From Holarctic to Indomalaya, the evolution of the East Asian monsoon drove the phylogeography, latitudinal expansion and induced convergent adaptation of subarctic Eurasian true frogs to overwintering
Description
Past and present climates are known to be the main driver of phylogeographical diversity, specifically for species distributed under a broad climate variability, such circumstance induces ecological trait divergences, and results in their thermal adaptability. Consequential to the ancient dispersal out of Asia and into the Nearctic in Rana, we argue that trait related to latitudinal trend in range size drives the present phylogeny and phylogeography pattern of Rana, inducing the adaptability of subarctic clade to overwintering. We integrated phylogenetic comparative methods and phylogeography to test for latitudinal trend in range size of 74 Holarctic and Indomalayan ranids across latitude zones. We also tested the association between climate variability and repeated radiations of Asian Rana in the Palearctic (470 sampled Rana individuals). Finally, we clarified the significant impact of two bioclimatic variables, average of minimum temperature in the coldest month (BIO 6) and annual precipitation (BIO 12) on the evolution of latitudinal trends in range size of Palearctic Rana.. Our findings highlight latitudinal trends in range size trait is convergent in Holarctic-Indomalayan ranids, independently evolved in ranid clades of different geographic regions but with the same temperate to subarctic climate: Lithobates catesbeianus, Pelophylax ridibundus, R. amurensis, and R. temporaria. Paleogeographic models highlight a massive impact of the Asian monsoonal system on the repeated radiations of Rana in Central Asian. The vicariances and dispersals may have induced the range expansion of R. amurensis into the Siberian-subarctic c. 7.7 Mya, coinciding with the warmer-than-today condition of the Arctic in the Late Miocene. This study demonstrates a pattern of climate-inducing gradual adaptation of the subarctic R. amurensis clade to high altitudes climate in the subarctic.