Large mainland populations of South Island robins retain greater genetic diversity than offshore island refuges

For conservation purposes islands are considered safe refuges for many species, particularly in regions where introduced predators form a major threat to the native fauna, but island populations are also known to possess low levels of genetic diversity. The New Zealand archipelago provides an ideal system to compare genetic diversity of large mainland populations where introduced predators are common, to that of smaller offshore islands, which serve as predator-free refuges. We assessed microsatellite variation in South Island robins (Petroica australis australis), and compared large mainland, small mainland, natural island and translocated island populations. Large mainland populations exhibited more polymorphic loci and higher number of alleles than small mainland and natural island populations. Genetic variation did not differ between natural and translocated island populations, even though one of the translocated populations was established with five individuals. Hatching failure was recorded in a subset of the populations and found to be significantly higher in translocated populations than in a large mainland population. Significant population differentiation was largely based on heterogeneity in allele frequencies (including fixation of alleles), as few unique alleles were observed. This study shows that large mainland populations retain higher levels of genetic diversity than natural and translocated island populations. It highlights the importance of protecting these mainland populations and using them as a source for new translocations. In the future, these populations may become extremely valuable for species conservation if existing island populations become adversely affected by low levels of genetic variation and do not persist.     

High genetic diversity in the remnant island population of hihi and the genetic consequences of re-introduction

The maintenance of genetic diversity is thought to be fundamental for the conservation of threatened species. It is therefore important to understand how genetic diversity is affected by the re-introduction of threatened species. We use establishment history and genetic data from the remnant and re-introduced populations of a New Zealand endemic bird, the hihi Notiomystis cincta, to understand genetic diversity loss and quantify the genetic effects of re-introduction. Our data do not support any recent bottleneck events in the remnant population. Furthermore, all genetic diversity measures indicate the remnant hihi population has retained high levels of genetic diversity relative to other New Zealand avifauna with similar histories of decline. Genetic diversity (N(A) , alleles per locus, allelic richness, F(IS) and H(S) ) did not significantly decrease in new hihi populations founded through re-introduction when compared to their source populations, except in the Kapiti Island population (allelic richness and H(S) ) which had very slow post-re-introduction population growth. The N(e) /N(c) ratio in the remnant population was high, but decreased in first-level re-introductions, which together with significant genetic differentiation between populations (F(ST) & Fisher's exact tests) suggest that extant populations are diverging as a result of founder effects and drift. Importantly, simulations of future allele loss predict that the number of alleles lost will be higher in populations with a slow population growth, fewer founding individuals and with nonrandom mating. Interestingly, this species has very high levels of extra-pair paternity which may reduce reproductive variance by allowing social and floater males to reproduce a life history trait that together with a large remnant population size may help maintain higher levels of genetic diversity than expected.     

No evidence for loss of genetic variation following sequential translocations in extant populations of a genetically depauperate species

Repeated population bottlenecks can lead to loss of genetic variation and normally should be avoided in threatened species to preserve evolutionary potential. We examined the effect of repeated bottlenecks, in the form of sequential translocations, on loss of genetic variation in a threatened passerine, the saddleback (Philesturnus carunculatus carunculatus), a species that has recovered from a remnant population with historically low levels of genetic variation. Although a slight but nonsignificant loss of alleles may have occurred between the first-order translocation and the extirpated source population, first-, second-, and third-order translocated populations had very similar levels of genetic variation to each other. The most obvious difference among the seven island populations appeared to lie in allele frequencies with little or no loss of alleles among extant populations. Although sequential translocations are known to cause loss of variation in genetically diverse species, our study indicates that genetically depauperate species may be less sensitive to loss of genetic variation through founder events presumably because the few remaining alleles are well represented in founding individuals. These results show that ancient bottlenecks may have a long-term effect on genetic variation, to the extent that contemporary population bottlenecks may leave no appreciable genetic signature. Our results suggest that subjecting genetically depauperate endangered species to sequential translocations could be used to rapidly establish new populations without further eroding genetic variation.     

Patterns of Genetic and Reproductive Traits Differentiation in Mainland vs. Corsican Populations of Bumblebees

Populations on islands often exhibit lower levels of genetic variation and ecomorphological divergence compared to their mainland relatives. While phenotypic differentiation in characters, such as size or shape among insular organisms, has been well studied, insular differentiation in quantitative reproductive traits involved in chemical communication has received very little attention to date. Here, we investigated the impact of insularity on two syntopic bumblebee species pairs: one including species that are phylogenetically related (Bombus terrestris and B. lucorum), and the other including species that interact ecologically (B. terrestris and its specific nest inquiline B. vestalis). For each bumblebee species, we characterized the patterns of variation and differentiation of insular (Corsican) vs. mainland (European) populations (i) with four genes (nuclear and mitochondrial, 3781 bp) and (ii) in the chemical composition of male marking secretions (MMS), a key trait for mate attraction in bumblebees, by gas chromatography-mass spectrometry (GC-MS). Our results provide evidence for genetic differentiation in Corsican bumblebees and show that, contrary to theoretical expectations, island populations of bumblebees exhibit levels of genetic variation similar to the mainland populations. Likewise, our comparative chemical analyses of MMS indicate that Corsican populations of bumblebees are significantly differentiated from the mainland yet they hold comparative levels of within-population MMS variability compared to the mainland. Therefore, insularity has led Corsican populations to diverge both genetically and chemically from their mainland relatives, presumably through genetic drift, but without a decrease of genetic diversity in island populations. We hypothesize that MMS divergence in Corsican bumblebees was driven by a persistent lack of gene flow with mainland populations and reinforced by the preference of Corsican females for sympatric (Corsican) MMS. The impoverished Corsican bumblebee fauna has not led to relaxation of stabilizing selection on MMS but to consistent differentiation chemical reproductive traits on the island.     

Genetic differentiation in Philippine bats of the genera Cynopterus and Haplonycteris

Genetic variation and differentiation in six island populations of two species ( Cynopterus brachyotis Müller and Haplonycteris fischeri Lawrence) of Philippine fruit bats (Chiroptera, Pteropodidae) were analysed using allozyme electrophoresis. Cynopterus is eurytopic and widespread in southeast Asia; Haplonycteris is stenotopic and endemic to the Philippines. Genetic variability within populations is consistently higher in Cynopterus , but differentiation between populations is much more pronounced in Haplonycteris. Genetic variation is not significantly correlated with island size in either species, but a positive trend is present in both. Levels of gene flow are sufficiently low to allow differentiation by genetic drift alone in Haplonycteris ( Nm = 0.05), but not in Cynopterus ( Nm = 7.5). There is no significant association between genetic distance and distance between sampling sites; however, between-population differentiation is positively related to degree of geographic isolation during Pleistocene periods of low sea level and to vagility and consequent levels of gene flow among populations. Significant effects of population size on genetic differentiation were not found. Genetic distance matrices for the two species share a common structure that is similar to patterns of mammalian faunal similarity for the Philippines as a whole, suggesting similar effects of geographic and/or environmental factors.     

Low genetic diversity and high genetic divergence caused by inbreeding and geographical isolation in the populations of endangered species Loropetalum subcordatum (Hamamelidaceae) endemic to China

Loropetalum subcordatum (Hamamelidaceae) is one of the most endangered angiosperm species in China. It is narrowly distributed in a few localities in the evergreen broadleaved forest of southern China. Up to now only a few dozen remnant individuals have been found in the four extant populations. In this project, we studied its genetic diversity and population genetic structure using the high resolution molecular marker of amplified fragment length polymorphism. In total, 47 individuals from all the four populations (including all individuals in three populations) were analyzed. Comparably low genetic diversity within populations was revealed and significantly high genetic differentiation among the populations was detected. Four independent groups were identified which corresponded with their geographical ranges. Autogamy is considered to be the major factor contributing to the low genetic variation and high genetic divergence within this species. In addition, small population size, restricted distribution range, geographical isolation and limited seed dispersal may also contribute to the low genetic diversity and high population genetic differentiation. Clonal reproduction was inferred to occur in the two island populations. Suggestions for conservation strategies are provided to preserve the genetic resources of this species.     

Genetic Structure of Remnant Populations and Cultivars of Switchgrass (Panicum virgatum) in the Context of Prairie Conservation and Restoration

Switchgrass (Panicum virgatum L.) is a dominant, perennial C₄ grass of North American tallgrass prairies with cultivars that are widely used in grassland restoration, pastures, and landscaping. However, these cultivars may be genetically dissimilar to small, remnant populations, raising concerns about altered genetic composition of native populations through gene flow. To address this issue on a local scale in Ohio and Illinois, we used microsatellite markers to characterize genetic diversity and differentiation of 10 remnant prairie populations (5 in each state) and 8 common cultivars. The bulk of genetic variation was found to reside within rather than among wild populations, consistent with the outcrossing breeding system of switchgrass. Genetic diversity was similar among the remnant populations despite large differences in area (approximately 2–2,590 ha), highlighting the importance of small native populations as reservoirs of variation and potential seed sources for prairie restoration. Cultivars generally had similar levels of variation to the wild populations, but we found clear genetic dissimilarity between wild and cultivated gene pools (especially for Kanlow, but also Trailblazer, Blackwell, Dacotah, Summer, and Sunburst cultivars). This suggests that using cultivars in local prairie restoration efforts may alter the genetic composition of wild populations. Whether such changes are deemed as negative depends on the cultivar under consideration and specific conservation goals for preserving native switchgrass populations. Patterns of genetic variation in remnant prairie populations and potential cultivar sources can be used to develop guidelines for restoration as well as future planting of cultivars for biofuels.     

Blood-protein allele frequencies and phylogenetic relationships in Macaca: A review

Allele-frequency data have been assembled for 35 blood-protein loci in 17 of 19 recognized species of Macaca based on 29 published electrophoretic studies; studies of inbred captive colonies have been excluded. Data for 22 polymorphic loci are tabulated in detail for 43 geographic populations of these species. Calculated F_ST values provide a measure of intergroup genetic differentiation at various hierarchical levels—troop, locality, province, country or island, species, species group; polymorphism indices measure genetic variation. The greatest intraspecific genetic differentiation occurs at the level of island populations within species. The pattern of genetic variation among island populations appears to be relictual, suggesting that the reduced genetic variability of island populations of macaques is a result of postisolation genetic drift rather than founder effect. Interspecific relationships were investigated by means of a jackknifed Fitch-Margoliash algorithm, using Papio as outgroup. Phylogenetic inferences based on morphology and zoogeography. The reduced genetic variability that frequently characterizes insular macaque populations complicates phylogenetic interpretation of blood-protein evidence.     

Genetic and morphometric diversity in Wallacea: geographical patterning in the horse shoe bat, Rhinolophus affinis

Genetic and morphometric variation was examined in eleven island populations of the horse‐shoe bat, Rhinolophus affinis, at the easterly end of this widespread species’ range and encompassing the Australian–Oriental biogeographic interface. Allozyme variation revealed mean heterozygosity levels within islands of 0.047, which is near the mammalian average. However, heterozygosity tended to decline from west to east as populations approached the periphery of the species’ distribution, and was lowest in those islands that were separated by the greatest sea‐crossing from source populations. There is extensive between‐island genetic differentiation (mean F_ST = 0.40) and relationships between islands are associated with their arrangement in geographical space; genetic distance is correlated with geographical distance and the genetic arrangement of islands is associated with longitude. The arrangement of islands as indicated by variation in body and skull metrics is also associated with their geographical positions, and the metric and genetic measures are themselves associated. While other taxa in the region have shown genetic‐geographical concordances, R. affinis is the only one that displays concordant patterns in metrical features. These patterns in biological diversity are interpreted as arising from the sequential island population structure and clines in key biogeographic gradients.     

Genetic consequences of trumpeter swan (Cygnus buccinator) reintroductions

Relocation programs are often initiated to restore threatened species to previously occupied portions of their range. A primary challenge of restoration efforts is to translocate individuals in a way that prevents loss of genetic diversity and decreases differentiation relative to source populations—a challenge that becomes increasingly difficult when remnant populations of the species are already genetically depauperate. Trumpeter swans were previously extirpated in the entire eastern half of their range. Physical translocations of birds over the last 70 years have restored the species to portions of its historical range. Despite the long history of management, there has been little monitoring of the genetic outcomes of these restoration attempts. We assessed the consequences of this reintroduction program by comparing patterns of genetic variation at 17 microsatellite loci across four restoration flocks (three wild-released, one captive) and their source populations. We found that a wild-released population established from a single source displayed a trend toward reduced genetic diversity relative to and significant genetic differentiation from its source population, though small founder population effects may also explain this pattern. Wild-released flocks restored from multiple populations maintained source levels of genetic variation and lacked significant differentiation from at least one of their sources. Further, the flock originating from a single source revealed significantly lower levels of genetic variation than those established from multiple sources. The distribution of genetic variation in the captive flock was similar to its source. While the case of trumpeter swans provides evidence that restorations from multiple versus single source populations may better preserve natural levels of genetic diversity, more studies are needed to understand the general applicability of this management strategy.     

Genetic Similarity of Island Populations of Tent Caterpillars during Successive Outbreaks

Cyclic or fluctuating populations experience regular periods of low population density. Genetic bottlenecks during these periods could give rise to temporal or spatial genetic differentiation of populations. High levels of movement among increasing populations, however, could ameliorate any differences and could also synchronize the dynamics of geographically separated populations. We use microsatellite markers to investigate the genetic differentiation of four island and one mainland population of western tent caterpillars, Malacosoma californicum pluviale, in two periods of peak or pre-peak density separated by 8 years. Populations showed high levels of genetic variation and little genetic differentiation either temporally between peaks or spatially among sites. Mitochondrial haplotypes were also shared between one island population and one mainland population in the two years studied. An isolation-by-distance analysis showed the F_ST values of the two geographically closest populations to have the highest level of differentiation in both years. We conclude that high levels of dispersal among populations maintain both synchrony of population dynamics and override potential genetic differentiation that might occur during population troughs. As far we are aware, this is the first time that genetic similarity between temporally separated population outbreaks in insects has been investigated. A review of genetic data for both vertebrate and invertebrate species of cyclic animals shows that a lack of spatial genetic differentiation is typical, and may result from high levels of dispersal associated with fluctuating dynamics.     

Population genetic diversity and structure within and among disjunct populations of <Emphasis Type="Italic">Alnus maritima</Emphasis> (seaside alder) using microsatellites

Small, isolated populations are prone to genetic drift and high levels of inbreeding that can threaten their long-term survival. Alnus maritima persists exclusively in three groups of small, highly disjunct, regional populations in the Delmarva Peninsula, Georgia, and Oklahoma. Trees in the three regions are recognized as separate subspecies. Microsatellite markers were used to measure fine-scale population genetic diversity and structure (1) within and among regions and (2) within and among populations in each region. Compared to a previous study utilizing allozymes, microsatellite data show higher levels of variation, lower levels of inbreeding, but similar levels of genetic differentiation among regions. Significant genetic differentiation was detected among regions and among distinct populations within regions. Genetic differentiation was significantly correlated with geographic distance among regional populations, but not among populations within regions. Populations, therefore, likely represent fragments of formerly extensive networks of populations that have decayed and retracted due to competition with other species better adapted to the shadier habitats of late-succession environments. The unique genetic features of populations within different regions should be considered as part of future conservation efforts.     

Implications of contrasting patterns of genetic variability in two vespertilionid bats from the Indonesian archipelago

Wallacean island populations of two Vespertilioninae bats, Myotis muricola and Scotophilus kuhlii , which have similar geographical ranges, showed marked contrast in the amount and pattern of genetic variation. Within islands, genetic variation was on average much higher in M. muricola but declined from west to east, whereas all populations of S. kuhlii had uniformly low levels of genetic variation by mammalian standards. S. kuhlii showed little genetic differentiation between islands and estimates of gene flow were substantial whereas island populations of M. muricola differed markedly and there was a strong isolation-by-distance effect associated with the extent of the sea crossing between islands. Furthermore, the lower mean heterozygosity and small genetic distances between eastern island populations of M. muricola is evidence that there has been a bottleneck associated with the colonization of this area. The attenuation of genetic diversity to the east is also seen in some other mammalian species and may indicate limits to dispersal and have implications for species management. The patterns of variability in S. kuhlii may be a consequence of its strong dispersal capacity and close association with human activity, which, together with other factors, suggest a panmictic population.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 83 , 421–431.     

Genetic structure of the Canarian palm tree (Phoenix canariensis) at the island scale: does the ‘island within islands’ concept apply to species with high colonisation ability?

• Oceanic islands are dynamic settings that often promote within‐island patterns of strong population differentiation. Species with high colonisation abilities, however, are less likely to be affected by genetic barriers, but island size may impact on species genetic structure regardless of dispersal ability.
• The aim of the present study was to identify the patterns and factors responsible for the structure of genetic diversity at the island scale in Phoenix canariensis, a palm species with high dispersal potential. To this end, we conducted extensive population sampling on the three Canary Islands where the species is more abundant and assessed patterns of genetic variation at eight microsatellite loci, considering different within‐island scales.
• Our analyses revealed significant genetic structure on each of the three islands analysed, but the patterns and level of structure differed greatly among islands. Thus, genetic differentiation fitted an isolation‐by‐distance pattern on islands with high population densities (La Gomera and Gran Canaria), but such a pattern was not found on Tenerife due to strong isolation between colonised areas. In addition, we found a positive correlation between population geographic isolation and fine‐scale genetic structure.
• This study highlights that island size is not necessarily a factor causing strong population differentiation on large islands, whereas high colonisation ability does not always promote genetic connectivity among neighbouring populations. The spatial distribution of populations (i.e. landscape occupancy) can thus be a more important driver of plant genetic structure than other island, or species′ life‐history attributes.

     

Genetic variation and conservation of the endangered endemic Anagyris latifolia Brouss. ex Willd. (Leguminosae) from the Canary Islands

Anagyris latifolia is an endemic and endangered species from the Canary Islands, whose distribution is limited to four islands, with less than 400 individuals in fragmented and isolated localities. RAPD markers have been used to assess the genetic diversity and genetic differentiation of its populations, in order to formulate appropriate management and conservation genetics strategies. Nine polymorphic primers generated 74 polymorphic DNA fragments. Genetic variation levels detected in Anagyris latifolia were significant high (H = 0.200; P% = 97.3), principal coordinates analysis and genetic differentiation coefficient showed a high degree of genetic differentiation between islands, without a define east-to-west stepping stone colonization route. AMOVA analysis showed that of the total genetic variation detected, 32.43% was maintained among islands, 20.73% contained among population within islands, and 46.84% resided within populations. According to these results, management strategies should be focused on each island separately.     

Genetic differentiation among populations of marine algae

Most of the information for genetic differentiation among populations of marine algae is from studies on ecotypic variation. Physiological ecotypes have been described for individuals showing different responses to temperature and salinity conditions. Morphological ecotypes have also been found associated with areas differing in wave exposure or different intertidal positions. Little is known on how genetic variation is organized within and between populations of marine algae. The occurrence of ecotypic variation in some species is evidence for genetic differentiation among populations resulting from selection by the local environment. The rate of dispersal and subsequent gene flow will also affect the level of differentiation among populations. In species with low dispersal, differentiation can arise through chance founder events or random genetic drift. The few studies available have shown that species of algae exhibit a range of dispersal capabilities. This information can be useful for predicting the potential level of genetic differentiation among populations of these species. Crossing experiments with several species of algae have shown that populations separated by a considerable distance can be interfertile. In some cases individuals from these populations have been found to be morphologically distinct. Crosses have been used to study the genetic basis of this variation and are evidence for genetic differentiation among the populations sampled. Genetic variation of enzyme proteins detected by electrophoresis provides an additional method for measuring genetic variation within and between populations of marine algae. Electrophoretic methods have previously been used to study systematic problems in algae. However, there have been few attempts to use electrophoretic variation to study the genetic structure of populations of marine algae. This approach is outlined and includes some of the potential problems associated with interpreting electrophoretic data. Studies of electrophoretic variation in natural populations ofEnteromorpha linza from Long island Sound are used as an example. This species was found to reproduce only asexually. Despite a dispersing spore stage, genetic differentiation was found on a microgeographic scale and was correlated with differences in the local environment of some of the populations. Similar studies on other species, and especially sexually reproducing species, will add to a growing understanding of the evolutionary genetics of marine algae.Paper presented at the Seaweed Biogeography Workshop of the International Working Group on Seaweed Biogeography, held from 3–7 April 1984 at the Department of Marine Biology, Rijksuniversiteit Groningen (The Netherlands). Convenor: C. van den Hoek.     

Differences among six woody perennials native to Northern Europe in their level of genetic differentiation and adaptive potential at fine local scale

The ability of perennial species to adapt their phenology to present and future temperature conditions is important for their ability to retain high fitness compared to other competing plant species, pests, and pathogens. Many transplanting studies with forest tree species have previously reported substantial genetic differentiation among populations within their native range. However, the question of “how local is local” is still highly debated in conservation biology because studies on genetic patterns of variation within and among populations at the local scale are limited and scattered. In this study, we compare the level of genetic differentiation among populations of six different perennial plant species based on their variation in spring flushing. We assess the level of additive genetic variation present within the local population. For all six species, we find significant differentiation among populations from sites with mean annual temperature ranging between 7.4°C and 8.4°C. The observed variation can only be partly explained by the climate at the site of origin. Most clear relationship between early flushing and higher average spring temperature is observed for the three wind‐pollinated species in the study, while the relations are much less clear for the three insect‐pollinated species. This supports that pollination system can influence the balance between genetic drift and natural selection and thereby influence the level of local adaptation in long‐lived species. On the positive side, we find that the native populations of woody plant species have maintained high levels of additive genetic variation in spring phenology, although this also differs substantially among the six studied species.     

Genetic structure of island populations of the endangered bat <Emphasis Type="Italic">Hipposideros turpis turpis</Emphasis>: implications for conservation

Efforts for the conservation of the endangered bat species Hipposideros turpis turpis in southern Japan are hampered by a lack of information about its biology and natural history and by the increasing effect of human activities. In an attempt to address some of the conservation challenges faced by this species, we studied the genetic structure and dispersal of intra- and interisland populations using six species-specific microsatellite markers. In particular, we sought to establish the relationship between island populations and to define effective management units for conservation. Pairwise co-ancestry index (F _ST) analysis, analysis of molecular variance, and Bayesian clustering suggested the presence of significant genetic differentiation between islands but little differentiation within them. The small Yonaguni Island population appeared to be not only geographically isolated, but also genetically isolated. This population is at the greatest risk of extinction, considering its size and low genetic variation. The larger populations on Iriomote and Ishigaki Islands are genetically related to each other to a greater degree and exhibit higher genetic variation than the Yonaguni Island population. This suggests that these two island populations should be included in a single management unit, while bats from Yonaguni Island should be managed independently and given higher priority for conservation. Actions such as defining vegetation corridors between colonies, as well as building gates at the entrance of the largest known colony, should be included in the conservation agenda of this still poorly known species.     

Genetic Diversity in Remnant Mainland and “Pristine” Island Populations of Three Endemic Australian Macropodids (Marsupialia): Macropus Eugenii, Lagorchestes Hirsutus and Petrogale Lateralis

Since European settlement, mainland Australia has experienced a wave of mammal extinctions and population declines. However, some species have persisted on off-shore islands, which are now viewed as important wildlife refuges. In this study, we assessed the level of genetic diversity, at 7–11 microsatellite loci, in island and remnant mainland populations of three endemic species of macropodid marsupial; the tammar wallaby Macropus eugenii(n = 92); rufous hare-wallaby Lagorchestes hirsutus(n = 40) and black-footed rock-wallaby Petrogale lateralis(n = 164). There was a consistent pattern of significantly higher levels of microsatellite diversity in the remnant mainland population (A= 4.9–13.9; He= 0.61–0.86) of each species compared to conspecific pristine island populations (A= 1.2–3.7; He= 0.05–0.44). These marked differences are even apparent where island populations currently have a substantially larger census size. In addition, island populations were substantially inbred (Fe= 0.49–0.91). Although island populations have been insulated from the relatively recent threatening processes operating on the mainland, they have nevertheless been significantly impacted by increased inbreeding and the substantial erosion of genetic diversity. Despite the difficulties of ensuring the survival of remnant mainland populations, they appear to retain substantially more genetic diversity than their island counterparts and therefore are more likely to contribute to the long-term persistence of their species. These data also demonstrate that small remnant mainland populations (n < 10–20) are often capable of rapid recovery and are not necessarily genetically depauperate.     

Genetic structure and diversity of the koala population in South Gippsland,Victoria: a remnant population of high conservation significance

In the Australian state of Victoria, the history of koalas and their management has resulted in the homogenisation and reduction of genetic diversity in many contemporary populations. Decreased genetic diversity may reduce a species’ ability to adapt to future environmental pressures such as climate change or disease. The South Gippsland koala population is considered to be unique in Victoria, as it is believed to be a remnant population, not originating from managed populations that have low genetic variation. This study investigated genetic structure and diversity of koalas in South Gippsland, with comparison to other populations in Victoria (French Island/Cape Otway, FI and Raymond Island, RI), New South Wales and south east Queensland. Population analyses were undertaken using both microsatellite genotype and mitochondrial DNA sequence data. Non-invasive sampling of koala scats was used to source koala DNA, allowing 222 South Gippsland koalas to be genotyped. Using nuclear data the South Gippsland koala population was found to be significantly differentiated (D_jost 95% CI SG–RI?=?0.03–0.06 and SG–FI?=?0.08–012) and more diverse (A_R 95% CI SG?=?4.7–5.6, RI?=?3.1–3.3, FI?=?3.0–3.3; p?=?0.001) than other Victorian koala populations, supporting the premise that koalas in the South Gippsland region are part of a remnant population, not derived from translocated island stock. These results were also supported by mitochondrial data where eight haplotypes (Pc4, Pc17, Pc26, Pc27, and Pc56–Pc59) were identified in South Gippsland while a single haplotype (Pc27) was found in all island koalas tested. Compared to other Victorian koala populations, greater genetic diversity found in South Gippsland koalas, may provide this population with a greater chance of survival in the face of future environmental pressures. The South Gippsland koala population is, therefore, of high conservation significance, warranting the implementation of strategies to conserve this population and its diversity into the future.