Lineage diversification and historical demography of a montane bird Garrulax elliotii - implications for the Pleistocene evolutionary history of the eastern Himalayas

Abstract

BackgroundPleistocene climate fluctuations have shaped the patterns of genetic diversity observed in many extant species. In montane habitats, species' ranges may have expanded and contracted along an altitudinal gradient in response to environmental fluctuations leading to alternating periods of genetic isolation and connectivity. Because species' responses to climate change are influenced by interactions between species-specific characteristics and local topography, diversification pattern differs between species and locations. The eastern Himalayas is one of the world's most prominent mountain ranges. Its complex topography and environmental heterogeneity present an ideal system in which to study how climatic changes during Pleistocene have influenced species distributions, genetic diversification, and demography. The Elliot's laughing thrush (Garrulax elliotii) is largely restricted to high-elevation shrublands in eastern Himalayas. We used mitochondrial DNA and microsatellites to investigate how genetic diversity in this species was affected by Pleistocene glaciations.ResultsMitochondrial data detected two partially sympatric north-eastern and southern lineages. Microsatellite data, however, identified three distinct lineages congruent with the geographically separated southern, northern and eastern eco-subregions of the eastern Himalayas. Geographic breaks occur in steep mountains and deep valleys of the Kangding-Muli-Baoxin Divide. Divergence time estimates and coalescent simulations indicate that lineage diversification occurred on two different geographic and temporal scales; recent divergence, associated with geographic isolation into individual subregions, and historical divergence, associated with displacement into multiple refugia. Despite long-term isolation, genetic admixture among these subregional populations was observed, indicating historic periods of connectivity. The demographic history of Garrulax elliotii shows continuous population growth since late Pleistocene (about 0.125 mya).ConclusionWhile altitude-associated isolation is typical of many species in other montane regions, our results suggest that eco-subregions in the eastern Himalayas exhibiting island-like characteristics appear to have determined the diversification of Garrulax elliotii. During the Pleistocene, these populations became isolated on subregions during interglacial periods but were connected when these expanded to low altitude during cooler periods. The resultant genetic admixture of lineages might obscure pattern of genetic variation. Our results provide new insights into sky island diversification in a previously unstudied region, and further demonstrate that Pleistocene climatic changes can have profound effects on lineage diversification and demography in montane species.

Pleistocene climate changes shaped the divergence and demography of Asian populations of the great tit Parus major: evidence from phylogeographic analysis and ecological niche models

“…MIS is a timescale that is now widely used to express warm and cool periods in the Quaternary (Ogg et al 2008). A similar pre‐LGM expansion has also been detected in other east Asian bird species (Li et al 2009, Dai et al 2011, Qu et al 2011). This difference of demographic patterns between European and east Asian populations seems to be inevitable.…”

“…Previous studies of east Asian avifauna have highlighted genetic differentiation, unusual historical demography and the existence of multiple refugia during glacial periods (Johansson et al 2007, Zou et al 2007, Li et al 2009, Qu and Lei 2009, Song et al 2009, Liu et al 2010, Qu et al 2011). Although the consensus is that the last glacial maximum (LGM) had a limited effect on species’ distribution and demography (Li et al 2009, Dai et al 2011, Qu et al 2011), these studies focused primarily on endemic species in south China or southwest China. Additional research on a species with a Pan‐Eurasian distribution is therefore required to confirm the generality of existing hypotheses on how Pleistocene climate change affected species diversi fication and demography.…”

Genetic Structure and Evolutionary History of Three Alpine Sclerophyllous Oaks in East Himalaya-Hengduan Mountains and Adjacent Regions

“…When combined with the general lack of IBD, The island-like population genetic structure of three oak species in accordance with their highly fragmented habitats located in the EH-HM region, and largely driven by historical effects of genetic drift rather than currently limited gene flow alone (Hutchison and Templeton, 1999). In fact, similar genetic structure have also been detected in other species in this region, such as Garrulax elliotii from the eastern Himalayas (Qu et al, 2011) and four herbs from HHM region (Luo et al, 2015). …”

Effect of Pleistocene Climatic Oscillations on the Phylogeography and Demography of Red Knobby Newt (Tylototriton shanjing) from Southwestern China

“…Records of ice core and pollen have indicated a series of warm and humid stages during Marine Isotope Stages 5 [68]. An equivalent expansion time was also estimated in a montane bird Garrulax elliotii by Qu et al [69]. Likely, the sympatric distribution of lineages D and A at Yuanjiang County is the consequence of the expansion of sub-lineage D2.…”