A genomic perspective on the conservation status of the endangered Nashville crayfish (Faxonius shoupi)

The Nashville crayfish (Faxonius shoupi, Hobbs 1948) was federally listed as an endangered species in 1986 due to its limited distribution in the Mill Creek watershed; this waterway lies in the rapidly developing Nashville basin and has experienced habitat degradation due to agricultural run-off, contamination, and urban development. Recovery efforts, including dam removal and restoration of riparian zones, have improved conditions in Mill Creek and F. shoupi has increased in numbers and recolonized extirpated stream segments. However, a history of demographic bottlenecks and restricted gene flow may have negatively impacted the long-term recovery of this species. A recently discovered population of F. shoupi in a disjunct segment of the Lower Tennessee River at the Pickwick Tailwater may provide an additional source of genetic variation. Uncertainty surrounding the origins of the Pickwick population and its taxonomic relationship to F. shoupi in Mill Creek raises questions about the conservation and management implications of this population. We used mitochondrial sequencing and SNP genotyping to assess genetic variation and connectivity of F. shoupi in the Mill Creek drainage and to investigate the taxonomy and demographic history of the newly discovered population at Pickwick. We found substantial genetic variation and evidence of connectivity for samples throughout Mill Creek for both mitochondrial and genome-wide SNPs. Our results also suggest a recently severed connection between crayfish in Pickwick and Mill Creek. Unique mitochondrial haplotypes and SNP variation in the Pickwick population highlight the need for prioritizing this population in future conservation and management plans for this species.

     

Spatial patterns of genetic structure among populations of a stone‐cased caddis (Trichoptera: Tasimiidae) in south‐east Queensland,Australia

1. Gene flow and dispersal among populations of a stone‐cased caddis (Tasimiidae: Tasimia palpata) were estimated indirectly using a 460 bp region of the cytochrome oxidase I gene of mitochondrial DNA. 2. There was no significant differentiation at the largest spatial scale (between catchments) and no correlation between genetic distance and geographic distance. These results are consistent with widespread adult dispersal. 3. Conversely, significant genetic differentiation was detected at the smallest spatial scale examined (among reaches within streams). This pattern was primarily because of significant F_ST values in a single stream (Bundaroo Creek). 4. Bundaroo Creek also had the lowest mean number of haplotypes per population (n = 7) suggesting that a limited number of females may be responsible for recruitment at these sites. Significant F_ST's at the reach scale may be a result of this ‘patchy’ recruitment. However, additional evidence regarding the long‐range dispersal ability and fecundity of T. palpata females is needed to test this hypothesis fully.     

Genetic signatures of translocations and habitat fragmentation for two evolutionarily significant units of a protected fish species

Genetic population structure was evaluated for the White Sands pupfish (Cyprinodon tularosa), a protected fish species comprised of two Evolutionarily Significant Units (ESUs); the Malpais Spring ESU and the Salt Creek ESU. The Malpais Spring ESU is restricted to Malpais Spring, whereas the Salt Creek ESU includes the native Salt Creek population and two Salt Creek-derived populations at Mound Spring and Lost River; all three of these habitats are physically fragmented. We sampled the upper and lower reaches of the four populations, examining 13 DNA microsatellite loci from 40 individuals per population. As expected, significant genetic structure was observed between the two ESUs; Malpais Spring and Salt Creek. Substantial genetic drift was observed for the introduced Lost River population, with modest genetic drift for the introduced Mound Spring population. Taken together with ecological data, neither of the introduced populations successfully replicates the Salt Creek population. We also report significant reductions in genetic diversity for the upper reaches of both Salt Creek and Lost River, indicating that recent habitat changes have altered the genetic structure of these two populations. We consider these findings along with previously reported ecological data to develop guidelines for managing C. tularosa.     

Extreme population differentiation in a vulnerable slavemaking ant with a fragmented distribution

Understanding levels of population differentiation and inbreeding are important issues in conservation biology, especially for social Hymenoptera with fragmented and small population sizes. Isolated populations are more vulnerable to genetic loss and extinction than those with extended continuous distributions. However, small populations are not always a consequence of a recent reduction of their habitat. Thus, determining the history of population isolation and current patterns of genetic variation of a species is crucial for its conservation. Rossomyrmex minuchae is a slave-making ant with patchy distribution in South Eastern Spain and is classified as vulnerable by the IUCN. In contrast, the other three known species of the genus are presumed to show more uniform distributions. Here we investigate the genetic diversity and population structure of R. minuchae and compare it with that found in two other species of the genus: R. anatolicus and R. quandratinodum. We conclude that although genetic diversity of R. minuchae is low, there is no evidence of a recent bottleneck, suggesting a gradual and natural fragmentation process. We also show extreme population differentiation at nuclear and mitochondrial markers, and isolation by distance at a local scale. Despite some evidence for inbreeding and low genetic variation within populations, we found almost no diploid males, a finding which contrasts with that expected in inbred Hymenoptera with single locus complementary sex determination. This could mean that sex is determined by another mechanism. We argue that continued low population size means that detrimental effects of inbreeding and low genetic variation are likely in the future. We suggest that a policy of artificial gene flow aimed at increasing within population variation is considered as a management option.     

Restricted gene flow between resident Oncorhynchus mykiss and an admixed population of anadromous steelhead

The species Oncorhynchus mykiss is characterized by a complex life history that presents a significant challenge for population monitoring and conservation management. Many factors contribute to genetic variation in O. mykiss populations, including sympatry among migratory phenotypes, habitat heterogeneity, hatchery introgression, and immigration (stray) rates. The relative influences of these and other factors are contingent on characteristics of the local environment. The Rock Creek subbasin in the middle Columbia River has no history of hatchery supplementation and no dams or artificial barriers. Limited intervention and minimal management have led to a dearth of information regarding the genetic distinctiveness of the extant O. mykiss population in Rock Creek and its tributaries. We used 192 SNP markers and collections sampled over a 5‐year period to evaluate the temporal and spatial genetic structures of O. mykiss between upper and lower watersheds of the Rock Creek subbasin. We investigated potential limits to gene flow within the lower watershed where the stream is fragmented by seasonally dry stretches of streambed, and between upper and lower watershed regions. We found minor genetic differentiation within the lower watershed occupied by anadromous steelhead (F_ST = 0.004), and evidence that immigrant influences were prevalent and ubiquitous. Populations in the upper watershed above partial natural barriers were highly distinct (F_ST = 0.093) and minimally impacted by apparent introgression. Genetic structure between watersheds paralleled differences in local demographics (e.g., variation in size), migratory restrictions, and habitat discontinuity. The evidence of restricted gene flow between putative remnant resident populations in the upper watershed and the admixed anadromous population in the lower watershed has implications for local steelhead productivity and regional conservation.     

Genetic integrity and individual identification-based population size estimate of the endangered long-tailed goral,Naemorhedus caudatus from Seoraksan National Park in South Korea,based on a non-invasive genetic approach

ABSTRACT

The long-tailed goral (also called the Amur goral) Naemorhedus caudatus (subfamily Caprinae), a vulnerable and protected species designated by IUCN and CITES, has sharply been declining in the population size and is now becoming critically endangered in South Korea. This species has been conserved as a natural monument by the Korean Cultural Heritage Administration since 1968. In this study, using 78 fecal DNA samples with a non-invasive genetic approach, we assessed the genetic integrity and individual identification-based population size for the goral population from Seoraksan National Park representing the largest wild population in Korea. Using the successfully isolated 38 fecal DNA, phylogeographic and population genetic analyses were performed with mitochondrial DNA control region (CR) sequences and nine microsatellite loci. We found seven CR haplotypes, of which five were unique to the Seoraksan population, considering previously determined haplotypes in Korean populations. The Seoraksan population showed higher haplotype diversity (0.777?±?0.062) and mean number of alleles (4.67?±?1.563) relative to southern populations in Korea reported from previous studies, with no signal of a population bottleneck. Microsatellite-based individual identification estimate based on probability of identity (PID) indicated a population size of ≥30 in this population. Altogether, we suggest that for future management efforts of this species in the Seoraksan National Park, conserving its genetic integrity as an ‘endemic’ lineage, and curbing a decrease in its number through mitigating habitat destruction might be key to secure the population for the long term.     

Mitonuclear mismatch alters performance and reproductive success in naturally introgressed populations of a montane leaf beetle*

Coordination between nuclear and mitochondrial genomes is critical to metabolic processes underlying animals' ability to adapt to local environments, yet consequences of mitonuclear interactions have rarely been investigated in populations where individuals with divergent mitochondrial and nuclear genomes naturally interbreed. Genetic variation in the leaf beetle Chrysomela aeneicollis was assessed along a latitudinal thermal gradient in California's Sierra Nevada. Variation at mitochondrial cytochrome oxidase II (COII) and the nuclear gene phosphoglucose isomerase (PGI) shows concordance and was significantly greater along a 65 km transect than 10 other loci. STRUCTURE analyses using neutral loci identified a southern and northern subpopulation, which interbreed in the central drainage Bishop Creek. COII and PGI were used as indicators of mitochondrial and nuclear genetic variation in field and laboratory experiments conducted on beetles from this admixed population. Fecundity, larval development rate, running speed and male mating frequency were higher for beetles with geographically “matched” than “mismatched” mitonuclear genotypes. Effects of mitonuclear mismatch were largest for individuals with northern nuclear genotypes possessing southern mitochondria and were most pronounced after heat treatment or at high elevation. These findings suggest that mitonuclear incompatibility diminishes performance and reproductive success in nature, effects that could intensify at environmental extremes.     

Evolution of rough sculpin (<Emphasis Type="Italic">Cottus asperrimus</Emphasis>) genetic divergence and late Quaternary displacement on the Hat Creek fault,California, USA

The rough sculpin (Cottus asperrimus) is a threatened species whose geographic range in northwestern California, USA is disrupted by Hat Creek fault. We tested whether the fluvial barriers (rapids and waterfalls) produced by this fault have generated significant phylogeographic structure among rough sculpin populations by analyzing variation in microsatellites and mitochondrial DNA. Rough sculpin isolated on either side of Hat Creek fault exhibited significant genetic divergence (microsatellite F _ST = 0.36; mitochondrial uncorrected p distance = 1 %). Independently derived estimates for the date of divergence, based upon a molecular clock and upon the age of slip on the Hat Creek fault are concordant and indicate divergence was initiated about 0.5–1 million years ago. Based upon the findings of our genetic analysis and the Pleistocene geologic history of midsections of the Pit River, we present a model of evolution of rough sculpin genetic divergence and late Quaternary displacement on Hat Creek fault. Our findings reveal that rough sculpin exhibit significant population structure and that two management units should be recognized within the species for future conservation planning.     

Population Structure of the Giant Garter Snake, Thamnophis gigas

The giant garter snake, Thamnophis gigas, is a threatened species endemic to California’s Central Valley. We tested the hypothesis that current watershed boundaries have caused genetic differentiation among populations of T. gigas. We sampled 14 populations throughout the current geographic range of T. gigas and amplified 859 bp from the mitochondrial gene ND4 and one nuclear microsatellite locus. DNA sequence variation from the mitochondrial gene indicates there is some genetic structuring of the populations, with high F_ST values and unique haplotypes occurring at high frequency in several populations. We found that clustering populations by watershed boundary results in significant between-region genetic variance for mtDNA. However, analysis of allele frequencies at the microsatellite locus NSU3 reveals very low F_ST values and little between-region variation in allele frequencies. The discordance found between mitochondrial and microsatellite data may be explained by aspects of molecular evolution and/or T. gigas life history characteristics. Differences in effective population size between mitochondrial and nuclear DNA, or male-biased gene flow, result in a lower migration rate of mitochondrial haplotypes relative to nuclear alleles. However, we cannot exclude homoplasy as one explanation for homogeneity found for the single microsatellite locus. The mitochondrial nucleotide sequence data supports conservation practices that identify separate management units for T. gigas.     

Mitochondrial introgressive hybridization following a demographic expansion in the tomato frogs of Madagascar,genus Dyscophus

Madagascar is a biodiversity hotspot with a unique fauna and flora largely endemic at the species level and highly threatened by habitat destruction. The processes underlying population‐level differentiation in Madagascar's biota are poorly understood and have been proposed to be related to Pleistocene climatic cycles, yet the levels of genetic divergence observed are often suggestive of ancient events. We combined molecular markers of different variability to assess the phylogeography of Madagascar's emblematic tomato frogs (Dyscophus guineti and D. antongilii) and interpret the observed pattern as resulting from ancient and recent processes. Our results suggest that the initial divergence between these taxa is probably old as reflected by protein‐coding nuclear genes and by a strong mitochondrial differentiation of the southernmost population. Dramatic changes in their demography appear to have been triggered by the end of the last glacial period and possibly by the short return of glacial conditions known as the 8K event. This dramatic change resulted in an approximately 50‐fold reduction of the effective population size in various populations of both species. We hypothesize these species' current mitochondrial DNA diversity distribution reflects a swamping of the mitochondrial genetic diversity of D. guineti by that of D. antongilii previous to the populations' bottlenecks during the Holocene, and probably as a consequence of D. antongilii demographic expansion approximately 1 million years ago. Our data support the continued recognition of D. antongilii and D. guineti as separate species and flag D. guineti as the more vulnerable species to past and probably also future environmental changes.     

Pleistocene origin and population history of a neoendemic alpine butterfly

Alpine environments underwent dramatic transformation during glacial–interglacial cycles, with the consequence that geographical, ecological and demographic changes of alpine populations provided the opportunity for formation of neoendemic species. Several biogeographical models have been proposed to account for the unique history of alpine populations, with different expectations of genetic divergence and speciation. The expanding alpine archipelago model proposes that alpine populations expand spatially and demographically during glacial events, dispersing between mountain ranges. Under this model, alpine populations are unlikely to diverge in isolation due to substantial interpopulation gene flow. In contrast, the alpine archipelago refuge model proposes that gene flow during glacial phases is limited and populations expand demographically during interglacial phases, increasing genetic isolation and the likelihood of speciation. We assess these models by reconstructing the evolutionary history of Colias behrii, a morphologically and ecologically distinct alpine butterfly restricted to the California Sierra Nevada. C. behrii exhibits very low genetic diversity at mitochondrial and nuclear loci, limited population structure and evidence of population expansion. C. behrii and Rocky Mountain C. meadii share identical mitochondrial haplotypes, while in contrast, nuclear data indicate common ancestry between C. behrii and Cascades Range Colias pelidne. The conflict in gene genealogies may be a result of recent expansion in North American Colias, but an isolation with migration analysis indicates that genetic patterns in C. behrii might result from differential introgression following hybridization. Based on the timing of population expansion and gene flow between mountain ranges, the expanding alpine archipelago model is supported in C. behrii.     

Variation in genetic structure among populations of the caddisfly Helicopsyche borealis from three streams in northern California, U.S.A.

1. Allozyme electrophoresis was used to describe the genetic structure of Helicopsyche borealis caddisflies collected from three sites in each of three streams in northern California, U.S.A.: the Rice Fork of the Eel River; Big Sulphur Creek; and Alameda Creek. Between 7 and 11km separated adjacent sites within these three streams. Helicopsyche borealis from three additional streams in eastern North America (Christiana Creek, Indiana; Byrd's Mill Creek, Oklahoma; Susquehanna River, Pennsylvania) were also analysed electrophoretically to address taxonomic questions that arose during the study. 2. Four genetically distinct groups of individuals were identified (i.e. Helicopsyche types A, B, C, and D). Lack of interbreeding between sympatric groups (as evidenced by fixed allelic differences) and large genetic differences (mean Nei's genetic distances = 0.396–0.693) indicate that these four groups of Helicopsyche were actually reproductively isolated species rather than genetic variants of a single species. 3. Occurrence of Helicopsyche type A at multiple sites permitted an analysis of spatial variation in genetic structure. Within a drainage basin, small differences in allele frequencies were observed among sites in the Rice Fork and Big Sulphur Creek, but not in Alameda Creek. Larger genetic differences were found among sites in separate drainage basins. Genetic distances (Nei's) between Helicopsyche type A from California and from eastern North America sites (mean = 0.236) were greater than interpopulation differences commonly observed for insects, which suggests that Helicopsyche type A from California may represent a different species than Helicopsyche type A from eastern North America. 4. Geographical and taxonomic differences observed in this study underscore the importance of understanding both population structure and genetic relationships among populations in the design and interpretation of stream faunal studies.     

Divergence with gene flow in a population of thermophilic bacteria: a potential role for spatially varying selection

A fundamental goal of evolutionary biology is to understand how ecological diversity arises and is maintained in natural populations. We have investigated the contributions of gene flow and divergent selection to the distribution of genetic variation in an ecologically differentiated population of a thermophilic cyanobacterium (Mastigocladus laminosus) found along the temperature gradient of a nitrogen‐limited stream in Yellowstone National Park. For most loci sampled, gene flow appears to be sufficient to prevent substantial genetic divergence. However, one locus (rfbC) exhibited a comparatively low migration rate as well as other signatures expected for a gene experiencing spatially varying selection, including an excess of common variants, an elevated level of polymorphism and extreme genetic differentiation along the gradient. rfbC is part of an expression island involved in the production of the polysaccharide component of the protective envelope of the heterocyst, the specialized nitrogen‐fixing cell of these bacteria. SNP genotyping in the vicinity of rfbC revealed a ~5‐kbp region including a gene content polymorphism that is tightly associated with environmental temperature and therefore likely contains the target of selection. Two genes have been deleted both in the predominant haplotype found in the downstream region of White Creek and in strains from other Yellowstone populations of M. laminosus, which may result in the production of heterocysts with different envelope properties. This study implicates spatially varying selection in the maintenance of variation related to thermal performance at White Creek despite on‐going or recent gene flow.     

Low genetic diversity and small long-term population sizes in the spring endemic watercress darter, <Emphasis Type="Italic">Etheostoma nuchale</Emphasis>

Species endemic to coldwater springs in the southeastern United States are some of the rarest and most imperiled in this region, yet little is known about their genetic composition and conservation needs. Here, microsatellite based levels of genetic diversity and estimates of effective population size (N _e) were compared between a narrow spring endemic fish, Etheostoma nuchale, and its widespread stream-dwelling relative, E. swaini. We applied several analytical methods to assess how demographic history is reflected in contemporary levels of genetic diversity for populations of E. nuchale. Phylogenetic analyses based on mitochondrial and nuclear DNA sequence data revealed a complex history among E. nuchale and E. swaini, but suggested ancient divergence and historic periods of isolation since colonization of spring habitats by E. nuchale. Populations of E. nuchale have levels of genetic diversity approximately one-half that of E. swaini, a result most likely due to founder effects and recent bottlenecks. Statistically significant F _st values (0.05−0.27) and STRUCTURE analyses implied high levels of differentiation among E. nuchale populations. Estimates of current N _e suggest relatively consistent levels across populations of E. nuchale, but one population may suffer from habitat degradation. We suggest that high levels of population structure and low levels of genetic diversity may be typical in other spring endemics inhabiting this region. Therefore, effective management planning for these unique species will require a detailed knowledge of the genetic and demographic history of each population.     

Phylogenetic position of a threatened stag beetle, Lucanus datunensis (Coleoptera: Lucanidae) in Taiwan and implications for conservation

Among nine endemic Lucanus beetles in Taiwan, L. datunensis is the island’s smallest and most threatened species. It currently exists as only one population located in tall grasslands of Mt. Datun in the Yangmingshan National Park. Given the isolated population, unique subtropical grassland, and the threats resulting from human activities, L. datunensis raises immediate conservation concern for its long-term survival. Phylogenies reconstructed from combined mitochondrial cytochrome oxidase subunit 1 (1310 bps) and nuclear wingless (436 bps) genes were resolved and placed L. datunensis as a phylogenetically distinct species sister to L. fortunei from China. All 13 examined individuals of L. datunensis shared just one mitochondrial haplotype suggesting extremely low mitochondrial DNA diversity and a small effective population size. L. datunensis and morphologically closest L. miwai were distantly related and appear to have evolved in parallel the life history traits of a small body size and diurnal mate-searching behavior. We hypothesize that these habitat-associated characters are convergent adaptations that have evolved in response to shifts from forests to grasslands.     

How Quaternary geologic and climatic events in the southeastern margin of the Tibetan Plateau influence the genetic structure of small mammals: inferences from phylogeography of two rodents, <Emphasis Type="Italic">Neodon irene</Emphasis> and <Emphasis Type="Italic">Apodemus latronum</Emphasis>

Phylogeographical studies that focus on the southeastern margin of the Tibetan Plateau are limited. The complex terrain and unique geological history make it a particularly unusual region of the Tibetan Plateau. We carried out a phylogeographical study of two rodent species Neodon irene and Apodemus latronum using the mitochondrial cytochrome b gene sequences. High genetic diversities and deep phylogenetic splits were detected in both rodents. Some haplotypes from one sampling region fell into different evolutionary clades, but most haplotypes from the same sampling regions were clustered together with each other. The results of isolation by distance analysis further substantiated that their genetic diversities were structured along geography. Thus, there were high levels of geographical structure for both rodents. Demographic analyses implied a relatively constant population size for all samples of N. irene and A. latronum in history. However, clade B of N. irene and clade 3 of A. latronum experienced population expansions at 105–32 and 156–47 Kya, respectively. Through comparison with previous studies, we suggest the high mitochondrial DNA diversities in them are probably not a species-specific feature, but a common pattern for small mammals in this unique area. Details of the historical demography of these rodents revealed in this study could provide new insights into how rodents and possibly other small mammals in this region responded to the geological and climatic events.     

Widespread mito‐nuclear discordance with evidence for introgressive hybridization and selective sweeps in Lycaeides

We investigated the extent and potential cause(s) of mitochondrial introgression within the polytypic North American Lycaeides species complex (Lepidoptera). By comparing population genetic structure based on mitochondrial DNA (COI and COII) and nuclear DNA (251 polymorphic amplified fragment length polymorphism markers), we detected substantial mito‐nuclear discordance, primarily involving a single mitochondrial haplotype (h01), which is likely due to mitochondrial introgression between differentiated Lycaeides populations and/or species. We detected reduced mitochondrial genetic diversity relative to nuclear genetic diversity in populations where mitochondrial haplotype h01 occurs, suggesting that the spread of this haplotype was facilitated by selection. We found no evidence that haplotype h01 is associated with increased fitness (in terms of survival to eclosion, fresh adult weight, and adult longevity) in a polymorphic Lycaeides melissa population. However, we did find a positive association between mitochondrial haplotype h01 and infection by the endoparasitic bacterium Wolbachia in one out of three lineages tested. Linkage disequilibrium between mitochondrial haplotype h01 and Wolbachia infection status may have resulted in indirect selection favouring the spread of haplotype h01 in at least one lineage of North American Lycaeides. These results illustrate the potential for introgressive hybridization to produce substantial mito‐nuclear discordance and demonstrate that an individual's mitochondrial and nuclear genome may have strikingly different evolutionary histories resulting from non‐neutral processes and intrinsic differences in the inheritance and biology of these genomes.     

Comparison of population genetic patterns in two widespread freshwater mussels with contrasting life histories in western North America

We investigate population genetic structuring in Margaritifera falcata, a freshwater mussel native to western North America, across the majority of its geographical range. We find shallow rangewide genetic structure, strong population‐level structuring and very low population diversity in this species, using both mitochondrial sequence and nuclear microsatellite data. We contrast these patterns with previous findings in another freshwater mussel species group (Anodonta californiensis/A. nuttalliana) occupying the same continental region and many of the same watersheds. We conclude that differences are likely caused by contrasting life history attributes between genera, particularly host fish requirements and hermaphroditism. Further, we demonstrate the occurrence of a ‘hotspot’ for genetic diversity in both groups of mussels, occurring in the vicinity of the lower Columbia River drainage. We suggest that stream hierarchy may be responsible for this pattern and may produce similar patterns in other widespread freshwater species.     

Evolutionary distinctiveness and historical decline in genetic diversity in the Seychelles Black Parrot Coracopsis nigra barklyi

Island endemic species are acutely vulnerable to extinction as a result of stochastic and human impacts. Conservation of unique island biodiversity is high priority, and an understanding of the evolutionary history of vulnerable island species is important to inform conservation management. The Seychelles Black Parrot Coracopsis nigra barklyi is an island endemic threatened with extinction. The total population of 520–900 individuals is restricted to the 38‐km² island of Praslin, and it is one of the last few remaining endemic island parrots that survive in the Indian Ocean. We combined mitochondrial and microsatellite DNA markers with morphological data to examine the evolutionary distinctiveness of C. n. barklyi within Coracopsis, and to compare levels of genetic diversity between historical and contemporary specimens. Phylogenetic analyses revealed C. n. barklyi as sister to the remaining three C. nigra subspecies, and discriminant function analysis suggested the Seychelles Black Parrot is the smallest of the four subspecies. Higher levels of genetic diversity were observed in historical specimens, whereas only one mtDNA haplotype was observed in the contemporary specimens, suggesting that C. n. barklyi has lost genetic diversity as a consequence of substantial recent population decline. This study provides a first insight into the evolutionary, genetic and morphological processes that have shaped C. n. barklyi and provides an important perspective on this parrot's current genetic status to guide its future conservation management. Further ecological studies are essential but we suggest that C. n. barklyi should be managed as an evolutionary significant unit to conserve its unique evolutionary pathway.     

Near panmixia at the distribution‐wide scale but evidence of genetic differentiation in a geographically isolated population of the Terek Sandpiper Xenus cinereus

Populations from different parts of a species range may vary in their genetic structure, variation and dynamics. Geographically isolated populations or those located at the periphery of the range may differ from those located in the core of the range. Such peripheral populations may harbour genetic variation important for the adaptive potential of the species. We studied the distribution‐wide population genetic structure of the Terek Sandpiper Xenus cinereus using 13 microsatellite loci and the mitochondrial DNA (mtDNA) control region. In addition, we estimated whether genetic variation changes from the core towards the edge of the breeding range. We used the results to evaluate the management needs of the sampled populations. Distribution‐wide genetic structure was negligible; the only population that showed significant genetic differentiation was the geographically isolated Dnieper River basin population in Eastern Europe. The genetic variation of microsatellites decreased towards the edge of the distribution, supporting the abundant‐centre hypotheses in which the core area of the distribution preserves the most genetic variation; however, no such trend could be seen with mtDNA. Overall genetic variation was low and there were signs of past population contractions followed by expansion; this pattern is found in most northern waders. The current effective population size (N_e) is large, and therefore global conservation measures are not necessary. However, the marginal Dnieper River population needs to be considered its own management unit. In addition, the Finnish population warrants conservation actions due to its extremely small size and degree of isolation from the main range, which makes it vulnerable to genetic depletion.