Linking habitat quality with genetic diversity: a lesson from great bustards in Spain

The effects of habitat loss and fragmentation on the genetic structure and variability of wild populations have received wide empirical support and theoretical formalization. By contrast, the effects of habitat quality seem largely underinvestigated, partly due to technical difficulties in properly assessing habitat quality. In this study, we combine geographic information system (GIS)-based habitat-quality modelling with a landscape genetics approach based on mitochondrial DNA markers to evaluate the possible influence of habitat quality on the levels and distribution of genetic diversity in a range of natural populations (n = 15) of Otis tarda throughout Spain. Ninety-three percent of the population represented by our countrywide sample lives in good-quality habitats, while 4.5% and 2.5% occur respectively in intermediate and poor habitats. Habitat quality was highly correlated with patch size, population size and population density, indicating the reliability and predictive power of the habitat suitability model. Genetic diversity was significantly correlated with habitat quality, size and density of the population, but not with patch size. Three of a total of 20 existing matrilineages from the species’ current genetic pool are restricted to poor-quality habitats. This study therefore highlights the importance of considering both population genetics and habitat quality in a species of high conservation priority.     

Genetic effects of habitat fragmentation and population isolation on Etheostoma raneyi (Percidae)

The use of genetic methods to quantify the effects of anthropogenic habitat fragmentation on population structure has become increasingly common. However, in today’s highly fragmented habitats, researchers have sometimes concluded that populations are currently genetically isolated due to habitat fragmentation without testing the possibility that populations were genetically isolated before European settlement. Etheostoma raneyi is a benthic headwater fish restricted to river drainages in northern Mississippi, USA, that has a suite of adaptive traits that correlate with poor dispersal ability. Aquatic habitat within this area has been extensively modified, primarily by flood-control projects, and populations in headwater streams have possibly become genetically isolated from one another. We used microsatellite markers to quantify genetic structure as well as contemporary and historical gene flow across the range of the species. Results indicated that genetically distinct populations exist in each headwater stream analyzed, current gene flow rates are lower than historical rates, most genetic variation is partitioned among populations, and populations in the Yocona River drainage show lower levels of genetic diversity than populations in the Tallahatchie River drainage and other Etheostoma species. All populations have negative F_IS scores, of which roughly half are significant relative to Hardy–Weinberg expectations, perhaps due to small population sizes. We conclude that anthropogenic habitat alteration and fragmentation has had a profoundly negative impact on the species by isolating E. raneyi within headwater stream reaches. Further research is needed to inform conservation strategies, but populations in the Yocona River drainage are in dire need of management action. Carefully planned human-mediated dispersal and habitat restoration should be explored as management options across the range of the species.     

Genetic restoration in the eastern collared lizard under prescribed woodland burning

Eastern collared lizards of the Ozarks live in glades—open, rocky habitats embedded in a woodland matrix. Past fire suppression had made the woodlands a barrier to dispersal, leading to habitat destruction, fragmentation and local extinction. Reintroduced populations of lizards were subjected to 10 years of habitat fragmentation under continued fire suppression followed by twelve years of landscape restoration with prescribed burns. Prior to prescribed burning, genetic diversity decreased within glades and differentiation increased among glades. With woodland burning, genetic diversity within glades first decreased during an expanding colonization phase, but then increased as a dynamically stable metapopulation was established. Population differentiation among glades also stabilized in the metapopulation under weak isolation‐by‐distance. This study is one of the first to examine the genetic changes in a species of conservation concern throughout all the stages of decline and recovery and shows the importance of landscape‐level restoration for maintaining the genetic integrity of populations. This study also demonstrates how mark–recapture and genetic data together can yield detailed insight into metapopulation dynamics that would be impossible from just one type of data alone.     

Genetic population structure of the sagebrush Brewer’s sparrow, <Emphasis Type="Italic">Spizella breweri breweri</Emphasis>, in a fragmented landscape at the northern range periphery

Assessing the genetic consequences of habitat fragmentation is a crucial step in conservation planning for species in endangered habitats. We tested for the impact of natural habitat fragmentation on gene flow and genetic diversity in seven northern breeding locations of the sagebrush Brewer’s sparrow, Spizella breweri breweri. Genetic analyses using five highly variable DNA microsatellite loci suggested that individuals sampled within a sagebrush landscape fragmented by natural elements such as coniferous forest, comprise a single genetic population and that gene flow among them is unimpeded. We posit that juvenile dispersal links seemingly isolated breeding locales of this species, and discuss implications of our findings for conservation of migratory songbirds in the northern portion of their ranges in light of potential shifts in distribution due to climate change.     

Multilocus approach reveals an incipient differentiation process in the Stone-curlew, <Emphasis Type="Italic">Burhinus oedicnemus</Emphasis> around the Mediterranean basin

The Stone-curlew Burhinus oedicnemus, a steppe bird species, is mainly distributed in the Mediterranean and Macaronesian regions, which are considered hotspots of biodiversity with priority for animal and plant species richness conservation. In this study, we investigated the genetic diversity of the Stone-curlew in the Mediterranean basin and in the Canary Islands by applying a multilocus approach. We analysed mitochondrial and nuclear markers in order to evaluate the genetic structure and the congruence between morphological subspecies and geographic samples. We found a significant level of genetic differentiation between Mediterranean and Canary Island populations with all markers. Both in the Mediterranean basin and in the Canary Islands, we found a significant level of genetic diversity with nuclear markers only. We identified seven population groups, including insular populations. The four subspecies described for the Western Palaearctic were confirmed with some changes in distribution range. In spite of habitat fragmentation and negative population trend, the Stone-curlew showed a significant level of genetic diversity and gene flow among continental populations. However, islands constitute important reservoirs of genetic diversity and a potential for the evolution of the species.     

High genetic diversity of the endangered Iberian three‐spined stickleback (Gasterosteus aculeatus) at the Mediterranean edge of its range

1. The three‐spined stickleback (Gasterosteus aculeatus) on the Iberian Peninsula is only distributed in freshwater habitats and has completely disappeared from most of its range, mainly as a consequence of habitat degradation and invasive fish introductions. Genetic investigations have shown that Mediterranean‐Adriatic sticklebacks constitute an evolutionarily significant unit. Here, we present the first genetic data for Iberian populations living on the southern edge of the stickleback’s range. We used microsatellite markers to study gene diversity, population structure and genetic demography of stickleback populations. 2. High genetic differentiation among collections yielded a model of four genetically homogeneous units related to geography. The observed pattern of isolation by distance resulted mainly from the hydrographical pattern and limited gene flow among rivers. Moreover, low levels of gene diversity, high isolation and recent bottleneck events, which have led to small or even critical effective population sizes in several locations, could be explained by additional recent anthropogenic fragmentation. 3. We defined at least four evolutionarily significant units threatened by habitat fragmentation in north‐eastern Iberian sticklebacks. Because they retain long evolutionary histories, these populations should be considered of high conservation priority, and urgent management measures should be implemented.     

Genetic diversity in butterflies: Interactive effects of habitat fragmentation and climate-driven range expansion

Some species are expanding their ranges polewards during current climate warming. However, anthropogenic fragmentation of suitable habitat is affecting expansion rates and here we investigate interactions between range expansion, habitat fragmentation and genetic diversity. We examined three closely related Satyrinae butterflies, which differ in their habitat associations, from six sites along a transect in England from distribution core to expanding range margin. There was a significant decline in allozyme variation towards an expanding range margin in Pararge aegeria, which has the most restricted habitat availability, but not in Pyronia tithonus whose habitat is more widely available, or in a non-expanding 'control species' (Maniola jurtina). Moreover, data from another transect in Scotland indicated that declines in genetic diversity in P. aegeria were evident only on the transect in England, which had greater habitat fragmentation. Our results indicate that fragmentation of breeding habitats leads to more severe founder events during colonization, resulting in reduced diversity in marginal populations in more specialist species. The continued widespread loss of suitable habitats in the future may increase the likelihood of loss of genetic diversity in expanding species, which may affect whether or not species can adapt to future environmental change.     

Effects of dams and their environmental impacts on the genetic diversity and connectivity of freshwater mussel populations in Poyang Lake Basin,China

1. Habitat fragmentation is one of the main threats to biodiversity. Barriers to dispersal caused by anthropogenic habitat alteration may affect phylogeographic patterns in freshwater mussels. Knowledge of the phylogenetic and phylogeographic patterns of unionoids is vital to inform protection of their biodiversity.
2. Here, we assessed influences of dams and their environmental effects on the genetic diversity and population connectivity of a broadly distributed freshwater mussel, Nodularia douglasiae, in Poyang Lake Basin.
3. The results showed high genetic diversity in areas without dams and low genetic diversity in areas with dams. High genetic differentiation and low gene flow were found among the 11 populations. Genetic variation was significantly correlated with dissolved oxygen levels.
4. The observation of low genetic diversity in populations separated by dams indicated that those populations were subjected to genetic erosion and demographic decline because they are disconnected from other populations with higher diversity. High genetic differentiation and low gene flow among the 11 populations could be correlated with anthropogenic habitat alteration.
5. These results indicated that anthropogenic habitat alterations have led to the decline in freshwater mussel diversity. Therefore, we recommend maintaining favourable habitat conditions and connectivity of rivers or lakes, and strengthening study of life histories with host-test experiments to identify potential host fish species to strengthen the knowledge base underpinning freshwater mussel conservation.

     

High gene flow in epiphytic ferns despite habitat loss and fragmentation

Tropical montane forests suffer from increasing fragmentation and replacement by other types of land-use such as coffee plantations. These processes are known to affect gene flow and genetic structure of plant populations. Epiphytes are particularly vulnerable because they depend on their supporting trees for their entire life-cycle. We compared population genetic structure and genetic diversity derived from AFLP markers of two epiphytic fern species differing in their ability to colonize secondary habitats. One species, Pleopeltis crassinervata, is a successful colonizer of shade trees and isolated trees whereas the other species, Polypodium rhodopleuron, is restricted to forests with anthropogenic separation leading to significant isolation between populations. By far most genetic variation was distributed within rather than among populations in both species, and a genetic admixture analysis did not reveal any clustering. Gene flow exceeded by far the benchmark of one migrant per generation to prevent genetic divergence between populations in both species. Though populations are threatened by habitat loss, long-distance dispersal is likely to support gene flow even between distant populations, which efficiently delays genetic isolation. Consequently, populations may rather be threatened by ecological consequences of habitat loss and fragmentation.     

Genetic structure of <Emphasis Type="Italic">Saxifraga tridactylites</Emphasis> (Saxifragaceae) from natural and man-made habitats

In contrast to many declining plant species Saxifraga tridactylites extended its distribution range in the man-made landscape of central Europe. The species naturally colonizes rocks and calcareous grasslands, but has also spread enormously in anthropogenic habitats such as railway constructions during the last decades. To analyze the genetic structure of the species 216 individuals from 8 populations in natural and 5 populations in man-made habitats were studied using AFLPs. The molecular analysis resulted in 250 scorable fragments. Population variability, measured as Nei’s gene diversity, Shannon’s Information Index and percentage of polymorphic bands, was slightly but not significantly higher in populations from natural habitats and was not correlated with population size. Mantel test indicated no significant correlation between pairwise genetic (Φ_PT) and geographic distances. An analysis of molecular variance revealed significant differentiation between the two habitat types. About 9% variability were observed between natural and man-made habitats, 21% among populations within these two habitats and 70% within populations. In a neighbour joining cluster analysis populations from natural and man-made habitats were clearly separated from each other. Populations of S. tridactylites from man-made habitats do, therefore, not suffer from reduced genetic diversity. The observed genetic differentiation between populations from man-made and natural habitats could be due to reduced gene flow and/or habitat specific selection. However, the results of the study clearly demonstrate human impact on the genetic structure of plant populations in man-made landscapes.     

Adaptation to Ephemeral Habitat May Overcome Natural Barriers and Severe Habitat Fragmentation in a Fire-Dependent Species,the Bachman's Sparrow (Peucaea aestivalis)

Bachman''s Sparrow (Peucaea aestivalis) is a fire-dependent species that has undergone range-wide population declines in recent decades. We examined genetic diversity in Bachman''s Sparrows to determine whether natural barriers have led to distinct population units and to assess the effect of anthropogenic habitat loss and fragmentation. Genetic diversity was examined across the geographic range by genotyping 226 individuals at 18 microsatellite loci and sequencing 48 individuals at mitochondrial and nuclear genes. Multiple analyses consistently demonstrated little genetic structure and high levels of genetic variation, suggesting that populations are panmictic. Based on these genetic data, separate management units/subspecies designations or translocations to promote gene flow among fragmented populations do not appear to be necessary. Panmixia in Bachman''s Sparrow may be a consequence of an historical range expansion and retraction. Alternatively, high vagility in Bachman''s Sparrow may be an adaptation to the ephemeral, fire-mediated habitat that this species prefers. In recent times, high vagility also appears to have offset inbreeding and loss of genetic diversity in highly fragmented habitat.     

Population structuring in mountain zebras (<Emphasis Type="Italic">Equus zebra</Emphasis>): The molecular consequences of divergent demographic histories

The endangered mountain zebra (Equus zebra) is endemic to the semi-arid inhospitable mountainous escarpments of southern Africa. The species is divided taxonomically into two geographically separated subspecies, each with differing recent population histories. In Namibia, Hartmann’s mountain zebra (E. z. hartmannae) is common and occurs in large free-ranging populations, whereas in South Africa, prolonged hunting and habitat destruction over the last 300 years has decimated populations of the Cape mountain zebra (E. z. zebra). In this study, we investigate the consequences of these divergent demographic histories for population genetic diversity and structure. We also examine the phylogeographic relationship between the two taxonomic groups. Genetic information was obtained at 15 microsatellite loci for 291 individuals from a total of 10 populations as well as 445 bp of the mitochondrial control region sequence data from 77 individuals. Both model-based and standard analytical approaches were used to examine the data. Both types of marker returned levels of diversity and structure that were consistent with population history. Low genetic variation within individual Cape mountain zebra populations, the characteristic indicator of population fragmentation and drift, was offset by moderate variation in the entire E. z. zebra sample. This implies that higher levels of diversity still exist within the Cape mountain zebra gene pool. A management strategy that entailed the mixing of aboriginal populations is therefore advocated in order to halt the further loss of Cape mountain zebra genetic diversity. Allele frequencies in Hartmann’s mountain zebra were relatively resilient to demographic fluctuations. Due to the high incidence of mitochondrial haplotype sharing between populations, the hypothesis that Cape and Hartmann’s mountain zebra mitochondrial lineages were reciprocally monophyletic was not supported. However, the presence of private alleles at nuclear loci rendered the two subspecies genetically distinct evolutionary significant units.     

Population structure and landscape genetics in the endangered subterranean rodent Ctenomys porteousi

In order to devise adequate conservation and management strategies for endangered species, it is important to incorporate a reliable understanding of its spatial population structure, detecting the existence of demographic partitions throughout its geographical range and characterizing the distribution of its genetic diversity. Moreover, in species that occupy fragmented habitats it is essential to know how landscape characteristics may affect the genetic connectivity among populations. In this study we use eight microsatellite markers to analyze population structure and gene flow patterns in the complete geographic range of the endangered rodent Ctenomys porteousi. Also, we use landscape genetics approaches to evaluate the effects of landscape configuration on the genetic connectivity among populations. In spite of geographical proximity of the sampling sites (8–27 km between the nearest sites) and the absence of marked barriers to individual movement, strong population structure and low values of gene flow were observed. Genetic differentiation among sampling sites was consistent with a simple model of isolation by distance, where peripheral areas showed higher population differentiation than those sites located in the central area of the species’ distribution. Landscape genetics analysis suggested that habitat fragmentation at regional level has affected the distribution of genetic variation among populations. The distance of sampling sites to areas of the landscape having higher habitat connectivity was the environmental factor most strongly related to population genetic structure. In general, our results indicate strong genetic structure in C. porteousi, even at a small spatial scale, and suggest that habitat fragmentation could increase the population differentiation.     

Low genetic diversity and limited genetic structure across the range of the critically endangered Mexican howler monkey (Alouatta palliata mexicana)

Genetic diversity provides populations with the possibility to persist in ever-changing environments, where selective regimes change over time. Therefore, the long-term survival of a population may be affected by its level of genetic diversity. The Mexican howler monkey (Alouatta palliata mexicana) is a critically endangered primate restricted to southeast Mexico. Here, we evaluate the genetic diversity and population structure of this subspecies based on 83 individuals from 31 groups sampled across the distribution range of the subspecies, using 29 microsatellite loci. Our results revealed extremely low genetic diversity (H_O = 0.21, H_E = 0.29) compared to studies of other A. palliata populations and to other Alouatta species. Principal component analysis, a Bayesian clustering method, and analyses of molecular variance did not detect strong signatures of genetic differentiation among geographic populations of this subspecies. Although we detect small but significant F_ST values between populations, they can be explained by a pattern of isolation by distance. These results and the presence of unique alleles in different populations highlight the importance of implementing conservation efforts in multiple populations across the distribution range of A. p. mexicana to preserve its already low genetic diversity. This is especially important given current levels of population isolation due to the extreme habitat fragmentation across the distribution range of this primate.     

RAPD analysis of genetic diversity and population genetic structure of Stipa krylovii reshov. in Inner Mongolia steppe

Random amplified polymorphic DNA (RAPD) analysis was used to characterize the genetic diversity and population genetic structure of Stipa krylovii populations in Inner Mongolia steppe of North China. Thirteen 10-bp oligonucleotide primers, which generated 237 RAPD bands, were used to analyze 90 plants of five populations from three regions, meadow steppe, typical steppe and desert steppe, from the east to the west. The genetic diversity of Stipa krylovii that was revealed by observed number of alleles (na), expected number of alleles (ne), Nei’s diversity index (h), Shannon’s diversity index (H), amplificated loci, polymorphic loci and the percentage of polymorphic loci (PPB) increased from the east to the west. The Pearson’s correlation analysis between genetic diversity parameters and ecological parameters indicated that the genetic diversity of Stipa krylovii was associated with precipitation and cumulative temperature variations along the longitude (humidity were calculated by precipitation and cumulative temperature). Dendrogram based on Jaccard’s genetic distance showed that the individuals from the same population formed a single subgroup. Although most variation (56.85%) was within populations, there was high genetic differentiation among populations of Stipa krylovii, high differentiation within and between regions by AMOVA analysis. Either Nei’s unbiased genetic distance (G _ST) or gene flow (Nm) among pairwise populations was not correlated with geographical distance by Mantel’s test (P > 0.05), suggesting that there was no consistency with the isolation by distance model in these populations. Natural selection may have played a role in affecting the genetic diversity and population structure, but habitat destruction and degradation in northem grassland in China may be the main factor responsible for high genetic differentiation among populations, within and among regions. The text was submitted by the authors in English.     

生境片断化对植物种群遗传结构的影响及植物遗传多样性保护

生境片断化是指大而连续的生境变成空间隔离的小种群的现象。生境片断化对植物种群遗传效应包括生境片断化过程中的取样效应及其后的小种群效应（遗传漂变、近交等）。理论研究表明,生境片断化后,植物种群的遗传变异程度将降低,而残留的小种群间的遗传分化程度将升高。然而对一些植物的研究表明,生境片断化对植物种群的遗传效应要受其他一些因素的影响,如世代长度、片断化时间、片断种群的大小、基因流的改变等。最后,针对生境     

Genetic assessment of lake sturgeon (<Emphasis Type="Italic">Acipenser fulvescens</Emphasis>) population structure in the Ottawa River

Lake sturgeon (Acipenser fulvescens) are of conservation concern throughout their range. Many populations are dependent on fluvial habitats which have been increasingly impacted and fragmented by dams and human development. Although lake sturgeon were once abundant in the Ottawa River and its tributaries, historical commercial harvests and other anthropogenic factors caused severe declines and low contemporary numbers in lake sturgeon populations. Contemporary habitat fragmentation by dams may be increasing isolation among habitat patches and local rates of decline, raising concerns for persistence of local populations. We used microsatellite DNA markers to assess population structure and diversity of lake sturgeon in the Ottawa River, and analyzed samples from 10 sites that represent more than 500 km of riverine habitat. To test for evidence of anthropogenic fragmentation, patterns of genetic diversity and connectivity within and among river segments were tested for concordance with geographic location, separation by distance and obstacles to migration, considering both natural and artificial barriers as well as barrier age. Despite extensive habitat fragmentation throughout the Ottawa River, statistical analyses failed to refute panmixia of lake sturgeon in this system. Although the long generation time of lake sturgeon appears to have effectively guarded against the negative genetic impacts of habitat fragmentation and loss so far, evidence from demographic studies indicates that restoring connectivity among habitats is needed for the long-term conservation and management of this species throughout this river system.     

Habitat fragmentation,genetic diversity,and inbreeding depression in a threatened grassland legume: is genetic rescue necessary?

Kincaid’s lupine (Lupinus oreganus), a threatened perennial legume of western Oregon grasslands, is composed of small, fragmented populations that have consistently low natural seed set, suggesting they may have accumulated high enough levels of genetic load to be candidates for genetic rescue. We used simple sequence repeat (SSR) loci, both nuclear DNA and chloroplast DNA, to screen populations throughout the species’ range for evidence of severe inbreeding and recent genetic bottlenecks due to habitat fragmentation. After genotyping about 40% of the known populations, only one of 24 populations had strong statistical evidence for a recent genetic bottleneck (H _e > H _eq). Both mean nSSR fixation coefficients and genetic diversity did not statistically differ between very small, small, medium, and large lupine population size classes. Within population chloroplast DNA haplotype number was high for an animal pollinated species, ≈4.2 haplotypes/population, and within population haplotype diversity was also relatively evenly distributed. Within population patterns of nSSR and cpSSR genetic diversity suggest that genetic diversity has not been lost over the last century of habitat fragmentation. With genet lifespan thought to exceed 100 years, overlap of several to many generations, and substantial reductions in seed set from inbreeding depression that shifts cohort composition towards those generated by outcrossing events, Kincaid’s lupine is likely maintain the currently high levels of within population genetic diversity. The case of Kincaid’s lupine provides an example of how the assumptions of severe inbreeding depression with small population size and habitat fragmentation can be inaccurate.     

Molecular biodiversity in the moss <Emphasis Type="Italic">Leptodon smithii</Emphasis> (Neckeraceae) in relation to habitat disturbance and fragmentation

Bryophytes seem particularly suitable to investigate genetic diversity in relation to habitat disturbance due to their large employment as bioindicators and to the recent application of molecular markers to moss population studies. Genetic variation and structure were analysed in seven urban, extraurban and remote populations of Leptodon smithii, an epiphytic moss of Quercus ilex, a phanerogamic species of Mediterranean climax vegetation. A total of 210 individual shoots were DNA extracted and amplified with internal simple sequence repeat (ISSR) primers, and 54 haplotypes were identified. An uneven distribution of haplotype number and frequencies was observed among sites, with a higher number of haplotypes and more homogeneous haplotype frequencies in the extraurban/remote populations. Molecular diversity indices were overall higher in the extraurban sites than in the urban ones. Multilocus linkage disequilibrium values were in line with the occurrence of sexual/asexual reproduction in the seven populations. The isolation-by-distance model was not supported by Mantel test among sites; however, within-population fixation index (F_ST) highlighted a clear relation between genetic and physic distances among trees, suggesting a limited dispersal range for L. smithii’s spores. The genetic structure was mainly affected by population size, wood structure and extent, and genetic drift consequent to habitat fragmentation and human-induced disturbance.     

Investigating genetic diversity and habitat dynamics in Plantago brutia (Plantaginaceae), implications for the management of narrow endemics in Mediterranean mountain pastures

Many factors have contributed to the richness of narrow endemics in the Mediterranean, including long-lasting human impact on pristine landscapes. The abandonment of traditional land-use practices is causing forest recovery throughout the Mediterranean mountains, by increasing reduction and fragmentation of open habitats. We investigated the population genetic structure and habitat dynamics of Plantago brutia Ten., a narrow endemic in mountain pastures of S Italy. Some plants were cultivated in the botanical garden to explore the species' breeding system. Genetic diversity was evaluated based on inter-simple sequence repeat (ISSR) polymorphisms in 150 individuals from most of known stands. Recent dynamics in the species habitat were checked over a 14-year period. Flower phenology, stigma receptivity and experimental pollinations revealed protogyny and self-incompatibility. With the exception of very small and isolated populations, high genetic diversity was found at the species and population level. amova revealed weak differentiation among populations, and the Mantel test suggested absence of isolation-by-distance. Multivariate analysis of population and genetic data distinguished the populations based on genetic richness, size and isolation. Landscape analyses confirmed recent reduction and isolation of potentially suitable habitats. Low selfing, recent isolation and probable seed exchange may have preserved P. brutia populations from higher loss of genetic diversity. Nonetheless, data related to very small populations suggest that this species may suffer further fragmentation and isolation. To preserve most of the species' genetic richness, future management efforts should consider the large and isolated populations recognised in our analyses.