Date Published: April 3, 2017
Publisher: Public Library of Science
Author(s): Yu Zhou, Sirui Wang, Hedan Zhu, Pipeng Li, Baotian Yang, Jianzhang Ma, Bi-Song Yue.
Few studies have explored the role of Cenozoic tectonic evolution in shaping the patterns and processes of extant animal distributions in and around East Asia. In this study, we selected South Chinese brown frogs as a model to examine the phylogenetic and biogeographical consequences of Miocene tectonic events within South China and its margins. We used mitochondrial and nuclear molecular data to reconstruct phylogenetic interrelationships among Chinese brown frogs using Bayesian and maximum likelihood analyses. The phylogeny results show that there are four main clades of Chinese brown frogs. Excepting the three commonly known Chinese brown frog species groups, R. maoershanensis forms an independent clade nearest to the R. japonica group. Phylogeny and P-distance analyses confirmed R. maoershanensis as a valid species. Among South Chinese brown frogs, there are four subclades associated with four geographical areas: (I) R. maoershanensis; (II) R. japonica; (III) R. chaochiaoensis; and (IV) other species of the R. longicrus species group. Divergence times, estimated using mitochondrial sequences, place the vicariance events among the four subclades in the middle to late Miocene epoch. Our results suggest that (1) South Chinese brown frogs originated due to a vicariance event separating them from the R. chensinensis species group at the time of the Geological movement (~18 million years ago, Ma) in southern Tibet and the Himalayan region; (2) the separation and speciation of R. maoershanensis from the R. japonica group occurred due to the dry climate at approximately 16 Ma; (3) South Chinese brown frogs migrated from South China to Japan at the time (~10.8 Ma) that the global sea-level fell and the East China Sea Shelf Basin was swamp facies, when a land gallery may have formed across the sea to connect the two areas; and (4) R. chaochiaoensis separated from other species of the R. longicrus species group during the uplift of the Tibetan Plateau at approximately 9.5 Ma.
The taxonomy of Rana (brown frogs), a genus of the family Ranidae, has been intensely debated in the last 20 years. Rana is widely distributed from the Western Palearctic to Northeast Asia. South China is one of the most richly diverse regions for brown frogs, with approximately 12 species [1, 2]. Most South Chinese brown frogs are classified in the Rana longicrus species group, which is one of the major species groups of Chinese brown frogs; the other two species groups are the R. chensinensis group and the R. amurensis species group [3, 4]. Additionally, the frogs of the R. longicrus species group were first known as the R. japonica group [5, 6] prior to their recognition as a new species and their classification into the R. longicrus species group based on morphological and nucleotide differences [4, 5].
Although previous studies have disagreed on the taxonomic status of R. maoershanensis , our phylogeny confirms the validity of this species. We performed phylogenetic analyses on independent genetic datasets (mtDNA and mtDNA+nuDNA), and all of our results recovered a monophyletic R. maoershanensis (Fig 2) that is distinct from the three other commonly known Chinese Rana species groups.