Correlates of extinction proneness in tropical angiosperms

Rapid losses and degradation of natural habitats in the tropics are driving catastrophic declines and extinctions of native biotas, including angiosperms. Determining the ecological and life-history correlates of extinction proneness in tropical plant species may help reveal the mechanisms underlying their responses to habitat disturbance, and assist in the pre-emptive identification of species at risk from extinction. We determined the predictors of extinction proneness in 1884 locally extinct ( n  = 454) and extant ( n  = 1430) terrestrial angiosperms (belonging to 43 orders, 133 families, and 689 genera) in the tropical island nation of Singapore (699.4 km²), which has lost 99.6% of its primary lowland evergreen rainforest since 1819. A wide variety of traits such as geographical distribution, pollination system, sexual system, habit, habitat, height, fruit/seed dispersal mechanism, and capacity for vegetative re-sprouting were used in the analysis. Despite controlling for phylogeny (as approximated by family level classification), we found that only a small percentage of the variation in the extinction probability could be explained by these factors. Epiphytic, monoecious, and hermaphroditic species and those restricted to inland forests have higher probabilities of extinction. Species dependent on mammal pollinators also probably have higher extinction probabilities. More comparative studies that use species traits to identify extinction-prone plant species are needed to guide the enormous, but essential task of identifying species most in need of conservation action.     

An identification of invariants in life history traits of amphibians and reptiles

While many morphological, physiological, and ecological characteristics of organisms scale with body size, some do not change under size transformation. They are called invariant. A recent study recommended five criteria for identifying invariant traits. These are based on that a trait exhibits a unimodal central tendency and varies over a limited range with body mass (type I), or that it does not vary systematically with body mass (type II). We methodologically improved these criteria and then applied them to life history traits of amphibians, Anura, Caudata (eleven traits), and reptiles (eight traits). The numbers of invariant traits identified by criteria differed across amphibian orders and between amphibians and reptiles. Reproductive output (maximum number of reproductive events per year), incubation time, length of larval period, and metamorphosis size were type I and II invariant across amphibians. In both amphibian orders, reproductive output and metamorphosis size were type I and II invariant. In Anura, incubation time and length of larval period and in Caudata, incubation time were further type II invariant. In reptiles, however, only number of clutches per year was invariant (type II). All these differences could reflect that in reptiles body size and in amphibians, Anura, and Caudata metamorphosis (neotenic species go not through it) and the trend toward independence of egg and larval development from water additionally constrained life history evolution. We further demonstrate that all invariance criteria worked for amphibian and reptilian life history traits, although we corroborated some known and identified new limitations to their application.     

Edge effects and extinction proneness in a herpetofauna from Madagascar

Edge effects are thought to play a key role in fragmented habitats. It is often assumed that edge-avoiding species are more prone to local extinction than non-edge-avoiding species, but there are few data to support this assumption. Also, few data are available on the effects of edges on some groups, and there is little understanding of seasonal changes in edge effect intensity. To better understand the role that edge effects play in fragmented tropical forests, we assessed the distribution of reptiles and amphibians in six littoral rainforest fragments in southeastern Madagascar in 1999 (dry season) and 2000 (wet season). Using randomization tests, we found all three types of edge responses: edge-avoiders, interior-avoiders, and omnipresent species. However, edge responses varied considerably among seasons. For example, some species (e.g., Mantidactylus bicalcaratus, Phelsuma quadriocellata) were strong edge-avoiders in the dry season, but showed no preference for edge or interior habitats during the wet season. Also, edge-avoiding species tended to be more extinction-prone than non-edge-avoiding species. Abiotic data documented significantly higher temperatures and dew point temperatures near edges. Wind speed also tended to be higher and relative humidity tended to be lower near edges. Our results indicate that many amphibians and reptiles respond to altered microclimates near edges and these responses have a strong seasonal component. For many species, edge sensitivity does seem to be correlated with extinction vulnerability and therefore should be of primary consideration in plans to conserve biodiversity in fragmented tropical forests.     

Integrating species traits with extrinsic threats: closing the gap between predicting and preventing species declines

In studies of extinction risk, it is often insufficient to conclude that species with narrow ranges or small clutch sizes require prioritized protection. To improve conservation outcomes, we also need to know which threats interact with these traits to endanger some species but not others. In this study, we integrated the spatial patterns of key threats to Australian amphibians with species' ecological/life-history traits to both predict declining species and identify their likely threats. In addition to confirming the importance of previously identified traits (e.g. narrow range size), we find that extrinsic threats (primarily the disease chytridiomycosis and invasive mosquitofish) are equally important and interact with intrinsic traits (primarily ecological group) to create guild-specific pathways to decline in our model system. Integrating the spatial patterns of extrinsic threats in extinction risk analyses will improve our ability to detect and manage endangered species in the future, particularly where data deficiency is a problem.     

Species turnover of amphibians and reptiles in eastern China: disentangling the relative effects of geographic distance and environmental difference

Spatial turnover of species lies at the heart of macroecology and conservation biogeography. However, our knowledge of the causes of species turnover remains poor, particularly for herpetofaunas including amphibians and reptiles. Here, using regression, variance partitioning, and hierarchical partitioning analyses, we examine the relationships of species turnover in herpetofaunas among provinces in eastern China with respect to geographic distance and environmental difference. We found that species turnover in herpetofaunas is moderately to strongly correlated with geographic distance and difference in most environmental variables examined between provinces. Geographic distance and environmental difference together explain 87.1 and 89.9% of the variance of species turnover for amphibians and reptiles, respectively. Variance partitioning analysis indicated that most variance in species turnover is explained by the joint effect of geographic distance and environmental difference. Beyond this shared variance, environmental difference is a stronger predictor of species turnover than geographic distance, particularly for reptiles. Hierarchical partitioning analysis showed that energy-related variables explained more variance in species turnover for both amphibians and reptiles, compared with water-related variables. The independent effects of water-related variables are slightly higher for amphibians than for reptiles whereas the independent effects of energy-related variables are slightly higher for reptiles than amphibians. These patterns are consistent with different ecophysiological requirements of the two taxa. Our results have important implications for predicting changes in biodiversity of herpetofaunas under climate change scenarios. Global warming will affect the immigration and local extinction of both amphibians and reptiles, and precipitation change may affect amphibians more strongly, compared with its effect on reptiles.     

Nested communities,invasive species and Holocene extinctions: evaluating the power of a potential conservation tool

General ecological methods and models that require a minimum amount of information yet are still able to inform conservation planning are particularly valuable. Nested subset analysis has been advocated as such a tool for the prediction of extinction-prone species and populations. However, such advocacy has not been without skepticism and debate, and in the majority of published examples assessing extinction vulnerability, actual extinctions are based on assumptions rather than direct evidence. Here, we empirically test the power of nested subset analysis to predict extinction-prone species, using documented Holocene insular mammal extinctions on three island archipelagos off the west coast of North America. We go on to test whether the introduction of invasive mammals promotes nestedness on islands via extinction. While all three archipelagos were significantly nested before and after the extinction events, nested subset analysis largely failed to predict extinction patterns. We also failed to detect any correlations between the degree of nestedness at the genus-level with area, isolation, or species richness and extinction risk. Biogeography tools, such as nested subset analysis, must be critically evaluated before they are prescribed widely for conservation planning. For these island archipelagos, it appears detailed natural history and taxa-specific ecology may prove critical in predicting patterns of extinction risk.     

Reptiles as potential vectors and hosts of the amphibian pathogen Batrachochytrium dendrobatidis in Panama

Chytridiomycosis, the disease caused by Batrachochytrium dendrobatidis, is considered to be a disease exclusively of amphibians. However, B. dendrobatidis may also be capable of persisting in the environment, and non-amphibian vectors or hosts may contribute to disease transmission. Reptiles living in close proximity to amphibians and sharing similar ecological traits could serve as vectors or reservoir hosts for B. dendrobatidis, harbouring the organism on their skin without succumbing to disease. We surveyed for the presence of B. dendrobatidis DNA among 211 lizards and 8 snakes at 8 sites at varying elevations in Panama where the syntopic amphibians were at pre-epizootic, epizootic or post-epizootic stages of chytridiomycosis. Detection of B. dendrobatidis DNA was done using qPCR analysis. Evidence of the amphibian pathogen was present at varying intensities in 29 of 79 examined Anolis humilis lizards (32%) and 9 of 101 A. lionotus lizards (9%), and in one individual each of the snakes Pliocercus euryzonus, Imantodes cenchoa, and Nothopsis rugosus. In general, B. dendrobatidis DNA prevalence among reptiles was positively correlated with the infection prevalence among co-occurring anuran amphibians at any particular site (r = 0.88, p = 0.004). These reptiles, therefore, may likely be vectors or reservoir hosts for B. dendrobatidis and could serve as disease transmission agents. Although there is no evidence of B. dendrobatidis disease-induced declines in reptiles, cases of coincidence of reptile and amphibian declines suggest this potentiality. Our study is the first to provide evidence of non-amphibian carriers for B. dendrobatidis in a natural Neotropical environment.     

从自然保护区到国家公园体制试点: 三江源国家公园环境覆盖的变化及其对两栖爬行类保护的启示

三江源地区具有丰富的高原生物多样性, 是我国重要的生态安全屏障。作为我国第一个体制试点的国家公园, 三江源国家公园将被建成青藏高原大自然保护展示和生态文化传承区。为更好地服务于三江源国家公园建设, 本研究从海拔、年均温和年降水等方面, 在环境空间上系统比较了国家公园与三江源和可可西里自然保护区的差异; 以4种两栖爬行动物即高原林蛙(Rana kukunoris)、倭蛙(Nanorana pleskei)、西藏齿突蟾(Scutiger boulengeri)和青海沙蜥(Phrynocephalus vlangalii)分布点环境条件在国家公园内外的异同为例, 探讨分布受环境制约大、扩散能力弱的物种保护在国家公园建设中可能面临的机遇和挑战。结果表明, 国家公园与已建自然保护区在地理空间上重叠较大, 但它们在自然环境上的差别很明显; 自然保护区内两栖爬行类所偏好的环境条件较多未包含在国家公园内。鉴于三江源的区位特殊性及对气候变化的敏感性, 区域内两栖爬行动物等对环境依赖性强、扩散能力弱物种的有效保护不仅有助于保持物种遗传多样性和区域生态系统的完整性, 也有利于更好地实现国家公园目标定位并服务于生态文明建设。为此, 在国家公园内, 应开展两栖爬行动物种群动态和群落结构的长期监测, 加强基础生物学研究, 掌握环境变化对两栖爬行动物分布、遗传、行为、形态、种群动态及群落可能产生的影响, 实现区域内两栖爬行动物及其类似物种在环境变化下的永续生存。     

Patterns of richness and endemism of the Mexican herpetofauna,a matter of spatial scale?

The goal of this study was to compare the richness and endemism patterns of Mexican species of amphibians and reptiles at different spatial scales. We used the best available dataset of distributional ranges generated from ecological niche models and employed geographically weighted regressions (GWRs) to test whether richness and endemism were related. Patterns were found to vary with the scale used for richness and endemism, and these patterns were not coincident. The results showed that: (1) only relatively coarse spatial scales can address latitudinal patterns in amphibians and reptiles, and, in fine scales, they are related to topographic formations; (2) areas of greatest endemism for amphibians and reptiles are located in the highlands of the central or southern part of the country, although not necessarily in the same specific highlands for both groups; (3) there is a strong average correlation between richness and endemism for both groups, indicating that the same factors contribute to both patterns, but these factors act differentially in terms of regions among amphibians and reptiles; and (4) the scale at which the analysis is conducted is important, and we believe that careful consideration of spatial scale must be undertaken to avoid false conclusions. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 305–316.     

Circadian Rhythms in Amphibians and Reptiles: Ecological Implications

Circadian rhythms of amphibians and reptiles in the field and under semi-natural conditions and the underlying mechanisms, including the ways of entrainment to environmental cues and the oscillators driving the rhythms, have been reviewed. Studies on the behavioral rhythms in the field are meager in both amphibians and reptiles. In anuran amphibians, Xenopus adults showed more robust nocturnal locomotor activity than did tadpoles. This indicates the ecological significance of the differences in activity pattern shown by amphibians at different life stages, because differences between adults and young in the same environment may serve to isolate partially the young from the adults' cannibalism. In reptiles, free-running rhythms are more robust and continue for a longer time compared to amphibians. In both amphibians and reptiles, multi-photoreceptors are involved in photo-entrainment of circadian rhythms. The eyes, pineal complex and deep brain comprise a multi-oscillator system as well as a multi-photoreceptor system.     

四川省喇叭河自然保护区的两栖爬行动物初步调查

喇叭河自然保护区共有两栖动物2月7科22种,区系组成以东洋界西南区为主;爬行动物1目7科17种,区系组成以东洋界广布种为主。两栖爬行动物是保护区内的重要资源。喇叭河自然保护区是保护横断山东缘物种多样性的关键地区之一。     

江西武功山两栖爬行动物资源调查及评价

2001年7月中旬～8月上旬,对江西武功山国家森林公园进行了20多天的野生动植物资源野外考察.公园内现已记录两栖类2目7科25种和爬行类3目9科37种,本次调查增加安福县爬行动物新记录7种：多疣壁虎、中国石龙子、黑背白环蛇、铅色水蛇、灰鼠蛇、乌梢蛇、银环蛇;增加武功山爬行动物新记录23种.动物地理区划属东洋界华中区东部丘陵平原亚区,动物区系组成以东洋界华中区与华南区共有种为主.两栖类东洋界种类占92.00%;生态类型以流水型9种和陆栖-静水型7种占优势.数量优势种为黑斑蛙、中华蟾蜍、黑斑肥螈、泽蛙、棘胸蛙、花臭蛙、华南湍蛙、三港树蟾、镇海林蛙和饰纹姬蛙.爬行类东洋界种类占75.68%,广布种占24.32%.数量优势种有石龙子、蓝尾石龙子、铜蜓蜥、赤链华游蛇、王锦蛇、虎斑颈槽蛇、赤链蛇、红点锦蛇、乌梢蛇、灰鼠蛇、尖吻蝮、竹叶青蛇等.公园内野生动物及其生境受人类干扰破坏大,当地群众保护意识有待增强,就此提出了保护对策.     

Risk assessment of potential invasiveness of exotic reptiles imported to south Florida

The recent explosion of exotic reptiles in south Florida requires effective management strategies. The objective of this study is to bring knowledge of ecological correlates and quantitative modeling methods into management by providing the foundation for a screening procedure that will identify potentially invasive species and assess adverse impacts associated with these species. We considered 17 variables and, based on model selection procedures, we identified the following significant predictors of establishment success: taxonomic order, maximum temperature match between a species’ native range and Florida, animal sale price, and manageability (defined as a species’ maintenance cost, aggressiveness, proneness to escape, and venomousness). Applying the models to predict establishment success of 33 reptiles that were most frequently imported through Miami and St. Petersburg ports from 2000 to 2005 and two additional reptiles of concern in Florida, we identified eight lizards and four snakes as potentially successful invaders. We further assessed adverse impacts associated with potential invaders, should they become established, by identifying species that are (1) dangerous to humans, (2) dangerous to the ecosystem (upper trophic-level predators), and (3) rapidly spreading. Controlling exotic reptiles can be expensive and labor intensive once they are established. Information on which species are potential invaders based on screening procedures and what impacts these species might cause will be a valuable contribution to the development of proactive management strategies.     

Opportunistic records reveal Mediterranean reptiles’ scale‐dependent responses to anthropogenic land use

Although classified among the greatest threats to the world's biodiversity, the effects of land use and their scale dependency are left unexplored in many taxonomic groups. Reptiles are among the most data‐deficient vertebrates in this respect, although their ecological traits make them highly sensitive to habitat modifications. We tested whether land use gradients shape the distributions of Mediterranean reptiles at regional and local scales, and whether species’ ecological traits and phylogeny explain these patterns. Reptiles are generally rare and hard to survey through standardized protocols. We overcame these obstacles by modeling an original data set of 18164 opportunistic occurrence records for 14 reptile species with spatially‐explicit point process models incorporating known sources of sampling heterogeneity and spatially autocorrelated error. At a regional scale, reptiles favored open habitats and tended to avoid urban areas. At a local scale, the persistence of open habitats did better than forest resulting from land abandonment in maintaining reptiles within a heavily anthropogenic matrix. Contrary to our expectations, the absence of any clear trait or phylogenetic signals suggests that these responses are mediated by a complex interplay between species’ ecology and regional biogeographic history. These results demonstrate that reptile responses to land use are scale‐dependent and locally exacerbated when anthropogenic pressure is high. We further show that land abandonment is insufficient to preserve reptiles in the face of anthropogenic pressures unless patches of suitable habitat are effectively maintained. Eventually, our study further illustrates the effectiveness of volunteer‐based opportunistic sampling in testing hypotheses on the determinants of rare species’ distributions.     

Extinction Risks and the Conservation of Madagascar's Reptiles

Background

An understanding of the conservation status of Madagascar''s endemic reptile species is needed to underpin conservation planning and priority setting in this global biodiversity hotspot, and to complement existing information on the island''s mammals, birds and amphibians. We report here on the first systematic assessment of the extinction risk of endemic and native non-marine Malagasy snakes, lizards, turtles and tortoises.

Methodology/Principal Findings

Species range maps from The IUCN Red List of Threatened Species were analysed to determine patterns in the distribution of threatened reptile species. These data, in addition to information on threats, were used to identify priority areas and actions for conservation. Thirty-nine percent of the data-sufficient Malagasy reptiles in our analyses are threatened with extinction. Areas in the north, west and south-east were identified as having more threatened species than expected and are therefore conservation priorities. Habitat degradation caused by wood harvesting and non-timber crops was the most pervasive threat. The direct removal of reptiles for international trade and human consumption threatened relatively few species, but were the primary threats for tortoises. Nine threatened reptile species are endemic to recently created protected areas.

Conclusions/Significance

With a few alarming exceptions, the threatened endemic reptiles of Madagascar occur within the national network of protected areas, including some taxa that are only found in new protected areas. Threats to these species, however, operate inside and outside protected area boundaries. This analysis has identified priority sites for reptile conservation and completes the conservation assessment of terrestrial vertebrates in Madagascar which will facilitate conservation planning, monitoring and wise-decision making. In sharp contrast with the amphibians, there is significant reptile diversity and regional endemism in the southern and western regions of Madagascar and this study highlights the importance of these arid regions to conserving the island''s biodiversity.     

Can a large metropolis sustain complex herpetofauna communities? An analysis of the suitability of green space fragments in Rome

Urban areas are primary causes of species' range fragmentation and reduction. However, relatively few studies have attempted to describe the habitat variables influencing the diversity and conservation of amphibians and reptiles, particularly in Mediterranean Europe and in large metropolitan areas. We explored this broad conservation ecology problem by studying the richness and diversity patterns in relation to a suite of six independent habitat variables in Rome, one of the most ancient cities of the world. We considered all the green remnant areas ( n =62) of Rome, ranging 1 to >1000 ha in size, which are interspersed within a sea of urbanized matrix. A total of 10 amphibian and 15 reptile species were studied. Their presence/absence patterns were assessed and the effects of the various habitat variables on each species were predicted by a logistic regression model. A total of 1261 presence records (404 amphibians and 857 reptiles) were analysed. Fragment size and wood size within each fragment did correlate significantly with the species richness of both amphibians and reptiles, and there was a clear threshold effect after 50 ha of wooded surface. The presence of water bodies positively affected the species distribution. One amphibian and three reptiles inhabited exclusively fragments >50 ha. The distance from the centre did not affect fragment species richness. The presence of most species of both amphibians and reptiles was positively influenced by the irregular versus circular shape of the wooded area. The legal protection of a given area did not influence the observed patterns but the total number of sheltered species. Overall, our study suggests that, in order to maintain the current diversity and population viability, it is necessary, in addition to water bodies' maintenance, to (1) preserve the wooded landscapes over 50 ha; (2) promote irregularly shaped increases in the wood surface; (3) maintain ecotonal boundaries.     

Methodologies for the care,maintenance, and breeding of tropical poison frogs

The Biodiversity Laboratories at Saint Joseph's University house more than 100 exotic and endangered animal species-including insects, fish, amphibians, and reptiles. Research in the laboratories is devoted, primarily, to understanding the genetic and ecological bases of animal behavior. In addition, a common theme of the work is the development of techniques for the successful care of exotic animals within a laboratory setting. Such techniques may be critical to studies aimed at understanding the life histories of endangered species and saving them from extinction. Current projects to study the biology of tropical poison frogs have methodologies to improve captive care, maintenance, and breeding. In this article, I present these methodologies and their impact on the welfare of captive poison frogs.     

Distribution, ecology, life history, genetic variation, and risk of extinction of nonhuman primates from Costa Rica

We examined the association between geographic distribution, ecological traits, life history, genetic diversity, and risk of extinction in nonhuman primate species from Costa Rica. All of the current nonhuman primate species from Costa Rica are included in the study; spider monkeys (Ateles geoffroyi), howling monkeys (Alouatta palliata), capuchins (Cebus capucinus), and squirrel monkeys (Saimiri oerstedii). Geographic distribution was characterized accessing existing databases. Data on ecology and life history traits were obtained through a literature review. Genetic diversity was characterized using isozyme electrophoresis. Risk of extinction was assessed from the literature. We found that species differed in all these traits. Using these data, we conducted a Pearson correlation between risk of extinction and ecological and life history traits, and genetic variation, for widely distributed species. We found a negative association between risk of extinction and population birth and growth rates; indicating that slower reproducing species had a greater risk of extinction. We found a positive association between genetic variation and risk of extinction; i.e., species showing higher genetic variation had a greater risk of extinction. The relevance of these traits for conservation efforts is discussed.     

广西涠洲岛鸟类自然保护区的两栖爬行动物

2008年5～6月对广西涠洲岛鸟类自然保护区的两栖爬行动物进行调查,共记录到两栖类7种,爬行类16种,隶属于3目11科.与18年前的调查结果对比,生境的变化使岛上两栖爬行动物的分布范围和多度发生一些改变.2008年初的冰冻灾害使涠洲岛的两栖爬行类损失较大.涠洲岛与邻近大陆的两栖爬行动物物种相似,无特有种.