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

Abstract

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.

Piecing the barcoding puzzle of Palearctic water frogs (Pelophylax) sheds light on amphibian biogeography and global invasions

“…ridibundus ”. At the same time, taxonomic accounts disagree on the validity and species/subspecies rank of many described taxa, depending on the applied concepts and criteria (e.g., P. ridibundus / kurtmuelleri ; P. bedriagae/cypriensis/caralitanus/cerigensis ; P. plancyi/hubeiensis/chosenicus ; see Dufresnes & Litvinchuk, 2022; Frost, 2023; Speybroeck et al., 2020). Solving the taxonomy of water frogs thus appears urgent if distinct lineages are to be independently treated in national and international legislation, which will be necessary to ban invasive lineages from being imported, to eradicate them in invaded areas (when feasible), and to protect them in their native range, where unsustainable harvest is causing significant population declines (Çiçek et al., 2020).…”

“…In the EP, extant clades emerged during the Late Miocene (~9 Mya), potentially linked to the re‐intensification of the East Asian monsoon (dated to ~9.5 Mya by Sun, Ma, et al., 2015; h in Figure 10), which itself was associated with the retreat of Paratethys alongside phases of QTP growth (Zhang et al., 2007, 2021). Although it is more frequently invoked for plant biogeography (e.g., Ma et al., 2019), strengthening of the monsoon regime may be a key driver of amphibian divergence in the EP, especially in Chinese species groups with inland and coastal lineages that likely diversified during the Late Miocene (see numerous examples in Dufresnes & Litvinchuk, 2022). Hence, the Parathetys domain appears a major biogeographic determinant of Palearctic amphibians at the global scale, both directly as a fluctuating physical barrier, and indirectly due to its influence on the Asian paleo‐climate.…”

“…Water frogs are also particularly suitable for timetree plausibility tests. Their widespread distribution warrants many paleographic candidate events of vicariance for the BPT, both in the western (Ehl et al., 2019) and the eastern (Dufresnes & Litvinchuk, 2022) regions of the Palearctic. In addition, the outcome of hybridization between taxa has been relatively well‐documented, both regarding hybridogenetic mechanisms (reviewed by Dufresnes & Mazepa, 2020) and the contact zones between several phylogeographic lineages (e.g., Dufresnes & Dubey, 2020; Hotz et al., 2013; Nagai et al., 2018; Papežík et al., 2021; Sagonas et al., 2020; Santucci et al., 1996), thus allowing to experiment the use of the LCPT for the first time.…”

Inferring genetic structure when there is little: population genetics versus genomics of the threatened bat Miniopterus schreibersii across Europe

“…They accordingly remain popular markers to estimate gene flow and diversity among recently diverged populations ever since the late 1990s 18 , 19 . Also highly polymorphic, mitochondrial DNA (mtDNA) is more straightforward and cheaper to analyze, notably across evolutionary distant populations, and has accordingly been preferred by researchers interested in range-wide phylogeographic structure 20 . However, mtDNA faces inherent limitations with respect to its clonal nature and maternal mode of inheritance, which makes it more sensitive to selection 21 and can bias the reconstruction of the demographic history of populations, especially when dispersal is sex-biased 22 – 24 .…”

Genetic diversity and demography of Bufo japonicus and B. torrenticola (Amphibia: Anura: Bufonidae) influenced by the Quaternary climate

“…These two subspecies are distributed parapatrically, and the boundary is in the Kinki region ( Matsui & Maeda, 2018 ). Since the most recent paper proposes raising the two subspecies to the species level ( Dufresnes & Litvinchuk, 2021 ), we herein adopted two subspecies and will discuss the species concept based on nuclear markers in a future study. In contrast to B. japonicus , the range of B. torrenticola is limited to the mountainous areas of central Honshu, with lotic breeding habits unique to Bufo .…”