Database of Amphibia distribution in West Siberia (Russia)

Background

West Siberia is a large region in North Eurasia, which harbours multiple climatic zones, landscape types and biomes. Its amphibian fauna is characterised by a combination of European and Asian species. For many species, this region is the place where the limits of their global ranges are located (Ranatemporaria, R.amurensis, Bufotessitibundus). West Siberia also has at least two non-native amphibian species (Pelophylaxridibundus, Bufotesviridis). The exact ranges and patterns of distribution of the West Siberian amphibian species are poorly studied. The mapping of species ranges is important for the development of conservation measures and monitoring of invasive species is required to investigate their impacts on the natural ecosystems.

New information

This work presents the most complete biogeographic and occurrence records database of the amphibians of West Siberia. To assemble the database, we digitised data from 190 published works, obtained data from major museum collections and from the data bank on the abundance and distribution of animals «Zoomonitor» by the Zoomonitoring laboratory of the Institute of Systematics and Ecology of Animals, Siberian Branch of Russian Academy of Sciences. The database also includes original and partly unpublished data collected by the authors from 1975 to 2021, as well as quality-assessed citizen science data from the iNaturalist portal. In total, the database contains 2530 records for 11 species of amphibians, including the locality data, the observation date (when known) and the source of the observation (at least one of the following: literature reference, museum sample ID, observer's name, iNaturalist link).

Diversity, distribution and molecular species delimitation in frogs and toads from the Eastern Palaearctic

Biodiversity analyses can greatly benefit from coherent species delimitation schemes and up-to-date distribution data. In this article, we have made the daring attempt to delimit and map described and undescribed lineages of anuran amphibians in the Eastern Palaearctic (EP) region in its broad sense. Through a literature review, we have evaluated the species status considering reproductive isolation and genetic divergence, combined with an extensive occurrence dataset (nearly 85k localities). Altogether 274 native species from 46 genera and ten families were retrieved, plus eight additional species introduced from other realms. Independent hotspots of species richness were concentrated in southern Tibet (Medog County), the circum-Sichuan Basin region, Taiwan, the Korean Peninsula and the main Japanese islands. Phylogeographic breaks responsible for recent in situ speciation events were shared around the Sichuan Mountains, across Honshu and between the Ryukyu Island groups, but not across shallow water bodies like the Yellow Sea and the Taiwan Strait. Anuran compositions suggested to restrict the zoogeographical limits of the EP to East Asia. In a rapidly evolving field, our study provides a checkpoint to appreciate patterns of species diversity in the EP under a single, spatially explicit, species delimitation framework that integrates phylogeographic data in taxonomic research.

Amphibian and Reptilian Chorotypes in the Arid Land of Central Asia and Their Determinants

The analysis of the biogeographic distribution of species is the basis for establishing a strategy for land management and responding to climatic change, but research on the distribution of amphibians and reptiles in the arid land in the middle of Asia is extremely limited. After classifying the chorotypes of amphibians and reptiles in the arid land of Central Asia using a clustering analysis, we delineated their distribution characteristics and discovered the ecological determinants for the chorotypes in terms of feature selection and the Akaike information criterion (AIC). We identified 6 chorotypes at the higher level and 16 sub-chorotypes at the lower level. Compared to small-scale or subjective research, which produces unstable results, research characterized by both large scale and clustering methods yields more consistent and stable results. Our results show that the Mean Altitude (MA), Mean Annual Temperature (MAT), and Mean Temperature in the Wettest Quarter (MTWE) are the critical variables determining the higher-level chorotypes. Furthermore, geographical factors appear to have a stronger influence on chorotypes than climatic factors. Several climatic variables and MA were identified as the best fit in the AIC model at the lower level, while the sub-chorotypes are determined more by multiple climatic factors with complex relationships. The research on amphibian and reptilian distribution patterns will shed light on the overall distribution of other species in the same understudied area. Widespread species in the study area are not clearly distinguished due to the cluster analysis computing process. This problem however, appears in studies of the distribution of other organisms thus warrants further research. Our methodology based on the selection of multiple models is effective to explore how the environment determines the distributions of different animal groups.

Neogene amphibians and reptiles (Caudata, Anura, Gekkota, Lacertilia, and Testudines) from the south of Western Siberia, Russia, and Northeastern Kazakhstan

Background

The present-day amphibian and reptile fauna of Western Siberia are the least diverse of the Palaearctic Realm, as a consequence of the unfavourable climatic conditions that predominate in this region. The origin and emergence of these herpetofaunal groups are poorly understood. Aside from the better-explored European Neogene localities yielding amphibian and reptile fossil remains, the Neogene herpetofauna of Western Asia is understudied. The few available data need critical reviews and new interpretations, taking into account the more recent records of the European herpetofauna. The comparison of this previous data with that of European fossil records would provide data on palaeobiogeographic affiliations of the region as well as on the origin and emergence of the present-day fauna of Western Siberia. An overview of the earliest occurrences of certain amphibian lineages is still needed. In addition, studies that address such knowledge gaps can be useful for molecular biologists in their calibration of molecular clocks.

Methods and Results

In this study, we considered critically reviewed available data from amphibian and reptile fauna from over 40 Western Siberian, Russian and Northeastern Kazakhstan localities, ranging from the Middle Miocene to Early Pleistocene. Herein, we provided new interpretations that arose from our assessment of the previously published and new data. More than 50 amphibians and reptile taxa were identified belonging to families Hynobiidae, Cryptobranchidae, Salamandridae, Palaeobatrachidae, Bombinatoridae, Pelobatidae, Hylidae, Bufonidae, Ranidae, Gekkonidae, Lacertidae, and Emydidae. Palaeobiogeographic analyses were performed for these groups and palaeoprecipitation values were estimated for 12 localities, using the bioclimatic analysis of herpetofaunal assemblages.

Conclusion

The Neogene assemblage of Western Siberia was found to be dominated by groups of European affinities, such as Palaeobatrachidae, Bombina, Hyla, Bufo bufo, and a small part of this assemblage included Eastern Palaearctic taxa (e.g. Salamandrella, Tylototriton, Bufotes viridis). For several taxa (e.g. Mioproteus, Hyla, Bombina, Rana temporaria), the Western Siberian occurrences represented their most eastern Eurasian records. The most diverse collection of fossil remains was found in the Middle Miocene. Less diversity has been registered towards the Early Pleistocene, potentially due to the progressive cooling of the climate in the Northern Hemisphere. The results of our study showed higher-amplitude changes of precipitation development in Western Siberia from the Early Miocene to the Pliocene, than previously assumed.

The adder (Vipera berus) in Southern Altay Mountains: population characteristics, distribution, morphology and phylogenetic position

As the most widely distributed snake in Eurasia, the adder (Vipera berus) has been extensively investigated in Europe but poorly understood in Asia. The Southern Altay Mountains represent the adder's southern distribution limit in Central Asia, whereas its population status has never been assessed. We conducted, for the first time, field surveys for the adder at two areas of Southern Altay Mountains using a combination of line transects and random searches. We also described the morphological characteristics of the collected specimens and conducted analyses of external morphology and molecular phylogeny. The results showed that the adder distributed in both survey sites and we recorded a total of 34 sightings. In Kanas river valley, the estimated encounter rate over a total of 137 km transects was 0.15 ± 0.05 sightings/km. The occurrence of melanism was only 17%. The small size was typical for the adders in Southern Altay Mountains in contrast to other geographic populations of the nominate subspecies. A phylogenetic tree obtained by Bayesian Inference based on DNA sequences of the mitochondrial cytochrome b (1,023 bp) grouped them within the Northern clade of the species but failed to separate them from the subspecies V. b. sachalinensis. Our discovery extends the distribution range of V. berus and provides a basis for further researches. We discuss the hypothesis that the adder expands its distribution border to the southwest along the mountains' elevation gradient, but the population abundance declines gradually due to a drying climate.