Rapid genetic divergence and mitonuclear discordance in the Taliang knobby newt (<i>Liangshantriton taliangensis,</i> Salamandridae, Caudata) and their driving forces

Abstract

The Hengduan Mountains Region (HMR) is the largest “evolutionary frontier” of the northern temperate zone, and the origin and maintenance of species in this area is a research hotspot. Exploring species-specific responses to historical and contemporary environmental changes will improve our understanding of the role of this region in maintaining biodiversity. In this study, mitochondrial and microsatellite diversities were used to assess the contributions of paleogeological events, Pleistocene climatic oscillations, and contemporary landscape characteristics to the rapid intraspecific diversification of Liangshantriton taliangensis , a vulnerable amphibian species endemic to several sky-island mountains in the southeastern HMR. Divergence date estimations suggested that the East Asian monsoon, local uplifting events (Xigeda Formation strata), and Early-Middle Pleistocene transition (EMPT) promoted rapid divergence of L. taliangensis during the Pleistocene, yielding eight mitochondrial lineages and six nuclear genetic lineages. Moreover, population genetic structures were mainly fixed through isolation by resistance. Multiple in situ refugia were identified by ecological niche models and high genetic diversity, which played crucial roles in the persistence and divergence of L. taliangensis during glacial-interglacial cycles. Dramatic climatic fluctuations further promoted recurrent isolation and admixing of populations in scattered glacial refugia. The apparent mitonuclear discordance was likely the result of introgression by secondary contact and/or female-biased dispersal. Postglacial expansion generated two major secondary contact zones (Ganluo (GL) and Chuhongjue (CHJ)). Identification of conservation management units and dispersal corridors offers important recommendations for the conservation of this species.

A wide hybrid zone mediated by precipitation contributed to confused geographical structure of <i>Scutiger</i> <i>boulengeri</i>

“…Lin et al ( 2021 ) proposed that niche divergence caused by northward niche expansion accompanied key morphological innovations of adaptation to novel climates. Our research showed that IBE contributed to the divergent population structure ( Figure 7B , C), as reported for the Taliang knobby newt ( Liangshantriton taliangensis , Shu et al, 2022 ), suggesting that gene flow rates are higher among similar environments and environmental variables can influence colonization success of individuals and groups via environmental filtering, with higher effective gene movement among similar environments ( García-Girón et al, 2019 ; Sexton et al, 2014 ).…”

Landscape Heterogeneity Explains the Genetic Differentiation of a Forest Bird across the Sino-Himalayan Mountains

“…Resistance distance calculations in IBR often utilize data related to species traits or habitats ( Thomas et al 2015 ; Weber et al 2017 ). One common method is to calculate resistance distance based on niche model predictions, since gene flow between populations can be limited by suitable habitats ( Myers et al 2019 ; Zhang et al 2020 ; Shu et al 2022 ; Moreno-Contreras et al 2023 ). In IBE and IBR analyses, based on L. lutea 's elevational distribution range and preference for evergreen broadleaved forest and woodland, we considered 2 other variables in addition to the bioclimatic factors, namely altitude and land cover.…”

Genomic insights into the Montseny brook newt (Calotriton arnoldi), a Critically Endangered glacial relict

“… 34 Post-glacial population expansions after LGM and LGP have been inferred for many vertebrate groups, 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 including Eurasian salamandrids from similar latitudes. 43 , 44 , 45 However, well documented post-glacial bottlenecks are scarcer in the genomic literature and typically limited to either relict or extinct megafauna. 37 , 46 , 47 , 48 , 49 Although paleodemographic modeling has statistically shown tight links between demography and climate oscillations for humans at the end of LGP from archaeological radiocarbon dates, 39 , 50 to our knowledge this is the first time the dependence of a genomically inferred past demography on climate variables is proven, moreover, on a non-model species.…”