The distribution and taxonomy of Lissotriton newts in Turkey (Amphibia, Salamandridae)

An extensive database on the traits and occurrences of amphibian species in Turkey

Amphibians are the most endangered taxa among vertebrates, and they face many threats during their complex life cycles. The species' life history traits and occurrence database help understand species responses against ecological factors. Consequently, the species-level-trait database has gained more prominence in recent years as a useful tool for understanding the dimensions of communities, assembly processes of communities, and conserving biodiversity at the ecosystem level against environmental changes. However, in Turkey, there are deficiencies in the knowledge of the ecological traits of amphibians compared to other vertebrate taxa, as most studies have focused on their distribution or taxonomic status. Consequently, there is a need to create such a database for future research on all known extant amphibians in Turkey. We compiled a species-level data set of species traits and occurrences for all amphibians in Turkey using 436 literature sources. We completed 36 trait categories with 5611 occurrence data for 37 amphibian species in Turkey. This study provides an open, useful, and comprehensive database for macroecological and conservation studies on amphibians in Turkey.

Easternmost distribution of Bufo bufo (Linnaeus, 1758) in Türkiye: implications for the putative contact zone between B. bufo and B. verrucosissimus

The geographic range of a species is crucial for obtaining information on the exact distribution of the species. The geographic data are important for delimiting distinct species or exploring the degree of differentiation among different populations of a species. The local details of species boundaries facilitate the study of the importance of phylogeographic background, secondary contacts, and hybrid zones, along with the relations between the species and its extrinsic environmental factors. In the present study, the range boundaries of Bufo bufo and Bufo verrucosissimus in the north-eastern region of Türkiye were delineated using an integrative taxonomic approach that utilized a combination of molecular and morphological data. According to the mtDNA results of the present study, B. bufo inhabits a single distribution from İyidere town to Çayeli town in Rize, while B. verrucosissimus is distributed from Şavşat town of Artvin to Ardeşen town in Rize. In addition, the two species coexist in Pazar, Hemşin, and Çamlıhemşin towns in Rize. The demographic analyses indicated a distinct population expansion for the B. verrucosissimus species after the Last Glacial Maximum, while the same did not occur for B. bufo. The univariate and multivariate statistical analyses conducted for the morphological data of the two species corroborated the presence of a putative contact zone between B. bufo and B. verrucosissimus. In summary, the present study resolved the non-distinct geographic boundaries between B. bufo and B. verrucosissimus species and also revealed the easternmost distribution of B. bufo in Türkiye. In addition, important evidence on the putative contact zone between the two species was indicated using an integrative taxonomic approach.

Ventral and lateral spot patterns differentiation between three smooth newt species (Amphibia: Salamandridae: Lissotriton)

The location, shape and area of dark spots on the belly, throat and sides of the body of three closely related species of smooth newts (Lissotriton kosswigi, L. schmidtleri and L. vulgaris) were analysed. Differences were found between species and sexes in the location and shape of dark spots on the belly, throat and lateral surfaces of the body. Discriminant analysis of these spot characteristics allows to identificate of males of all three species with a high degree of confidence (85–91%). In females, only L. vulgaris was correctly distinguished from the other two species (accuracy 81–94%). Anatolian and Thracian populations of L. schmidtleri have very similar patterns of dark spots, which confirm their conspecificity. The differences in the location and size of dark spots make possible successful identification of the species during field research and study of museum specimens. The developed method could be useful for comparative studies of other animal species which have spotted camouflage or aposematic colouration.

The distributions of the six species constituting the smooth newt species complex (Lissotriton vulgaris sensu lato and L. montandoni) – an addition to the New Atlas of Amphibians and Reptiles of Europe

The ‘smooth newt’, the taxon traditionally referred to as Lissotriton vulgaris, consists of multiple morphologically distinct taxa. Given the uncertainty concerning the validity and rank of these taxa, L. vulgaris sensu lato has often been treated as a single, polytypic species. A recent study, driven by genetic data, proposed to recognize five species, L. graecus, L. kosswigi, L. lantzi, L. schmidtleri and a more restricted L. vulgaris. The Carpathian newt L. montandoni was confirmed to be a closely related sister species. We propose to refer to this collective of six Lissotriton species as the smooth newt or Lissotriton vulgaris species complex. Guided by comprehensive genomic data from throughout the range of the smooth newt species complex we 1) delineate the distribution ranges, 2) provide a distribution database, and 3) produce distribution maps according to the format of the New Atlas of Amphibians and Reptiles of Europe, for the six constituent species. This allows us to 4) highlight regions where more research is needed to determine the position of contact zones.

Isolation and gene flow in a speciation continuum in newts

Because reproductive isolation often evolves gradually, differentiating lineages may retain the potential for genetic exchange for prolonged periods, providing an opportunity to quantify and to understand the fundamental role of gene flow during speciation. Here we delimit evolutionary lineages, reconstruct the phylogeny and infer gene flow in newts of the Lissotriton vulgaris species complex based on 74 nuclear markers sampled from 127 localities. We demonstrate that distinct lineages along the speciation continuum in newts exchange nontrivial amounts of genes, affecting their evolutionary trajectories. By integrating a wide array of methods, we delimit nine evolutionary lineages and show that two principal factors have driven their genetic differentiation: time since the last common ancestor determining levels of shared ancestral polymorphism, and shifts in geographic distributions determining the extent of secondary contact. Post-divergence gene flow, indicative of evolutionary non-independence, has been most extensive in Central Europe, while four southern European lineages have acquired the population-genetic hallmarks of independent species (L. graecus, L. kosswigi, L. lantzi, L. schmidtleri). We obtained strong statistical support for widespread mtDNA introgression following secondary contact, previously suggested by discordance between mtDNA phylogeny and morphology. Our study reveals long-term evolutionary persistence of evolutionary lineages that may periodically exchange genes with one another: although some of these lineages may become extinct or fuse, others will acquire complete reproductive isolation and will carry signatures of this complex history in their genomes.