Predicting establishment success for alien reptiles and amphibians: a role for climate matching

We examined data comprising 1,028 successful and 967 failed introduction records for 596 species of alien reptiles and amphibians around the world to test for factors influencing establishment success. We found significant variations between families and between genera. The number of jurisdictions where a species was introduced was a significant predictor of the probability the species had established in at least one jurisdiction. All species that had been introduced to more than 10 jurisdictions (34 species) had established at least one alien population. We also conducted more detailed quantitative comparisons for successful (69 species) and failed (116 species) introductions to three jurisdictions (Great Britain, California and Florida) to test for associations with climate match, geographic range size, and history of establishment success elsewhere. Relative to failed species, successful species had better climate matches between the jurisdiction where they were introduced and their geographic range elsewhere in the world. Successful species were also more likely to have high establishment success rates elsewhere in the world. Cross-validations indicated our full model correctly categorized establishment success with 78–80% accuracy. Our findings may guide risk assessments for the import of live alien reptiles and amphibians to reduce the rate new species establish in the wild.     

Fast life history traits promote invasion success in amphibians and reptiles

Competing theoretical models make different predictions on which life history strategies facilitate growth of small populations. While ‘fast’ strategies allow for rapid increase in population size and limit vulnerability to stochastic events, ‘slow’ strategies and bet‐hedging may reduce variance in vital rates in response to stochasticity. We test these predictions using biological invasions since founder alien populations start small, compiling the largest dataset yet of global herpetological introductions and life history traits. Using state‐of‐the‐art phylogenetic comparative methods, we show that successful invaders have fast traits, such as large and frequent clutches, at both establishment and spread stages. These results, together with recent findings in mammals and plants, support ‘fast advantage’ models and the importance of high potential population growth rate. Conversely, successful alien birds are bet‐hedgers. We propose that transient population dynamics and differences in longevity and behavioural flexibility can help reconcile apparently contrasting results across terrestrial vertebrate classes.     

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.     

Habitat alteration increases invasive fire ant abundance to the detriment of amphibians and reptiles

Altered habitats have been suggested to facilitate red imported fire ant (Solenopsis invicta) colonization and dispersal, possibly compounding effects of habitat alteration on native wildlife. In this study, we compared colonization intensity of wood cover boards by S. invicta among four forest management treatments in South Carolina, USA: an unharvested control (>30 years old); a partially thinned stand; a clearcut with coarse woody debris retained; and a clearcut with coarse woody debris removed. Additionally, we compared dehydration rates and survival of recently metamorphosed salamanders (marbled salamanders, Ambystoma opacum, and mole salamanders, A. talpoideum) among treatments. We found that the number of wood cover boards colonized by S. invicta differed significantly among treatments, being lowest in the unharvested forest treatments and increasing with the degree of habitat alteration. Salamanders that were maintained in experimental field enclosures to study water loss were unexpectedly subjected to high levels of S. invicta predation that differed among forest treatments. All known predation by S. invicta was restricted to salamanders in clearcuts. The amount of vegetative ground cover was inversely related to the likelihood of S. invicta predation of salamanders. Our results show that S. invicta abundance increases with habitat disturbance and that this increased abundance has negative consequences for amphibians that remain in altered habitats. Our findings also suggest that the presence of invasive S. invicta may compromise the utility of cover boards and other techniques commonly used in herpetological studies in the Southeast.     

Comparative phylogeography of West African amphibians and reptiles

Comparative phylogeographic studies often support shared divergence times for co-distributed species with similar life histories and habitat specializations. During the late Holocene, West Africa experienced aridification and the turnover of rain forest habitats into savannas. These fragmented rain forests harbor impressive numbers of endemic and threatened species. In this setting, populations of co-distributed rain forest species are expected to have diverged simultaneously, whereas divergence events for species adapted to savanna and forest-edge habitats should be absent or idiosyncratic. We conducted a Bayesian analysis of shared evolutionary events to test models of population divergence for 20 species of anurans (frogs) and squamates (lizards and snakes) that are distributed across the Dahomey Gap, a climate change-induced savanna barrier responsible for fragmenting previously contiguous rain forests of Ghana into two regions: the Togo-Volta Hills and the Southwestern Forests. A model of asynchronous diversification is supported for anurans and squamates, suggesting that drivers of diversification are not specifically related to ecological and life history associations with habitat types. Instead, the wide variability of genetic divergence histories exhibited by these species suggests that biodiversity in this region has been shaped by diversification events that extend beyond the Holocene. Comparisons of the genealogical divergence index, a measure of the genetic divergence between populations due to the combined effects of genetic isolation and gene flow, illustrate that these populations represent a broad sampling of the speciation continuum.     

中国两栖、爬行动物更新名录

本文在2015年发表的爬行动物名录及同年《中国两栖类信息系统》发布的两栖动物名录的基础上, 通过整理新发表的分类学研究及先前名录遗漏的部分早期文献, 更新了截至2019年底中国现生本土两栖、爬行动物物种名录。2015-2019年间, 中国两栖动物新记录1科, 新描述2属, 恢复1属有效性, 新记录1属, 新描述或恢复有效种74种, 新增国家纪录18种; 另6属、8种的有效性未得到近年研究证据支持(在此视为次定同物异名而未做收录, 后同)。同期, 中国爬行动物新恢复5科, 新描述1亚科, 新描述1属, 恢复3属有效性, 新记录3属, 新描述、恢复或提升有效种43个, 新增国家纪录10种; 另有5属、4种的有效性未得到近年研究证据支持, 并移除1属、4种在我国的分布纪录。此外, 通过整理2015年前文献, 爬行动物增补3属, 提升3亚种至种级地位, 增补国家新纪录3种, 另有3属、2种的有效性未得到近年研究证据支持, 同时移除1种在我国的分布纪录。综上, 截至2019年底, 我国共记录现生本土两栖动物3目13科62属515种(蚓螈目1科1属1种, 有尾目3科14属82种, 无尾目9科47属431种), 爬行动物3目35科135属511种(鳄形目1科1属1种, 龟鳖目6科18属34种, 有鳞目蛇亚目18科73属265种、蜥蜴亚目10科43属211种)。此外, 本文还对先前名录中部分爬行动物的中文名提出了修改建议, 建议恢复部分物种的惯用中文名。2015-2019年, 新物种及新纪录已知物种数量占现两栖、爬行动物物种总数的17.1%和10.2%。近年来, 我国发表的两栖、爬行动物新物种和已知物种的新纪录数量持续增加, 分类体系也在研究中不断完善, 建议今后及时地进行阶段性总结, 同时对存在的问题提出讨论, 以推动中国两栖、爬行动物分类学研究工作的进一步开展。     

The respiratory consequences of feeding in amphibians and reptiles

Many ectothermic vertebrates ingest very large meals at infrequent intervals. The digestive processes associated with these meals, often coupled with an extensive hypertrophy of the gastrointestinal organs, are energetically expensive and metabolic rate, therefore, increases substantially after feeding (specific dynamic action, SDA). Here, we review the cardio-respiratory consequences of SDA in amphibians and reptiles. For some snakes, the increased oxygen uptake during SDA is of similar magnitude to that of muscular exercise, and the two physiological states, therefore, exert similar and profound demands on oxygen transport by the cardiorespiratory systems. In several species, SDA is attended by increases in heart rate and overall systemic blood flows, but changes in blood flow distribution remain to be investigated. In snakes, the regulation of heart rate appears to involve a non-adrenergic-non-cholinergic mechanism, which may be a regulatory peptide released from the gastrointestinal system during digestion. Digestion is also associated with a net acid secretion to the stomach that causes an increase in plasma HCO3- concentration (the 'alkaline tide'). Experiments on chronically cannulated amphibians and reptiles, show that this metabolic alkalosis is countered by an increased P(CO2), so that the change in arterial pH is reduced. This respiratory compensation of arterial pH is accomplished through a reduction in ventilation relative to metabolism, but the estimated reductions in lung P(O2) are relatively small. The SDA response is also associated with haematological changes, but large interspecific differences exist. The studies on cardiorespiratory responses to digestion may allow for a further understanding of the physiological and structural constraints that limits the ability of reptiles and amphibians to sustain high metabolic rates.     

Ascaridoid nematodes of amphibians and reptiles: Ophidascaris Baylis, 1920

The genus Ophidascaris is revised and divided into five groups of species. A key for the species groups is provided. Group 1 (‘filaria’ group) occurs in pythons and a key is provided for differentiating eight species based on fresh and preserved specimens and on developmental patterns. O. papillifera (Linstow, 1898) is redescribed from the type-specimens and is considered to be close or identical to O. niuginiensis, for which Candoia carinatus is recorded as a new host. A key for the differentiation of species in Groups 2 to 5 is based on preserved specimens only. Group 2 (‘obconica’ group) contains (i) O. obconica and O. trichuriformis [= caballeroi] in South American colubrids (further investigation will probably show that O. trichuriformis is a synonym of O. obconica); new host records are Xenodon severus, X. neuwiedii, X. colubrinus, Leptodeira annulata, Thamnodynastes pallidus, Leimadophis poecilogyrus and Boa constrictor; (ii) O. ashi n. sp. (new species name for ‘O. labiatopapillosa’) in North American colubrids, new host records are Nerodia valida, Heterodon nasicus and Storeria occipitomaculata; (iii) O. mombasica in African colubrids; new host records are Psammophis phillipsii and P. sibilans; (iv) O. solenopoion in Madagascan colubrids; (v) O. pyrrhus in Australian elapids; new host records are Cacophis squamulosus, Cryptophis nigrescens, Demansia atra, D. olivacea, Hemiaspis signata, Hoplocephalus bitorquatus, H. stephensi, H. bungaroides and Tropedechis carinatus, it is also recorded in Australia in the colubrid Styporhyncus mairii (new host record) and in Demansia papuensis papuensis and D. olivacea papuensis in Papua New Guinea; (vi) O. piscatori in Asian colubrids; (vii) O. excavata [? = schikhobalovi] in Agkistrodon spp. and possibly other aquatic snakes in Asia; new host record is Agkistrodon halys blomhoffi. Group 3 (‘radiosa’ group) in African viperids contains O. radiosa [ = intorta] in Bitis spp. Specimens from Atheris nitschei, Causus rhombeatus and the colubrid Boaedon lineatus were similar, but showed differences indicating possibility of other species in this group. Group 4 (‘najae’ group) in African elapids and Asian elapids and colubrids contains O. najae [ = daubaylisi]; new host records are Ophiophagus hannah, Boiga cyanea, Elaphe carinata. Group 5 (‘arndti’ group) in South American crotalids and colubrids contains O. arndti [ = travassosi and sprenti] in Crotalus spp. and Bothrops spp.; new host record is B. atrox in Panama. No morphological differentiation except size could be detected between O. arndti in crotalines and O. sicki in colubrids, but in view of difference in the feeding habits of their host, both species names were tentatively sustained; new host records for O. sicki are Xenodon neuwiedii, Leimadophis poecilogyrus, Pseudoboa cloelia, Philodryas patagoniensis and Micrurus frontalis; O. ochoteranai was regarded as a species inquirenda. The following species previously placed in Amplicaecum are placed in Ophidascaris; excavata Hsu & Hoeppli, 1931; schikhobalovi Mozgovoy, 1950; robertsi Sprent & Mines, 1960; longispiculum Oshmarin & Demshin, 1972; orientalis Wang, 1965. The position of Ophidascaris in relation to other ascaridoids is discussed: it is placed within the subfamily Ascaridinae sensu Sprent (1983) containing all other ascaridoids of terrestrial animals. It is concluded that Ophidascaris is in a relatively recent stage of evolution. The most likely centre of dispersal for the genus appears to have been Central Africa with spread in one direction to Asia and thence to the New World and in another direction to Madagascar and Australia.     

Aquatic pollution increases the relative success of invasive species

Although individual ecosystems vary greatly in the degree to which they have been invaded by exotic species, it has remained difficult to isolate mechanisms influencing invader success. One largely anecdotal observation is that polluted or degraded areas will accumulate more invaders than less-impacted sites. However, the role of abiotic factors alone in influencing invisibility has been difficult to isolate, often because the supply of potential invaders is confounded with conditions thought to increase vulnerability to invasion. Here, we conducted a field experiment to test how the assemblages of exotic versus native marine invertebrates changed during community assembly under different exposure levels of a common pollutant, copper. The experiment was conducted by deploying fouling panels in a Randomized Block Design in San Francisco Bay. Panels were periodically removed, placed into buckets with differing copper concentrations, and returned to the field after 3 days. This design allowed propagule availability to the plates to be statistically independent of short-term copper exposure. The results demonstrate that copper caused significant differences in community structure. Average native species richness was significantly affected by copper exposure, but average exotic richness was not. The total native species pool within treatments exhibited a greater than 40% decline within increasing copper, while the exotic species pool did not change significantly. These results confirm that anthropogenic alteration of abiotic factors influences invader success, indicating that management strategies to reduce invader impacts should include both efforts to improve environmental conditions as well as reduce invader supply.     

Spread of hemoparasites in reptiles and amphibians in Italy

Hemoparasites were harvested from 993 individuals belonging to 15 reptilian and 1 amphibian species, from various Italian localities. Hemogregarins were found in 10 reptilian species while a flagellate and microfilariae were found only in Tarentola mauritanica from Lampedusa. For each host species and place of origin the frequencies of hemogregarins are reported and discussed. Longitudinal studies with periodical thin smears were carried out on 5 Tarentola mauritanica, 4 Lacerta viridis, 26 Podarcis filfolensis, 10 Podarcis muralis, 38 Podarcis sicula, 8 Chalcides ocellatus. This material, whose study has not yet been completed, is made available by the author who strongly encourages further investigations on this subject.     

Nested species subsets of amphibians and reptiles on Neotropical forest islands

Nested species subsets are a common pattern of community assembly characteristic of many types of fragmented landscapes and insular systems. Here we describe nested subset patterns of amphibian and reptile occupancy on 23 forest islands in north-eastern Bolivia. We used observed occupancy patterns to differentiate five distributional guilds: widespread species, rare species, poor colonizers, area-sensitive species and supertramps. Amphibian occurrences were nested along a forest island isolation gradient, and when species from each of the distribution classes were removed from subsequent analyses of nestedness, we found that dispersal-limited poor colonizers were responsible for the association between nestedness and isolation. Amphibians associated with the grassland matrix at the study site showed a nested pattern linked with area, although this pattern did not scale up to all amphibians and could not be unequivocally attributed to any of the distributional guilds we recognized. There were no strong associations between two biological characteristics, body size and relative abundance in the matrix, and the likelihood of occupancy along either forest island area or isolation gradients. The relative importance of isolation in shaping nested patterns of amphibians on these forest islands may be a result of either (1) the greater range in isolation values included in this study compared with many others; (2) the long time since isolation in this landscape, manifesting a footprint of isolation not apparent in more recently fragmented patches; (3) the relatively homogeneous grassland matrix surrounding forest islands that likely provides little refuge for animals moving among forest islands.     

Impacts of climate change on the amphibians and reptiles of Southeast Asia

Amphibians and reptiles will be adversely affected by projected rapid changes in climate in the next decades. Here, we review the known and potential impacts of climate change on the Southeast Asian amphibians and reptiles and make mitigation recommendations for both research and policy. Current amphibian and reptile distributions and ecologies mirror climate patterns, and we expect that adaptation to changes in these parameters will be too slow relative to their rate of expected change, and that pervasive changes will occur to species assemblages, communities, and ecosystem functioning and services. Southest Asia is a network of islands with relatively few mountains, effectively preventing most herpetofauna from migrating away from the effects of climate change. Reflecting specific known and hypothesized physiological and ecological thresholds, we estimate that in <50 years, amphibians and reptiles in Southeast Asia will have reached or exceeded most limits in their abilities to adapt to the effects of climate change and that temperature dependent sex determination, higher metabolic rates, and less bio-available water will have severe and irreversible effects on these organisms. We suggest that human decision-making and policy development have already lagged and that societal change is happening too slowly for effective mitigation. If we are to avert devastating loss of biodiversity and a complete meltdown of ecosystem services, we must quickly change our attitudes and thinking about how we interact with and use biological systems.     

The effects of species properties and community context on establishment success

Understanding whether factors important for species establishment in a local community are predictable or context‐ dependent is key for determining the features that affect community stability and species coexistence. A major challenge for scientists addressing this question is that natural systems are complex. This makes it difficult to test multiple properties of species and features of the resident community simultaneously to determine what factors are most important for establishment success of a species into a novel community. We used the model aquatic system inside the leaves of the pitcher plant Sarracenia purpurea to test whether properties predicted to be important for establishment success of a species (initial density, competitive ability, body size) are generalizable across communities varying in resource availability and the presence of a top predator. For intermediate trophic‐level species, we found that both competitive dominance and initial density were important for establishment success. Although a less competitive species was also able to successfully establish in the communities, high resource availability and high initial density were important for its establishment success. Body size of the introduced species, although correlated with competitive ability, was not an important characteristic for establishment success. The presence of a top predator significantly decreased the densities of the introduced species when resources were low, but did not completely inhibit establishment success. The relative importance of each of these factors, and interactions among them, could not have been discerned through single hypothesis testing. The results from this work show the need for detailed experiments that focus on combinations of factors to understand if mechanisms determining community assembly and species establishment can be generalized across systems.     

Current status of the threatened amphibians and reptiles of Japan

This article compares amphibian and reptile components of the original and revised versions of the Red List of Japan, and analyzes geographic patterns of, and major threats to, species and subspecies now assigned to the threatened categories. The numbers of both amphibians and reptiles categorized as threatened in the Red List of Japan have increased greatly through its revision as a result of recent progress in the taxonomy of these groups in Japan, the introduction of new criteria for risk assessment, and unexpectedly rapid declines in the status of several taxa. Threatened taxa of amphibians and reptiles in the revised list tend to be concentrated in the Ryukyu Archipelago, where deforestation seems to be the major ultimate cause of declines. Reduction in the quality and quantity of inland water environments seems to be the major cause of declines in several endemic amphibians from the main islands of Japan. The importance of conservation was emphasized in the revised list by progress in taxonomy, by new insights and data on the estimation of temporal dynamics of population density or habitat size for threatened taxa, and by the impacts of and need to prevent further deforestation in the Ryukyus and of the ongoing destruction of inland water habitats on the main islands of Japan. Received: May 6, 1999 / Accepted: October 26, 1999     

The behavioral responses of amphibians and reptiles to microgravity on parabolic flights

In the present study, we exposed 53 animals from 23 different species of amphibians and reptiles to microgravity (mug). This nearly doubles the number of amphibians and reptiles observed so far in mug. The animals were flown on a parabolic flight, which provided 20-25s of mug, to better characterize behavioral reactions to abrupt exposure to mug. Highly fossorial limbless caecilians and amphisbaenians showed relatively limited movement in mug. Limbed quadrupedal reptiles that were non-arboreal in the genera Leiocephalus, Anolis, and Scincella showed the typical righting response and enormous amounts of body motion and tail rotation, which we interpreted as both righting responses and futile actions to grasp the substrate. Both arboreal and non-arboreal geckos in the genera Uroplatus, Palmatogecko, Stenodactylus, Tarentola, and Eublepharis instead showed a skydiving posture previously reported for highly arboreal anurans. Some snakes, in the genera Thamnophis and Elaphe, which typically thrashed and rolled in mug, managed to knot their own bodies with their tails and immediately became quiescent. This suggests that these reptiles gave stable physical contact, which would indicate that they were not falling, primacy over vestibular input that indicated that they were in freefall. The fact that they became quiet upon self-embrace further suggests a failure to distinguish self from non-self. The patterns of behavior seen in amphibians and reptiles in mug can be explained in light of their normal ecology and taxonomic relations.     

Evolutionary and cellular mechanisms regulating intestinal performance of amphibians and reptiles

Vertebrate intestinal tracts possess an array of structuraland functional adaptations to the wide diversity of food andfeeding habits. In addition to well-described differences inform and function between herbivores and carnivores, the intestineexhibits adaptive plasticity to variation in digestive demand.The capacity to which intestinal performance responds to changesin digestive demands is a product of evolutionary and cellularmechanisms. In this report, I have taken an integrative approachto exploring the mechanisms responsible for the regulation ofintestinal performance with feeding and fasting among amphibiansand reptiles. Intestinal performance is presented as the totalsmall intestinal capacity to absorb nutrients, quantified asa product of small intestinal mass and mass-specific rates ofnutrient uptake. For sit-and-wait foraging snakes and estivatinganurans, both of which naturally experience long episodes offasting, the dramatic downregulation of intestinal morphologyand function with fasting reduces energy expenditure duringextended fasts. In contrast, frequently-feeding species modestlyregulate intestinal performance with fasting and feeding, tradinghigher basal rates of metabolism during fasting for the frequentexpense of upregulating the gut with feeding. Surveying themagnitude by which intestinal uptake capacity is regulated among26 families of amphibians and reptiles has revealed potentiallyfive lineages that have independently evolved the capacity towidely regulate intestinal performance. The extent to whichintestinal performance is downregulated with fasting among amphibiansand reptiles, ranging from 0 to 90%, is largely a function ofthe degree by which mass-specific rates of nutrient transportare depressed, given that loss of intestinal mass with fastingis a common characteristic of vertebrates. In exploring theunderlying mechanisms regulating intestinal nutrient uptake,use of the Burmese python has revealed a temporal match betweenmicrovillus surface area and intestinal nutrient transport.With feeding, pythons experience a five-fold lengthening ofintestinal microvilli, with subsequent reduction after completingdigestion. Identifying for the python the cellular processesresponsible for the dramatic remodeling of the microvilli wouldassist in elucidating the mechanisms by which intestinal performanceis regulated, as well as identify whether similar steps areemployed by other species to regulate their intestines. In finishing,I propose three studies of digestive response: (1) investigatethe responses of the ectotherm intestine to hibernation; (2)evaluate whether functional capacities of tissues are matchedto digestive demands; and, (3) apply microarray technology toexplore the functional genomics of intestinal adaptation.     

河北沧州地区两栖爬行动物多样性研究

2001年5月～2007年10月对沧州地区的两栖爬行动物进行了调查,共记录两栖爬行动物21种,分隶于3目10科14属.其中两栖纲1目3科3属6种;爬行纲2目7科11属15种,其中外来种3种,本地种2目5科8属12种.区系成分以广布种和古北种为主.