Ancient hybridization and underestimated species diversity in Asian striped squirrels (genus Tamiops ): inference from paternal, maternal and biparental markers

Abstract

Current classification of the genus Tamiops is mainly based on pelage color pattern that is prone to seasonal variation or convergent adaptation to environmental selection. The arrangement of four species, Tamiops mcclellandii, Tamiops rodolphii, Tamiops swinhoei and Tamiops maritimus, is regarded as tentative due to difficulty in delineating species, especially the latter two species. We constructed multi-locus phylogenies of all four Tamiops species on the basis of paternal (Y-chromosomal SRY and SMCY7), maternal (mitochondrial cytochrome b gene) and biparental (autosomal IRBP, RAG1 and PRKCI) sequences. Maximum likelihood and Bayesian tree-constructing methods resulted in phylogenies with similar topologies. All genetic markers supported diversification of three main lineages: (1) T. mcclellandii;(2) T. rodolphii; (3) T. swinhoei-maritimus complex. On the basis of 24 T. maritimus from five localities and 10 T. swinhoei from four localities, T. swinhoei and T. maritimus were not reciprocally monophyletic. The six populations of the T. swinhoei-maritimus complex were monophyletic in all loci, except for autosomal loci in one T. maritimus population from Tam Dao, Vietnam. Autosomal phylogenies were more similar to Y-chromosomal than to mitochondrial phylogenies. Incongruence between nuclear and mitochondrial phylogenies indicates that either T. maritimus from Taiwan or T. maritimus from Phu Yen, Vietnam probably descended from ancient hybridization. Diversification of the three main Tamiops lineages was estimated to occur 8.8-6.7 million years ago (mya) and may have been affected by rapid uplift of the Himalayan Mountains in the western part of their range. Multiple divergences from 5.8 to 1.7 mya likely led to the formation of modern Tamiops species. All six populations of T. swinhoei-maritimus complex could be regarded as distinct species. Divergence among T. rodolphii populations in mitochondrial DNA was also at the interspecies level. Our analyses highlight the underestimation of species diversity in the genus Tamiops.

Molecular phylogeographic analyses and species delimitations reveal that Leopoldamys edwardsi (Rodentia: Muridae) is a species complex

“…Subsequently during the interglacial period, rising sea levels isolated Hainan Island and triggered the genetic divergence between L HN and L S . Different from the phylogenetic trees based on mitochondrial genes, the trees of nuclear genes showed that our specimens from the 2 sampling sites, Longzhou (Site 6) and Yongshun (Sites 10), formed a monophyletic group (L W ), inferring the ancient hybridization between lineages L N and L S in these regions (Chang et al 2011). These 2 sampling sites are approximately 500 m in elevation, located in the transient zone between the second and third topography steps of China (Fig.…”

Evolutionary history and species delimitations: a case study of the hazel dormouse, Muscardinus avellanarius

“…Two M. avellanarius species would be recognized under the GSC (Baker and Bradley 2006). The cytb divergence between Lineage 1 and Lineage 2 is high (10.3 %) and comparable to that found between Asian striped squirrels (genus Tamiops; T. maritimus and T. swinhoei) (Chang et al 2011) or between dormice species (genus Eliomys; E. quercinus and E. melanurus) (Montgelard et al 2003). However, recent studies have also revealed that ''intraspecific'' divergences in species from monotypical genera can be also very deep (e.g.…”

Genetic characterization ofCallosciurus(Rodentia: Sciuridae) Asiatic squirrels introduced in Argentina

“…Regional variation in C. finlaysonii is so extreme that it is doubtful that all these forms constitute discrete species (Corbet & Hill 1992), while hybrids may occur in certain regions where both species occur (Moore & Tate 1965;Timmins & Duckworth 2008). Genetic introgression between subspecies, and even between species, has been reported in other squirrels given the hybridization that frequently occurs in pet markets and stores (Wettstein et al 1995;Good et al 2008;Hird & Sullivan 2009;Chang et al 2011). Oshida et al (2007) and Kuramoto et al (2012) concluded that the squirrels introduced into Japan that had been identified as C. erythraeus but were genetically closer to C. finlaysonii could be regarded either as C. finlaysonii or as hybrids between both species.…”