the population expansion of the red fox is a consequence of dispersal from multiple sources, as well as in situ demographic growth. Together, these findings provide a rare glimpse into the anatomy of a boreal range expansion and enable informed predictions about future changes in boreal communities.     

Population structure of the yellow-footed rock-wallaby Petrogale xanthopus (Gray, 1854) inferred from mtDNA sequences and microsatellite loci

The yellow-footed rock-wallaby Petrogale xanthopus is considered to be potentially vulnerable to extinction. This wallaby inhabits naturally disjunct rocky outcrops which could restrict dispersal between populations, but the extent to which that occurs is unknown. Genetic differences between populations were assessed using mitochondrial DNA (control region) sequencing and analysis of variation at four microsatellite loci among three geographically close sites in south-west Queensland (P. x. celeris) and, for mtDNA only, samples from South Australia (P. x. xanthopus) as well. Populations from South Australia and Queensland had phylogenetically distinct mtDNA, supporting the present classification of these two groups as evolutionarily distinct entities. Within Queensland, populations separated by 70 km of unsuitable habitat differed significantly for mtDNA and at microsatellite loci. Populations separated by 10 km of apparently suitable habitat had statistically homogeneous mtDNA, but a significant difference in allele frequency at one microsatellite locus. Tests for Hardy-Weinberg equilibrium and micro-geographical variation at microsatellite loci did not detect any substructuring between two wallaby aggregations within a colony encircling a single rock outcrop. Although the present study was limited by small sample sizes at two of the three Queensland locations examined, the genetic results suggest that dispersal between colonies is limited, consistent with an ecological study of dispersal at one of the sites. Considering both the genetic and ecological data, we suggest that management of yellow-footed rock-wallabies should treat each colony as an independent unit and that conservation of the Queensland and South Australian populations as separate entities is warranted.     

Fine-scale spatial genetic structure and dispersal among spotted salamander (Ambystoma maculatum) breeding populations

We examined fine-scale genetic variation among breeding aggregations of the spotted salamander (Ambystoma maculatum) to quantify dispersal, interpopulation connectivity and population genetic structure. Spotted salamanders rely on temporary ponds or wetlands for aggregate breeding. Adequate breeding sites are relatively isolated from one another and field studies suggest considerable adult site fidelity; therefore, we expected to find population structure and differentiation at small spatial scales. We used microsatellites to estimate population structure and dispersal among 29 breeding aggregations in Tompkins County, New York, USA, an area encompassing 1272 km(2). Bayesian and frequency-based analyses revealed fine-scale genetic structure with two genetically defined demes: the North deme included seven breeding ponds, and the South deme included 13 ponds. Nine ponds showed evidence of admixture between these two genetic pools. Bayesian assignment tests for detection of interpopulation dispersal indicate that immigration among ponds is common within demes, and that certain populations serve as sources of immigrants to neighbouring ponds. Likewise, spatial genetic correlation analyses showed that populations < or = 4.8 km distant from each other show significant genetic correlation that is not evident at higher scales. Within-population levels of relatedness are consistently larger than expected if mating were completely random across ponds, and in the case of a few ponds, within-population processes such as inbreeding or reproductive skew contribute significantly to differentiation from neighbouring ponds. Our data underscore the importance of these within-population processes as a source of genetic diversity across the landscape, despite considerable population connectivity. Our data further suggest that spotted salamander breeding groups behave as metapopulations, with population clusters as functional units, but sufficient migration among demes to allow for potential rescue and recolonization. Amphibian habitats are becoming increasingly fragmented and a clear understanding of dispersal and patterns of population connectivity for taxa with different ecologies and life histories is crucial for their conservation.     

Longer holding times decrease dispersal but increase mortality of translocated scaled quail

Scaled quail (Callipepla squamata) decline caused by habitat loss and fragmentation increased interest in translocation to reestablish populations. Yet factors determining translocation success are poorly understood. We tested hypotheses concerning the influence of source population and variation in delayed release strategy (1–9 weeks) on mortality and dispersal of wild-caught, translocated scaled quail. We trapped and translocated quail from 2016–2017 from source populations in the Edwards Plateau and Rolling Plains ecoregions to a large contiguous (>40,000 ha) release site in Knox County, Texas, USA. We evaluated mortality and dispersal of translocated females as a function of source population, holding time prior to release, age, release location, and year using a multi-state mark-recapture model with state uncertainty. Scaled quail translocated within the Rolling Plains were more likely to exhibit philopatry to the release site. Quail with longer holding times had higher mortality but lower dispersal rates. The Edwards Plateau is a suitable source site for translocation in the Rolling Plains. The reduced dispersal but higher mortality of translocated scaled quail associated with longer holding times creates a decision tradeoff for managers.     

Genetic admixture between captive-bred and wild individuals affects patterns of dispersal in a brown trout (<Emphasis Type="Italic">Salmo trutta</Emphasis>) population

Genetic admixture between captive-bred and wild individuals has been demonstrated to affect many individual traits, although little is known about its potential influence on dispersal, an important trait governing the eco-evolutionary dynamics of populations. Here, we quantified and described the spatial distribution of genetic admixture in a brown trout (Salmo trutta) population from a small watershed that was stocked until 1999, and then tested whether or not individual dispersal parameters were related to admixture between wild and captive-bred fish. We genotyped 715 fish at 17 microsatellite loci sampled from both the mainstream and all populated tributaries, as well as 48 fish from the hatchery used to stock the study area. First, we used Bayesian clustering to infer local genetic structure and to quantify genetic admixture. We inferred first generation migrants to identify dispersal events and test which features (genetic admixture, sex and body length) affected dispersal parameters (i.e. probability to disperse, distance of dispersal and direction of the dispersal event). We identified two genetic clusters in the river basin, corresponding to wild fish on the one hand and to fish derived from the captive strain on the other hand, allowing us to define an individual gradient of admixture. Individuals with a strong assignment to the captive strain occurred almost exclusively in some tributaries, and were more likely to disperse towards a tributary than towards a site of the mainstream. Furthermore, dispersal probability increased as the probability of assignment to the captive strain increased, and individuals with an intermediate level of admixture exhibited the lowest dispersal distances. These findings show that various dispersal parameters may be biased by admixture with captive-bred genotypes, and that management policies should take into account the differential spread of captive-bred individuals in wild populations.     

Genetic diversity and population structure of Tasmanian devils, the largest marsupial carnivore

Genetic diversity and population structure were investigated across the core range of Tasmanian devils (Sarcophilus laniarius; Dasyuridae), a wide-ranging marsupial carnivore restricted to the island of Tasmania. Heterozygosity (0.386-0.467) and allelic diversity (2.7-3.3) were low in all subpopulations and allelic size ranges were small and almost continuous, consistent with a founder effect. Island effects and repeated periods of low population density may also have contributed to the low variation. Within continuous habitat, gene flow appears extensive up to 50 km (high assignment rates to source or close neighbour populations; nonsignificant values of pairwise FST), in agreement with movement data. At larger scales (150-250 km), gene flow is reduced (significant pairwise FST) but there is no evidence for isolation by distance. The most substantial genetic structuring was observed for comparisons spanning unsuitable habitat, implying limited dispersal of devils between the well-connected, eastern populations and a smaller northwestern population. The genetic distinctiveness of the northwestern population was reflected in all analyses: unique alleles; multivariate analyses of gene frequency (multidimensional scaling, minimum spanning tree, nearest neighbour); high self-assignment (95%); two distinct populations for Tasmania were detected in isolation by distance and in Bayesian model-based clustering analyses. Marsupial carnivores appear to have stronger population subdivisions than their placental counterparts.     

Can assignment tests measure dispersal?

Individual-based assignment tests are now standard tools in molecular ecology and have several applications, including the study of dispersal. The measurement of natal dispersal is vital to understanding the ecology of many species, yet the accuracy of assignment tests in situations where natal dispersal is common remains untested in the field. We studied a metapopulation of the grand skink, Oligosoma grande, a large territorial lizard from southern New Zealand. Skink populations occur on isolated, regularly spaced rock outcrops and are characterized by frequent interpopulation dispersal. We examined the accuracy of assignment tests at four replicate sites by comparing long-term mark-and-recapture records of natal dispersal with the results of assignment tests based on microsatellite DNA data. Assignment tests correctly identified the natal population of most individuals (65-100%, depending on the method of assignment), even when interpopulation dispersal was common (5-20% dispersers). They also provided similar estimates of the proportions of skinks dispersing to those estimated by the long-term mark-and-recapture data. Fully and partially Bayesian assignment methods were equally accurate but their accuracy depended on the stringency applied, the degree of genetic differentiation between populations, and the number of loci used. In addition, when assignments required high confidence, the method of assignment (fully or partially Bayesian) had a large bearing on the number of individuals that could be assigned. Because assignment tests require significantly less fieldwork than traditional mark-and-recapture approaches (in this study < 3 months vs. > 7 years), they will provide useful dispersal data in many applied and theoretical situations.     

The influence of multiple dispersal mechanisms and landscape structure on population clustering and connectivity in fragmented artesian spring snail populations

Many organisms occupy heterogeneous landscapes that contain both barriers to movement as well as corridors that facilitate dispersal. The extent to which such features determine population connectivity will depend on the mechanisms utilized by organisms to disperse. Here we examined the interaction between landscape structure and dispersal in the endemic aquatic snail, Fonscochlea accepta , in the fragmented artesian spring ecosystem of arid central Australia. We used frequentist and Bayesian analyses of microsatellite data to identify population structure and immigration for 1130 snails sampled from 50 springs across an entire spring complex. We introduce a modified isolation-by-distance analysis to test hypotheses about how populations are clustered and to distinguish the most likely dispersal pathways within and between those clusters. Highly significant differences in F _ST values and significant isolation-by-distance patterns were detected among springs across the entire complex, while Bayesian assignment tests revealed the presence of two hierarchical levels of spring clustering. Clusters were defined by the spatial aggregation of springs, dynamic aquatic habitat connections between springs and the ecology of the snails. Bayesian immigrant identification and our modified isolation-by-distance analysis revealed that dispersal occurs at two geographical scales via two very different mechanisms. Short range dispersal (usually ≤ 300 m) occurs via active movement facilitated by aquatic connections among springs while long-range dispersal (≥ 3 km) is likely facilitated by an animal vector (phoresy). These results underline the importance of both dispersal mode and landscape structure in influencing connectivity rates and patterns among populations.     

A simulation-based evaluation of methods for inferring linear barriers to gene flow

Different analytical techniques used on the same data set may lead to different conclusions about the existence and strength of genetic structure. Therefore, reliable interpretation of the results from different methods depends on the efficacy and reliability of different statistical methods. In this paper, we evaluated the performance of multiple analytical methods to detect the presence of a linear barrier dividing populations. We were specifically interested in determining if simulation conditions, such as dispersal ability and genetic equilibrium, affect the power of different analytical methods for detecting barriers. We evaluated two boundary detection methods (Monmonier's algorithm and WOMBLING), two spatial Bayesian clustering methods (TESS and GENELAND), an aspatial clustering approach (STRUCTURE), and two recently developed, non-Bayesian clustering methods [PSMIX and discriminant analysis of principal components (DAPC)]. We found that clustering methods had higher success rates than boundary detection methods and also detected the barrier more quickly. All methods detected the barrier more quickly when dispersal was long distance in comparison to short-distance dispersal scenarios. Bayesian clustering methods performed best overall, both in terms of highest success rates and lowest time to barrier detection, with GENELAND showing the highest power. None of the methods suggested a continuous linear barrier when the data were generated under an isolation-by-distance (IBD) model. However, the clustering methods had higher potential for leading to incorrect barrier inferences under IBD unless strict criteria for successful barrier detection were implemented. Based on our findings and those of previous simulation studies, we discuss the utility of different methods for detecting linear barriers to gene flow.     

Hematology and serum biochemistry of the brush-tailed rock-wallaby (Petrogale penicillata)

In Australia the brush-tailed rock-wallaby (Petrogale penicillata) is the subject of a national recovery plan, and several sites have been selected for reintroductions. Condition of wild populations and individual animals can be monitored using hematologic and serum biochemistry analytes, and hematologic variables have been correlated with postrelease survival in other species. Prior to such monitoring, reference values for blood variables are required, but these data have not been available for the brush-tailed rock-wallaby. During four trapping periods from November 2004 to August 2005, 116 blood samples were collected from 44 brush-tailed rock-wallabies in a wild colony in southeast Queensland. Some variables varied with sex, age, method of restraint, lactation demands, and trapping period. After partitioning, when required, reference ranges for hematology and serum biochemistry variables were established. This study provides the most comprehensive serum biochemistry reference range for any macropodid marsupial yet published.     

Dispersal and population genetic structure of Telmatherina antoniae,an endemic freshwater Sailfin silverside from Sulawesi,Indonesia

Population genetic structure in the presence of substantial dispersal provides a unique perspective on the evolution of reproductive isolation. We sampled Telmatherina antoniae, an endemic fish species, at 10 sites in Lake Matano, Indonesia. Significant genetic structure (F_ST = 0.03) was found, despite a migration rate of 10.2% and a mean dispersal distance of 13.6 km, estimated by genotype assignment. Neither dispersal distance nor direction differed from random expectations, indicative of no dispersal barrier in Lake Matano. However, Bayesian genotype cluster assignment identified a population structure consisting of four to six clusters that did not coincide with sample site distribution, but explained two to three times more genetic variance than sample site. The mechanism for continued isolation of those genetic clusters is unknown, but assortative mating and temporal isolation are obvious candidates. Our results resolve the apparent paradox of population genetic structure coupled with frequent dispersal, and highlight the importance of considering cryptic genetic structure.     

Population structure in Pseudoroegneria spicata (Poaceae: Triticeae) modeled by Bayesian clustering of AFLP genotypes

Pseudoroegneria spicata (Poaceae: Triticeae) is an abundant, allogamous species widely adapted to the temperate, semiarid steppe and open woodland regions of western North America. Amplified fragment length polymorphism (AFLP), model-based Bayesian clustering, and other methods of hypothesis testing were used to investigate genetic diversity and population structure among 565 P. spicata plants from 82 localities representing much of the species distribution. Comparisons with four Asiatic Pseudoroegneria species and two North American Elymus wawawaiensis accessions demonstrate cohesiveness in P. spicata. However, P. spicata genotypes group by locality and geographic region based on genetic distance analysis. Average DNA polymorphism among P. spicata localities was significantly correlated (r = 0.58) with geographical distance. The optimum Bayesian cluster model included 21 P. spicata groups, indicating that dispersal among sampling locations was not sufficient to group genotypes into one unstructured population. Approximately 18.3% of the DNA polymorphism was partitioned among the 21 regional groups, 14.9% among localities within groups, and 66.8% within accessions. Average DNA polymorphism among Bayesian groups was correlated (r = 0.53) with the average geographic distance among Bayesian groups, which partly reflects isolation by distance. However, conspicuous regional boundaries were discernable among several divergent genetic groups.     

Highly asymmetric fine-scale genetic structure between sexes of African striped mice and indication for condition dependent alternative male dispersal tactics

Sex-biased dispersal is observed in many taxa, but few studies have compared sex-biased dispersal among and within populations. We addressed the magnitude and habitat dependency of sex-biased dispersal in social African striped mice by separating group-related from population-related genetic variance to understand the contribution of each sex to deme structure. As dispersal over unoccupied habitat is likely to be more costly than dispersal within a population, we predicted that individuals leaving the natal population have a lower body condition, being inferior to heavier territorial individuals. Fine-scale genetic structure was detected in both sexes. Female relatedness decreased continuously from R = 0.21 at 25 m to zero at 500 m. Maximum male relatedness R = 0.05 was constant at distances between 25 and 75 m, becoming zero at 100 m. Genetic variance (F(ST) ) among seven locations was significantly higher in females than in males, while inbreeding estimates (F(IS) ) were significantly higher in males than in females. Assignment tests estimated significantly more migrants among males, while Bayesian clustering estimated only a single genetic unit cluster for males among the seven locations. The mean body mass of migrant males (44 g) was significantly lower than for males that remained resident and thus dispersed within their sub-population (48 g). Combined, the results showed habitat-independent male-biased dispersal and high female philopatry, and suggested that body condition was more important than kinship in male dispersal decisions. We suggest that locally inferior males are important for gene flow between sub-populations. Thus, males might follow alternative dispersal tactics.     

Population structure of brush-tailed rock-wallaby (Petrogale penicillata) colonies inferred from analysis of faecal DNA

Genetic data obtained using faecal DNA were used to elucidate the population structure of four brush-tailed rock-wallaby (Petrogale penicillata) colonies located in Wollemi National Park, New South Wales. The results suggested that the four sampled colonies are genetically differentiated and do not form a panmictic unit. Based on assignment tests, approximately 5% of sampled individuals were inferred to be dispersers and both male and female migrants were detected. Multilocus spatial autocorrelation analyses provided evidence for increased philopatry among females compared to males within the largest colony in the valley. Females in close spatial proximity were more genetically similar than expected under a random distribution of females, and females separated by more than 400 m were less genetically similar than expected. In contrast, there was no evidence of a significant clustering of related males. This suggests that within-colony dispersal is male biased. We also investigated the best strategies for conserving genetic diversity in this population. All of the four sampled colonies were found to contain distinct components of the genetic diversity of the Wolgan Valley P. penicillata population and loss of any colony is likely to result in the loss of unique alleles. Conservation and management plans should take into account that these colonies represent genetically differentiated discrete subpopulations. This approach is also the best strategy for maintaining the genetic diversity of the populations in this valley.