Ecological and socio-economic factors affecting extinction risk in parrots

Parrots (Psittaciformes) are among the most threatened bird orders with 28 % (111 of 398) of extant species classified as threatened under IUCN criteria. We confirmed that parrots have a lower Red List Index (higher aggregate extinction risk) than other comparable bird groups, and modeled the factors associated with extinction risk. Our analyses included intrinsic biological, life history and ecological attributes, external anthropogenic threats, and socio-economic variables associated with the countries where the parrot species occur, while we controlled for phylogenetic dependence among species. We found that the likelihood of parrot species being classified as threatened was less for species with larger historical distribution size, but was greater for species with high forest dependency, large body size, long generation time, and greater proportion of the human population living in urban areas in the countries encompassing the parrots’ home ranges. The severity of extinction risk (from vulnerable to critically endangered) was positively related to the per capita gross domestic product (GDP) of the countries of occurrence, endemism to a single country, and lower for species used as pets. A disproportionate number of 16 extinct parrot species were endemic to islands and single countries, and were large bodied, habitat specialists. Agriculture, hunting, trapping, and logging are the most frequent threats to parrots worldwide, with variation in importance among regions. We use multiple methods to rank countries with disproportionately high numbers of threatened parrot species. Our results promote understanding of global and regional factors associated with endangerment in this highly threatened taxonomic group, and will enhance the prioritization of conservation actions.     

Nesting Habitat of the Lilac-crowned Parrot in a Modified Landscape in Mexico

Parrot populations are being increasingly pressured to occupy modified or fragmented landscapes, yet little is known of the habitat requirements of most species, particularly with regard to the effects on breeding habitat. We evaluated nesting habitat of the lilac-crowned parrot Amazona finschi in the modified landscape of coastal Michoacan in Mexico. We located 90 parrot nests in 12 tree species in Michoacan, with lilac-crowned parrots presenting a narrow niche-breadth of tree species used for nesting. Considering an additional 82 nest trees recorded for lilac-crowned parrots in Jalisco, we determined a 51 percent similarity in cavity resource use by parrots in the two dry forest regions. Overall, the predominant nest tree species with 76 percent of nests were Astronium graveolens , Piranhea mexicana , Brosimum alicastrum , and Tabebuia spp., all characteristic of semi-deciduous forest. Only 8 percent of nests occurred in trees characteristic of deciduous forest. Parrots utilized large trees with canopy level cavities as nest sites, and preferred conserved semi-deciduous forest for nesting, with fewer nests than expected in deciduous forest and transformed agricultural land. Nest areas in semi-deciduous forest occurred on significantly steeper terrain, as remnant semi-deciduous forest is restricted to steep ridges and canyons. Those parrot nests in modified habitats and forest patches were located near to continuous forest, with nest trees in open agricultural land being significantly closer to continuous forest than nests in disturbed forest patches. These results demonstrate the importance of conserved semi-deciduous forest as breeding habitat for the threatened, endemic lilac-crowned parrot, making wild populations of the species vulnerable to the high rate of transformation and fragmentation of tropical dry forest.     

Abundance and abundance change in the world's parrots

Estimates of population density and abundance change (differences in density or encounter rates across land uses or time periods) form the cornerstone of much of our knowledge of species' responses to environmental conditions, extinction risks and potential conservation actions. Gathering baseline data on abundance of the world's c. 10 000 bird species and monitoring trends in the light of rapidly changing environmental and harvest pressures is a daunting prospect. With this in mind, we review literature on population densities and abundance changes across habitats in one of the world's largest and most threatened bird families, the parrots (Psittaciformes), to identify gaps in knowledge, model phylogenetic and other influences on abundance, and seek patterns that might guide thinking for data‐deficient taxa and situations. Density estimates were found for only 25% of 356 parrot species. Abundance change data were similarly limited and most came from logged forest, with very few comparisons across different anthropogenic habitats. Threatened species were no more likely to have a density estimate than non‐threatened species, and were less likely to have estimates of abundance change. Exploratory generalized linear mixed models indicated that densities are most influenced by genus, and are generally higher within protected areas than outside. It is unclear whether the latter effect stems from habitat protection, a reduction in poaching or both, but protected areas appear to be beneficial for parrots. Individual members of the ‘parakeet’ genera (e.g. Pyrrhura and Eos) were predictably abundant, whereas within larger‐bodied genera such as Ara (macaws), species were predictably uncommon (< 10 individuals per km²) and there was a long tail of extreme rarity. Responses of parrots to habitat change were highly variable, with natural variation in parrot abundance across different primary forests as great as that between primary forest and human‐altered forests. The speed at which environmental change is affecting the world's parrots far outstrips that of our current capacity to track their abundance and we assess the likely scale of data deficiency in this and other bird groups. Developments in survey and analysis methods such as variants of distance sampling and the integration of niche modelling with point density estimation may increase our effectiveness in monitoring parrots and other important and threatened bird groups.     

Alarming evidence of widespread mite extinctions in the shadows of plant,insect and vertebrate extinctions

This paper, which addresses the issue of the extinction of mite species at the global scale for the first time, highlights mite diversity, assesses the evidence for an extinction process, discusses contributing factors and estimates losses. The ~1 250 000 mite species occupy an enormous variety of terrestrial and freshwater ecosystems from the equator to the polar regions and to high altitudes. Some groups provide essential ecosystem services, including the incorporation of organic matter into the soil. The maintenance of mite diversity is inextricably linked to the continuance of floristic diversity, habitat complexity and insect diversity. The majority of mite species are assumed to be in the tropical rainforests, of which >50% has been destroyed or severely degraded. Most biodiversity hotspots are in tropical forests; endemic phytoseiid mite species are at least 17 times more concentrated in the hotspots than outside. Habitat destruction and degradation continue on an enormous scale, with increasing human population growth and resource consumption the overarching drivers of extinction. Moreover, climate change is likely to be worsening the effects of the other drivers at an increasing rate. The small body of direct evidence and a considerable body of indirect evidence strongly suggest the continuing, widespread extinction of mite species. Based on estimates of overall biodiversity loss, ~15% of mite species were likely to have become extinct by 2000, with losses currently expected to increase by between 0.6% and 6.0% by 2060. More detailed information on both spatial differences in mite assemblages and anthropogenic threats worldwide is crucial because they underpin the total number of species and their vulnerability to extinction, respectively. The rapid expansion of the protected area estate to capture the maximum possible area of ecosystem heterogeneity, especially in the biodiversity hotspots, is essential, as is best practice management of these areas.     

The Future of Tropical Forest Species1

Deforestation and habitat loss are widely expected to precipitate an extinction crisis among tropical forest species. Humans cause deforestation, and humans living in rural settings have the greatest impact on extant forest area in the tropics. Current human demographic trends, including slowing population growth and intense urbanization, give reason to hope that deforestation will slow, natural forest regeneration through secondary succession will accelerate, and the widely anticipated mass extinction of tropical forest species will be avoided. Here, we show that the proportion of potential forest cover remaining is closely correlated with human population density among countries, in both the tropics and the temperate zone. We use United Nations population projections and continent‐specific relationships between both total and rural population density and forest remaining today to project future tropical forest cover. Our projections suggest that deforestation rates will decrease as population growth slows, and that a much larger area will continue to be forested than previous studies suggest. Tropical forests retracted to smaller areas during repeated Pleistocene glacial events in Africa and more recently in selected areas that supported large prehistoric human populations. Despite many caveats, these projections and observations provide hope that many tropical forest species will be able to survive the current wave of deforestation and human population growth. A strategy to preserve tropical biodiversity might include policies to improve conditions in tropical urban settings to hasten urbanization and preemptive conservation efforts in countries with large areas of extant forest and large projected rates of future human population growth. We hope that this first attempt inspires others to produce better models of future tropical forest cover and associated policy recommendations.     

Habitat loss and the limits to endangered species recovery

Canada is one of the last places on earth with extensive wilderness areas, yet the number of Canadian species threatened with extinction continues to rise every year. Using satellite‐derived land use data, we find that habitat loss explains most of the variation in numbers of endangered species across Canada. Habitat loss within species ranges is, therefore, likely to be the leading factor inhibiting their recovery. We measured habitat loss individually within the known ranges of 243 terrestrial species at risk of extinction across Canada. Recovery potential, as measured by extent of natural habitat within each species’ range, is bimodally distributed, but less than 50% of the range of the majority of Canada's species at risk is natural habitat and there is no detectable habitat remaining for 16 of the 243 species at risk. There were no differences in the recovery potential of species categorized either by threat level (special concern, threatened, or endangered) or taxon. Despite having extensive wilderness areas, Canada has similar rates of endangerment to other countries in the Americas, underlining the effect of severe habitat loss to intensive agriculture that has occurred in Canada's most biologically diverse regions. Improvements to protected areas networks and especially cooperative conservation activities with private landowners will do the most to improve the recovery prospects of species at risk in Canada.     

Comprehensive Red List Assessment Reveals Exceptionally High Extinction Risk to Madagascar Palms

The establishment of baseline IUCN Red List assessments for plants is a crucial step in conservation planning. Nowhere is this more important than in biodiversity hotspots that are subject to significant anthropogenic pressures, such as Madagascar. Here, all Madagascar palm species are assessed using the IUCN Red List categories and criteria, version 3.1. Our results indicate that 83% of the 192 endemic species are threatened, nearly four times the proportion estimated for plants globally and exceeding estimates for all other comprehensively evaluated plant groups in Madagascar. Compared with a previous assessment in 1995, the number of Endangered and Critically Endangered species has substantially increased, due to the discovery of 28 new species since 1995, most of which are highly threatened. The conservation status of most species included in both the 1995 and the current assessments has not changed. Where change occurred, more species have moved to lower threat categories than to higher categories, because of improved knowledge of species and their distributions, rather than a decrease in extinction risk. However, some cases of genuine deterioration in conservation status were also identified. Palms in Madagascar are primarily threatened by habitat loss due to agriculture and biological resource use through direct exploitation or collateral damage. The recent extension of Madagascar’s protected area network is highly beneficial for palms, substantially increasing the number of threatened species populations included within reserves. Notably, three of the eight most important protected areas for palms are newly designated. However, 28 threatened and data deficient species are not protected by the expanded network, including some Critically Endangered species. Moreover, many species occurring in protected areas are still threatened, indicating that threatening processes persist even in reserves. Definitive implementation of the new protected areas combined with local community engagement are essential for the survival of Madagascar’s palms.     

Terrestrial Mammal Occupancy in the Context of Widespread Forest Loss and a Proposed Interoceanic Canal in Nicaragua's Decreasingly Remote South Caribbean Region

Central America is experiencing rapid forest loss and habitat degradation both inside and outside of protected areas. Despite increasing deforestation, the Caribbean region of Nicaragua plays an important role in the survival or extinction of large mammal populations in Central America given that it still retains core areas of habitat for large mammal species. The proposed interoceanic canal project that would bisect the southern half of this Caribbean region represents a new threat that, combined with an advancing agricultural frontier, could affect populations of large mammal species such as jaguars, white-lipped peccaries, and Baird’s tapirs. We used occupancy models to examine the relative occupancy probabilities for an assemblage of terrestrial mammals in the south Caribbean region of Nicaragua to identify current core areas for our study species and conduct a preliminary evaluation of the potential impacts of the proposed interoceanic canal. We modeled a community level distribution of eight species with varying levels of sensitivity to human encroachment and a range of habitat associations. Our model results reveal three priority areas for terrestrial mammal conservation in our study area. The mapped predictions show that the only remaining area of suitable habitat for large mammals in the path of the proposed interoceanic canal is a relatively thin strip of forest that runs along the Caribbean Coast. In light of these findings, we propose five recommendations that will help ensure the conservation of this area of the proposed canal route as suitable habitat for our study species.     

Global diversity of dragonflies (Odonata) in freshwater

Larvae of almost all of the 5,680 species of the insect order Odonata (dragonflies and damselflies) are dependent on freshwater habitats. Both larvae and adults are predators. The order is relatively well studied, and the actual number of species may be close to 7,000. Many species have small distributional ranges, and are habitat specialists, including inhabitants of alpine mountain bogs, seepage areas in tropical rain forests, and waterfalls. They are often successfully used as indicators for environmental health and conservation management. The highest diversity is found in flowing waters in rain forests of the tropics, the Oriental and Neotropical regions being the most speciose. This paper discusses diversity, summarises the biogeography of dragonflies in the different biogeographical regions and gives the total number of species and genera per family per biogeographical region. Examples are given of areas of particular diversity, in terms of areas of endemism, presence of ancient lineages or remarkable recent radiations but no well-based review of areas with high endemism of dragonflies is available so far. The conservation status of dragonflies is briefly discussed. Species confined to small remnants of forest in the tropics are most under threat of extinction by human activities. Guest editors: E. V. Balian, C. Lévêque, H. Segers and K. Martens Freshwater Animal Diversity Assessment     

Conservation of Red Colobus and Their Habitats

A review of the conservation status of red colobus indicates that ≥38.9% of the taxa are threatened with extinction in the near future. Although no taxon of red colobus appears to have gone extinct, many of their populations have. The major threats are hunting and habitat loss and degradation, but in some cases intrinsic biotic factors, such as predator-prey imbalance, are leading to serious declines in populations. I propose a general framework for evaluating conservation problems and possible solutions, with an emphasis on distinguishing between proximate and ultimate variables and the time scales involved. In general, most viable populations of red colobus occur in well-protected forests; usually national parks. I proffer recommendations to improve the conservation status of the parks, which will benefit red colobus and most other tropical forest species.     

Predicted distributions,niche comparisons,and conservation status of the spotted linsang (<Emphasis Type="Italic">Prionodon pardicolor</Emphasis>) and banded linsang (<Emphasis Type="Italic">Prionodon linsang</Emphasis>)

Knowledge of a species’ distribution and habitat preferences is of paramount importance when assessing its conservation status. We used accurately recorded occurrence records and ecological niche modeling to predict the distribution of two poorly known small carnivore species that occur in Asia, the spotted linsang (Prionodon pardicolor) and banded linsang (Prionodon linsang), and analyzed their niche overlaps for habitat and elevation. We then assessed the loss of their suitable habitat and estimated the proportion of predicted presence under protected areas. We identified and assessed possible anthropogenic threats, and used our modeling predictions to recommend surveying priorities. Our study confirmed that these two linsangs are geographically separated, with no known overlap of their distributions. Our results indicated that the habitat and elevation niches of these two linsangs are similar: they both occur primarily in evergreen forest and can be found at all elevations up to around 3,000 m. Although these two linsangs might be allopatric due to intense interspecific competition between them, other explanations could explain their distribution patterns, such as biogeographical and ecological barriers. Our findings suggest that these two linsangs might be threatened by the loss, degradation, and fragmentation of tropical evergreen forests. Urgent field studies are thus needed to learn more about their habitat requirements and the impact of anthropogenic threats, including tropical forest disturbance and hunting.     

Habitat associations of parrots on the Wallacean islands of Buru, Seram and Sumba

Aim To investigate patterns of habitat use in nineteen populations of parrots on three Wallacean islands, and examine the degree to which habitats used by a species can be predicted across islands. Location The Wallacean islands on Buru, Seram and Sumba. Methods A logistic regression method was used to relate the presence/absence of parrot species at census plots to vegetation axes derived from ‘gross’ habitat parameters such as altitude, tree sizes, and percentages of vegetation coverage at different strata. Receiver Operating Characteristic Plots were then used to test predictions of habitat use by conspecific populations on the nearby and distant islands, and by different parrot species on the same island. Results Parrots on Buru and nearby Seram tended to be associated with open-canopied lowland forests, while on the distant and low-lying island of Sumba, the preference was for closed-canopy forests at higher altitudes. There were usually close affinities in habitat usage by conspecific populations on the two nearby islands. One exception was where the species occurred on the two islands as separate subspecies. Habitat preferences on Sumba, however, were so distinct that paradigms developed for Buru and Seram failed to predict distributions on this distant island. Main conclusions For populations on more distant islands, it will usually be better to predict habitat use by considering the habitat used by other parrot species occurring on that island, than a conspecific population from another region. Conservation research programmes which concentrate parrot study on just one or two islands in every region of Wallacea may be more successful than those which ‘run through’ several islands in a group, but which miss out whole regions.     

Characterisation of 13 microsatellite loci for the Moluccan Cockatoo, Cacatua moluccensis, and Cuban Amazon, Amazona leucocephala, and their conservation and utility in other parrot species (Psittaciformes)

The parrot family consists of approximately 330 species, many of which are endangered due to habitat destruction and illegal trade. Microsatellite markers can provide important tools for examining both conservation and forensic issues in this family, and the availability of additional markers will prove useful for studies of other species in the parrot family. Parrots have proved a difficult family from which to develop microsatellites and cross-species amplification is generally lower than expected. This paper details 13 microsatellite loci isolated from the Moluccan Cockatoo and Cuban Amazon and their conservation in other species of parrots.     

Protected areas and prime hoverfly areas: Safe haven for hoverflies or not?

The efficiency of protected areas (PAs) has often been questioned due to global decline of biodiversity. Invertebrates, especially insects, have been historically underrepresented in conservation studies. Our study focuses on hoverflies, an important group of insect pollinators and proven to be good bioindicators. Research was focused in Serbia, one of Europe's hotspots of hoverfly diversity, with a long tradition of hoverfly research, which provided sufficient information for achieving our aims: identifying areas of high hoverfly diversity, evaluating the efficiency of PAs and prime hoverfly areas (PHAs) in the conservation of hoverflies, determining how well they cover the distribution of hoverfly species, especially those of conservation concern, and testing the importance of the size of the area for conservation of hoverfly diversity. We applied weighting of the species to help stress the importance of species of conservation concern. The results indicated that PHAs cover the areas with high hoverfly diversity better than PA networks, especially when it comes to species of conservation concern. Generalized linear model results showed that the area size was a significant predictor of number of species in both PA and PHA. This indicates that area size is key when designating new areas important for conservation, but there are also other factors that need to be taken into account, such as habitat quality or suitability. Studies like this are useful in aiding designation of new areas important for conservation of certain species and in identifying sampling gaps, which could potentially aim future research in that direction.     

Integrating data‐deficient species in analyses of evolutionary history loss

There is an increasing interest in measuring loss of phylogenetic diversity and evolutionary distinctiveness which together depict the evolutionary history of conservation interest. Those losses are assessed through the evolutionary relationships between species and species threat status or extinction probabilities. Yet, available information is not always sufficient to quantify the threat status of species that are then classified as data deficient. Data‐deficient species are a crucial issue as they cause incomplete assessments of the loss of phylogenetic diversity and evolutionary distinctiveness. We aimed to explore the potential bias caused by data‐deficient species in estimating four widely used indices: HEDGE, EDGE, PDloss, and Expected PDloss. Second, we tested four different widely applicable and multitaxa imputation methods and their potential to minimize the bias for those four indices. Two methods are based on a best‐ vs. worst‐case extinction scenarios, one is based on the frequency distribution of threat status within a taxonomic group and one is based on correlates of extinction risks. We showed that data‐deficient species led to important bias in predictions of evolutionary history loss (especially high underestimation when they were removed). This issue was particularly important when data‐deficient species tended to be clustered in the tree of life. The imputation method based on correlates of extinction risks, especially geographic range size, had the best performance and enabled us to improve risk assessments. Solving threat status of DD species can fundamentally change our understanding of loss of phylogenetic diversity. We found that this loss could be substantially higher than previously found in amphibians, squamate reptiles, and carnivores. We also identified species that are of high priority for the conservation of evolutionary distinctiveness.     

Factors influencing the abundance of parrots and hornbills in pristine and disturbed forests on New Britain, PNG

We estimated densities of parrot and hornbill species in primary and selectively logged forest and forest gardens at two lowland sites on New Britain, PNG. We related differences in abundance to food and nest-site availability in the different habitats and determined whether nest-site availability might limit local breeding populations. Blue-eyed Cockatoo Cacatua ophthalmica and Blyth's Hornbill Rhyticeros plicatus were usually rarer in forest gardens than in primary forest, but both fared well in logged forest. Eclectus Parrot Eclectus roratus was more common in all human-altered forests than in primary forest, and Eastern Black-capped Lory Lorius hypoinochrous was reasonably common throughout but extremely abundant in forest gardens at one site. Parrots and hornbills were recorded eating fruits of 15 tree species and flowers of nine species. Densities of these fruiting and flowering trees were highest in logged forest and forest gardens, respectively, indicating the importance of these anthropogenic habitats as feeding grounds for the assemblage. Active nest cavities were found in large individuals of 12 tree species. Densities of potential nest cavities were highest in primary forest and lowest in forest gardens. At both sites, estimates of potential nest-site density were significantly lower than estimates of the density of pairs of all species of parrots and hornbills: there may be 10–20 parrot/hornbill individuals per nest-hole. Continuing forest alteration, whilst further reducing nest-site availability, may allow large populations of parrots and hornbills to persist due to increased availability of food in some anthropogenic habitats. However, current abundance of such bird species may be a poor correlate of future extinction risk as long-lived taxa may remain common for some period even when annual recruitment has declined to critically low levels.     

Cavity-nesting birds are limited by nesting habitat in Neotropical agricultural landscapes

Most studies comparing biodiversity between natural and human-modified landscapes focus on patterns in species occurrence or abundance, but do not consider how different habitat types meet species' breeding requirements. Organisms that use or nest in tree cavities may be especially threatened by habitat conversion due to the loss of their nesting sites. Although cavity-nesting bird diversity is highest in the tropics, little is known about how tropical birds use cavities, how agriculture affects their reproductive biology, and how effective nest boxes could be as a conservation strategy in tropical agriculture. Here, we explored how habitat conversion from tropical forests to pasture affects the abundance, nesting habitat availability, and nest success of cavity-nesting birds in Northwest Ecuador. We conducted bird surveys and measured natural cavity availability and use in forest and agriculture. We also added artificial nest boxes to forest and agriculture to see whether cavity limitation in agriculture would elicit higher use of artificial nest boxes. We found evidence of cavity limitation in agriculture—there were many more natural cavities in forest than in agriculture, as well as more avian use of nest boxes placed in agriculture as compared to forest. Our results suggest that it is important to retain remnant trees in tropical agriculture to provide critical nesting habitat for birds. In addition, adding nest boxes to tropical agricultural systems could be a good conservation strategy for certain species, including insectivores that could provide pest-control services to farmers. Abstract in Spanish is available with online material.     

Future hotspots of terrestrial mammal loss

Current levels of endangerment and historical trends of species and habitats are the main criteria used to direct conservation efforts globally. Estimates of future declines, which might indicate different priorities than past declines, have been limited by the lack of appropriate data and models. Given that much of conservation is about anticipating and responding to future threats, our inability to look forward at a global scale has been a major constraint on effective action. Here, we assess the geography and extent of projected future changes in suitable habitat for terrestrial mammals within their present ranges. We used a global earth-system model, IMAGE, coupled with fine-scale habitat suitability models and parametrized according to four global scenarios of human development. We identified the most affected countries by 2050 for each scenario, assuming that no additional conservation actions other than those described in the scenarios take place. We found that, with some exceptions, most of the countries with the largest predicted losses of suitable habitat for mammals are in Africa and the Americas. African and North American countries were also predicted to host the most species with large proportional global declines. Most of the countries we identified as future hotspots of terrestrial mammal loss have little or no overlap with the present global conservation priorities, thus confirming the need for forward-looking analyses in conservation priority setting. The expected growth in human populations and consumption in hotspots of future mammal loss mean that local conservation actions such as protected areas might not be sufficient to mitigate losses. Other policies, directed towards the root causes of biodiversity loss, are required, both in Africa and other parts of the world.     

De Brazza's monkeys (Cercopithecus neglectus) in Kenya: Census,distribution, and conservation

The population of De Brazza's monkeys (Cercopithecus neglectus) in Kenya, East Africa, was surveyed from May to September of 1983 to estimate its numbers, distribution, and conservation status. A small number of De Brazza's monkeys are protected within Saiwa National Park; however, the vast majority of the population is endangered because they are restricted to small, isolated pockets of forests amid expanding farmland within the Trans-Nzoia area of western Kenya. A few animals are found on the slopes of Mt. Elgon and on the Cherangani Hills, although these areas offer little protection. The pressures now facing this population are loss of habitat, reproductive isolation, and a decline in numbers as the result of being killed, either as a food source or as agricultural pests. If the current situation continues and no attempt is made to conserve the remaining De Brazza's monkeys, the species faces almost certain extinction in Kenya.     

海南岛淡水蟹类分布格局与多样性保护

热带岛屿生物多样性是全球生物多样性保护研究的热点之一。海南岛是中国面积最大的热带岛屿, 丰富独特的淡水蟹类是维持岛内淡水生态系统功能完整性的关键类群。本文通过多年野外调查, 综合历史及最新文献资料, 对海南岛淡水蟹类物种多样性及其现状进行调查和评估, 并对淡水蟹类物种多样性保护现状进行了分析讨论。研究发现, 海南岛淡水蟹类物种多样性分布中心位于中南部山地, 主要集中于中部的霸王岭、鹦哥岭和猕猴岭, 南部的五指山和吊罗山, 以及西南部的尖峰岭一带。其物种多样性整体上呈现中南部山地高、平原台地低的特点。根据《IUCN物种红色名录濒危等级和标准》对海南岛淡水蟹类物种现状的评估结果显示, 全岛受威胁淡水蟹类物种的占比为16.7%。基于分布区预测, 以海南热带雨林国家公园为主体的保护地对淡水蟹类潜在适宜分布区的覆盖度明显优于此前碎片化的各级保护区。本文研究结果显示, 海南岛淡水蟹类的总体生存状况良好, 但一部分山地或平原种类处于受胁状态。国家公园体制的建立有望为岛内淡水蟹类物种多样性保护提供前所未有的机遇。基于物种多样性分布格局开展淡水蟹类等淡水生物多样性监测, 有助于促进海南岛淡水生态系统完整性的长效保护与可持续发展。