Population genetic diversity of the endemic Sardinian newt Euproctus platycephalus: implications for conservation

The Sardinian mountain newt Euproctus platycephalus, endemic to the island of Sardinia, (Italy), is considered a rare and threatened species and is classed as critically endangered by IUCN. It inhabits streams, small lakes and pools on the main mountain systems of the island. Threats from climatic and anthropogenic factors have raised concerns for the long-term survival of newt populations on the island. MtDNA sequencing was used to investigate the genetic population structure and phylogeography of this endemic species. Patterns of genetic variation were assessed by sequencing the complete Dloop region and part of the 12SrRNA, from 74 individuals representing four different populations. Analyses of molecular variance suggest that populations are significantly differentiated, and the distribution of haplotypes across the island shows strong geographical structuring. However, phylogenetic analyses also suggest that the Sardinian population consists of two distinct mtDNA groups, which may reflect ancient isolation and expansion events. Population structure, evolutionary history of the species and implications for the conservation of newt populations are discussed.     

Current genetic isolation and fragmentation contrasts with historical connectivity in an alpine lizard (Cyclodomorphus praealtus) threatened by climate change

Assessing levels of genetic diversity, connectivity and historical demography for threatened species provides important information for conservation management. We used a combination of the mitochondrial ND4 gene and seven microsatellite markers to examine both historical and recent population genetic structure and demography of the threatened alpine she-oak skink, Cyclodomorphus praealtus. This species is restricted to the “sky islands” of the Australian alpine region. Based on mtDNA, the New South Wales and Victorian regions are reciprocally monophyletic and highly divergent, with among population variation of 0.9 and net sequence divergence of 4.28%, which suggests that they should be considered separate Evolutionary Significant Units for management purposes. The mtDNA data also indicate historical connectivity between the three Victorian populations. However, a model-based clustering analysis of microsatellite genotypes identified strong population structure in Victoria, with three distinct populations that have no current inter-population gene flow. This suggests that the Victorian populations are effectively isolated from each other, and is indicative of very low dispersal capacity and a high degree of habitat specialisation. This is reinforced by the substantially lower genetic diversity within the lowest elevation population compared to the other higher elevation populations. We found no genetic signature of major changes in effective population size. These data provide a baseline for assessing future impacts of climate change on the genetic structure of this alpine endemic species.     

Rescue of the Seychelles warbler on Cousin Island, Seychelles: the role of habitat restoration

Management policies to save threatened species are not always successful, often due to the lack of a scientific basis and evaluation of the species response. We describe the ecological studies and the conservation actions taken between 1985 and 1992 on Cousin Island (29 ha, Seychelles) to safeguard the future of the highly threatened Seychelles warbler (Acrocephalus sechellensis), which until 1988 only occurred on this island. A detailed field study was designed to (1) identify the key processes influencing warbler demography, (2) identify appropriate management techniques to increase the warbler population, and (3), assess the influence of the resulting habitat management. Since 1980 the island has been saturated with c. 115 territories and c. 320 birds. The warbler is purely insectivorous. Morinda (Morinda citrifolia), the most insect rich tree, is preferred for foraging. The higher the insect abundance (and Morinda cover) in territories the higher the reproductive success and survival of warblers. Insect numbers were highest in the central part of Cousin and decreased towards the coast. Coastal territories protected by a salt tolerant hedge of Scaevola (Scaevola taccada) had more insects and higher reproductive success than unprotected territories. Between 1990 and 1992 Morinda trees were planted on the island and Scaevola along the coast. Although these habitat restoration measures have not resulted in higher numbers of adult warblers and territories due to habitat saturation, they have been successful in terms of improving the quality of existing breeding territories and with that the reproductive success of breeding birds (including the number of territories producing recruits), and the exchange of individuals (genetic material) between territories. We provide evidence that the high reproductive potential of this species is likely to improve the resilience of the species to catastrophic events.     

The exploitation of sooty tern eggs in the seychelles

In the Seychelles, populations of sooty terns Sterna fuscata have declined this century, but the decline has not been as great as previously thought, and factors apart from over-exploitation of the eggs have been involved. A recent study of sooty tern ecology in the Seychelles has indicated that the present close season regulation serves no useful biological purpose. A system of quotas of eggs that may be taken from each island has not been effective due to chaning tern populations and to the voluntary cessation of collecting on some islands.This paper recommends that the eggs should in future be collected from two islands only, and that all other sooty tern colonies should be protected as far as is practicable. Exploitation should be restricted to the eggs of about 20% of the Seychelles/Amirantes population of sooty terns, but further research on the movements of the birds is urgently needed to determine the extent of inter-colony movements.     

Cryptic genetic diversity in “widespread” Southeast Asian bird species suggests that Philippine avian endemism is gravely underestimated

Mistakenly classifying morphologically cryptic endemic species as populations of widespread species potentially interferes with the conservation of biodiversity because undetected endemics that are imperilled may lack appropriate protection. It also impedes the reconstruction of the evolutionary history of a taxon by obscuring the number and distributional limits of species. Here, we present genetic and phylogenetic evidence corroborated by morphology that Philippine populations of seven widespread, non-migratory passerine birds might represent unrecognized, distinct species. An extrapolation based on this finding suggests that the proportion of endemic bird species in the Philippines could be much higher than currently estimated. This high degree of cryptic diversity in a well-studied, volant taxon implies that large numbers of unrecognized species can be expected in less thoroughly studied groups. We predict that genetic investigations of insular populations of widespread species will frequently reveal unrecognized island endemics, and because of the vulnerability of island habitats and their biota, these taxa may be particularly susceptible to extinction.     

Conservation of highly fragmented systems: The north temperate Alexander Archipelago

The Alexander Archipelago of Southeast Alaska encompasses over 2000 named islands that extend along 600 km of the North Pacific Coast. This review summarizes recent research on mammals of this largely unexplored region. Field inventories followed by preliminary molecular genetic analyses of selected mammals demonstrate substantial spatial structure consistent with both the dynamic geologic history of this boreal region and the highly insular landscape. New views of taxonomic diversity, biogeographic history, and contemporary population connectivity lay a framework for managing and conserving this complex biome. First, repeated Pleistocene glacial advances along the coast fragmented species, leaving clear genetic signatures and a strongly diversified fauna. Organisms recolonized the coast following deglaciation from multiple northern (Beringia), southern (West Coast and Continental) or North Pacific Coastal refugia. Several species are composed of multiple, genetically distinctive lineages (in some cases, incipient or new species) due to independent colonization histories from distinct, divergent source populations. Second, the insular landscape of the Alexander Archipelago has produced highly endemic populations. These centers of endemism should be thoughtfully managed as hotspots of lineage diversity. Until a better understanding of connectivity among these divergent populations is developed, each island should be considered an independent biological unit. Finally, industrial logging, mining, human encroachment, tourism, wildlife consumption, and invasive species should be stringently monitored and regulated with respect to impact on island endemics and ecosystems. A new conservation paradigm for the Tongass National Forest should be developed that is built around the recognition of the complexity of this incomparable island archipelago of the North Pacific. In particular, recognition of high diversity and endemism should be central to management plans.     

Insular pest control within a metapopulation context

Introduced pests threaten many species and their control is generally beneficial for conservation, particularly on islands where complete eradication is possible. Unfortunately on ‘nearshore’ islands neighbouring source populations exist and unaided reinvasion is likely. Pest control programmes at these sites thus require a metapopulation context to adequately manage movements between source and sink populations. We investigated the ecology of introduced ship rats (Rattus rattus) on a nearshore island, and gene flow with adjacent mainland populations, in order to understand the metapopulation dynamics and relative levels of pest control required within the landscape. We sampled the entire population by trapping (n = 30), achieving eradication, and found a low rat density (3.2 ha⁻¹) indicative of a sink population. Seed and other plant material constituted the major dietary component of rats. Despite its proximity to mainland source populations, the island population was genetically distinct with reduced allelic diversity caused by a recent reinvasion founder effect. Genetic analyses also detected recent migrants between the populations. In contrast, two mainland populations separated by a similar distance displayed complete genetic mixing. The small water gap therefore provides a sufficient barrier to lower the migration rate to the island and delay reinvasion, which nonetheless eventually happens. In order to maintain nearshore islands pest-free, conservation management will require a metapopulation approach simultaneously focusing on both island and source population pest control.     

Identifying the effectiveness and constraints of conservation interventions: A case study of the endangered lesser kestrel

The recognition of the rapid and ongoing biodiversity loss has been leading to increasing conservation efforts. To maximise conservation success it is important to evaluate when interventions are likely to be effective. In Portugal, previous research identified that lack of suitable nest-sites was limiting the populations of the endangered lesser kestrel (Falco naumanni). Consequently, a massive provisioning of artificial nest-sites and the implementation of a medium term monitoring scheme was established. Our study showed that artificial nest-site provisioning is an effective measure in mitigating the lack of traditional sites. The lesser kestrel population increased from 155–158 pairs in 1996 to 527–552 in 2007, with 52% breeding in artificial nests. We investigate the factors affecting colony growth and found that colony growth was positively affected by the provisioning of artificial nests but negatively affected by predation rate and human disturbance. Between 2003 and 2007, mean colony growth was estimated at 6.46 ± 1.86 pairs for colonies where artificial nests were provided and −0.69 ± 0.5 pairs in colonies without nest-site provisioning. Moreover, predation rate was significantly lower in artificial nests than in natural ones and, although the number of competitor pairs in lesser kestrel colonies increased, the proportion of nests occupied by competitor species decreased. High risk of collapse and restoration of rural abandoned farmhouses may jeopardize the future of the lesser kestrel in Portugal. Nest-site provisioning and the establishment of a protection status for buildings holding colonies are likely the most effective means to guarantee the long-term survival of this species in the area.     

Tortoises and tourists in the Western Indian ocean: The curieuse experiment

A colony of giant tortoises Geochelone gigantea from Aldabra Atoll was established in 1978 on the island of Curieuse in the granitic Seychelles, where tortoises have long been extinct. Ninety-five were landed in April 1978 and 78 in April 1980. The animals have shown considerable increases in wieght, and the first hatchling was found n February 1980. The main purpose of the colony is to provide a tourist attraction within easy reach of Mahé and deflect tourist pressure from Aldabra: at the same time the colony has considerable scientific potential. The environment and history of Curieuse are reviewed in the light of criteria initially established for the choice of an island for the project, and the future of the experiment is discussed.     

A biological survey of Aride Island nature reserve,Seychelles

Aride Island is one of the smaller granitic islands in the Republic of Seychelles in the Indian Ocean. The first permanent inhabitants settled before 1861 and since then man has extensively exploited the large seabird colonies on the island. In order to encourage more terns to lay, most of the trees on the island were coppiced annually. However, commercial exploitation and coppicing ceased in 1967 and in 1975 Aride was declared a Special Reserve by the Government of Seychelles. Two Oxford University Expeditions visited the island in 1975 and 1976 to complete a survey of the flora and fauna. The main objective of the survey was to collect baseline data for a monitoring programme so that the effectiveness of management policies could be ascertained in the future. The survey concluded that the status of most of the island's wildlife was satisfactory, although action needed to be taken to eliminate poaching, control certain introduced plants and to reduce disturbance of nesting seabirds to a minimum. The longer-term problems which may arise as a result of the regrowth of the trees are discussed.     

The distribution of native and introduced landbirds on Silhouette island,Seychelles, India ocean

The distributions of eight landbird species on Silhouette Island were mapped in the middle of the N-W monsson season, in order to assess any constraints on native birds due to (i) man's modification of habitats, and (ii) the presence of introduced birds. Patterns of distributional overlap suggested no cases of competitive exclusion between species pairs, and no direct interactions were observed. Instead, most native birds' ranges were related to the location of forest, though Seychelles sunbirds were very tolerant of man-made habitats; introduced species favoured human settlements and coconut plantations, though Indian mynahs also occupied most other habitats. It is unlikely that future development on the island will seriously threaten any of the native bird populations, but these are all species common elsewhere in the Seychelles.     

Ecological and genetic measurements of dispersal in a threatened dragonfly

Leucorrhinia caudalis is a rare dragonfly, threatened throughout its European distribution. The species was formerly widespread in the Swiss lowlands, but only a single population remained in the 1980s. However, a spread has recently been observed, with additional ponds being colonised, sometimes at considerable distance. Despite this evidence of recent long-distance dispersal, it is unknown whether L. caudalis regularly moves among ponds or whether this is a rather rare event. A combination of an ecological mark-resight and a population genetic study was applied to investigate contemporary dispersal and the genetic footprint of the recent population history of L. caudalis in Switzerland. DNA for genetic microsatellite analysis was extracted from exuviae. The mark-resight study and the genetic analysis gave congruent results. They showed that L. caudalis is mostly a sedentary species, with only a few contemporary dispersal events over distances up to 5 km being observed. The genetic analysis was in agreement with the recent population history of the Swiss populations. The oldest and largest population showed large genetic diversity and acted as source population for the recent spread of L. caudalis in Switzerland. Recurrent gene flow among this source population and close populations caused substantial local genetic variation in the latter, as well as low population differentiation. The two recently founded distant populations (?30 km distance) were genetically less diverse and highly differentiated. These distant populations and another recently colonised population also expressed signatures of genetic bottlenecks.     

Litter breakdown by the Seychelles giant millipede and the conservation of soil processes on Cousine Island, Seychelles

The Seychelles giant millipede, Seychelleptus seychellarum, is abundant on Cousine Island, Seychelles (ca. 4.4 ind m⁻²), where there are no alien invasive mammals as predators. This study of its feeding behaviour and activity pattern showed that its dietary range is wide, feeding mostly on leaf litter and fallen fruit. There were quantitative differences in the feeding behaviour and activity patterns of both sexes and immatures. Its ingestion rate for its size was relatively low, but its role in litter breakdown was substantial. It ingested 4.55% of the litter standing crop, and 17.19% of the daily litter fall every 24 h. Total faecal production was 2.90% of the total litter standing crop and 10.96% of the daily litter fall. This has a highly significant effect on Cousine Island which, being small and granitic, depends on nutrient cycling to maintain its ecological integrity, especially when seabirds are absent and not contributing to soil nutrient input. As this Seychelles endemic millipede has been extirpated from several islands, its continued conservation on the islands where it still occurs is not simply about conserving an endemic species, but also about maintaining intact a tropical ecosystem, with a keystone species.     

Ecology and conservation of two endangered subspecies of the leopard cat (Prionailurus bengalensis) on Japanese islands

The conservation of rare species on islands is a special challenge, especially when the islands are faced with increasing human impact. Two endangered wild felids in Japan provide a contrast that is useful for examining conservation strategies. The Iriomote cat (Prionailurus bengalensis iriomotensis) is endemic to Iriomotejima Island in Okinawa, and the Tsushima leopard cat (Prionailurus bengalensis euptilurus) occurs in the Tsushima islands in Japan, although a related subspecies found in the Korean Peninsula. Population size was approximately 100 individuals for each subspecies. While the population of Iriomote cat appears relatively stable, the population and abundance of the Tsushima leopard cat has decreased in recent decades. Because of their small population sizes and restricted habitats both are listed as endangered species/subspecies in Japan’s Red List, and the Iriomote cat is listed as an endangered subspecies in the IUCN Red List. Although both are similar-sized felids living on small islands, their ecological characteristics such as food habit, habitat selection, and density differ. These differences seem to be caused by the climate, the biological environment (the species composition of fauna in each island, and the presence of competitors), and the artificial background. The threats facing these two felids are also similar. Habitat destruction, traffic accidents, and negative influences by introduced species are the principal threats to be addressed for their conservation. At the same time, there are differences in the degree of impact by each threat, in each species’ conservation programs in practice, and in the stages of progress and operation of programs. These differences are partly because they have different ecological features and partly because the social background of each island, such as human population, main industry, and historical relationship between human and wildlife, are quite different. We will compare the ecology and state of these two wild felids and discuss the different conservational situations in relation to felid ecology and human society.     

Breeding biology and conservation of Hawksbill turtles, Eretmochelys imbricata L., on Cousin Island,Seychelles

A two-year tagging programme on Cousin Island, Seychelles showed that Hawksbills nested between September and March, each female nesting on average four times at intervals of 15 to 18 days. Females did not nest in successive years but the number of years between breeding attempts is not known. Twenty to thirty females now nest each year; the number of nests has increased markedly since the island became a nature reserve in 1968. Some females tried to nest on other islands in the same season, although those returning to Cousin usually did so within 50 m of their previous nest. The average clutch was 182, the largest recorded for any sea turtle, and the maximum estimate of average nest success was 86%. Present exploitation in the Seychelles is unsound from both biological and sociological points of view, exploiting the vulnerable breeding stock for a luxury product (‘tortoiseshell’) while wasting potentially valuable protein. It is recommended that future policy should concentrate instead on harvesting eggs for human consumption, while totally protecting adults, thus diverting valuable protein from natural predators to the local human population. This policy would exploit the stage of the turtle's life cycle best adapted to sustain high losses with minimum effect on breeding stocks, to the mutual benefit of turtle and local human populations.     

The roseate tern: World distribution and status of a threatened species

The roseate tern Sterna dougallii Montagu (Aves, Laridae) has a nearly cosmopolitan breeding distribution. The North American and European populations, the only ones which have been well-documented, have both declined drastically in the past decade, raising grave concern over the species' future. Literature search and correspondence reveal that the species currently maintains substantial breeding populations in the Indian Ocean, Caribbean, and Australasian regions. Most old reports provide no quantitative population estimates, while even many recent reports provide only vague estimates of population size. Nonetheless it has been possible to estimate regional populations in most cases to within one order of magnitude. The North American and Caribbean populations total about 10 000 pairs, while the European population is about 1500 pairs. The African population, including the Seychelles and the western Indian Ocean, may have 15 000 to 22 000 pairs. The documented world population is between 20 000 and 30 000 pairs, but the breeding populations of many areas are not yet documented. Substantial variation within and between regions in appearance and breeding biology indicates that each of the five named forms, at least, should be studied and managed separately.     

The effects of feral goats (Capra hircus) on island ecosystems

Feral goats (Capra hircus) are implicated in habitat destruction, and alteration of species composition on sensitive insular ecosystems. In the absence of population control, goats have become the ecologically dominant species on many islands with the results that numerous endemic plant species have been extirpated, or are threatened by excessive grazing. It is demonstrated that removal of goats can lead to rapid recovery of suppressed vegetation. The problems associated with excessive numbers of feral goats have rarely been studied or formally recognised. Extensive and intensive research is critically needed if affected island ecosystem are to be preserved or restored.     

What genetics tell us about the conservation of the critically endangered Balearic Shearwater?

The Balearic shearwater Puffinus mauretanicus is one of the most critically endangered seabirds in the world. The species is endemic to the Balearic archipelago, and conservation concerns are the low number of breeding pairs, the low adult survival, and the possible hybridization with a sibling species, the morphologically smaller Yelkouan shearwater (P. yelkouan). We sampled almost the entire breeding range of the species and analyzed the genetic variation at two mitochondrial DNA regions. No genetic evidence of population decline was found. Despite the observed philopatry, we detected a weak population structure mainly due to connectivity among colonies higher than expected, but also to a Pleistocene demographic expansion. Some colonies showed a high imbalance between immigration and emigration rates, suggesting spatial heterogeneity in patch quality. Genetic evidence of maternal introgression from the sibling species was reinforced, but almost only in a peripheral colony and not followed, at least to date, by the spread of the introgressed mtDNA lineages. Morphometric differences were not correlated with mtDNA haplotypes and introgression is probably due to a secondary contact between the two species several generations ago. Overall, results suggested that the very recent demographic decline in this critically endangered species has not yet decreased its genetic variability, and connectivity found among most colonies should help to reduce species extinction risk. Spreading of introgression should be monitored, but the species is not jeopardized at the moment by genetic factors and the major conservation actions should concentrate at enhancing adult survival.     

Genetic and morphological divergence in island and mainland birds: Informing conservation priorities

Evolutionary processes can complicate conservation efforts for species with uncertain taxonomic classifications and discrete geographic populations. Discordant morphological and genetic patterns across the geographic range of species further calls for the identification of evolutionary significant units for conservation. Using island and mainland populations of a small Australian passerine (the superb fairy-wren, Malurus cyaneus), we examine the relationship between morphological and genetic divergence among two subspecies, M. c. ashbyi (Kangaroo Island, South Australia) and M. c. leggei (South Australia, mainland), using eight microsatellite markers. Island birds showed clear evidence for morphological divergence, with a larger body size and thinner bill compared to mainland birds. Two genetic clusters were found using Bayesian methods, comprising mainland and island regions. Estimates of recent migration rates between all sites were very low (<2%). Morphological and genetic differentiation between island and mainland sites correlated significantly, but not when controlling for isolation by distance. Genetic and morphological substructure was evident with three distinct genetic clusters in each region. Males, the highly sedentary sex, appeared to drive correlations between morphological and genetic differentiation. Our study provides evidence that the subspecies classification of M. cyaneus in island and mainland regions encapsulates two independently diverging populations that can be recognised in conservation planning.