Quaternary climate change drives allo-peripatric speciation and refugial divergence in the Dysosma versipellis-pleiantha complex from different forest types in China

Abstract

Subtropical China harbours the world’s most diverse temperate flora, but little is known about the roles of geographical and eco-climatic factors underlying the region’s exceptionally high levels of species diversity and endemism. Here we address this key question by investigating the spatio-temporal and ecological processes of divergence within the Dysosma versipellis-pleiantha species complex, endemic to subtropical China. Our cpDNA phylogeny showed that this monophyletic group of understory herbs is derived from a Late Pliocene ancestor of the Qinghai-Tibetan Plateau (QTP)/Southwest China. Genetic and ENM data in conjunction with niche differentiation analyses support that the early divergence of D. versipellis and D. pleiantha proceeded through allo-peripatric speciation, possibly triggered by Early Pleistocene climate change, while subsequent climate-induced cycles of range contractions/expansions enhanced the eco-geographical isolation of both taxa. Furthermore, modelling of population-genetic data indicated that major lineage divergences within D. versipellis likely resulted from long-term allopatric population isolation in multiple localized refugia over the last glacial/interglacial periods, and which in turn fostered endemic species formation (D. difformis, D. majoensis) from within D. versipellis in Southwest China. These findings point to an overriding role of Quaternary climate change in triggering essentially allopatric (incipient) speciation in this group of forest-restricted plant species in subtropical China.

Interspecific Divergence of Two Sinalliaria (Brassicaceae) Species in Eastern China

“…Second, S. limprichtiana prefers dry habitats while S. grandifolia occurs in the wet habitats along the stream. These contrasted habitats may have produced strong selection pressure on the differentiations of two species (Wang et al, 2017 ). Finally, the effective population sizes of both species are small.…”

“…First, numerous ancient genera and species may have persisted due to geographical and ecological heterogeneity that could buffered the organisms from small-scale extinctions caused by the climate oscillations in eastern Asia, in conjunction with the lack of Pleistocene glaciation and subsequent large-scale extinctions. Second, many young species (for example, four Dysosma species, D. pleiantha, D. versipellis, D. difformis , and D. majoensis ) have originated through fast divergence probably driven by Pleistocene climate oscillations in conjunction with physiographic heterogeneity (Ikeda et al, 2012 ; Han et al, 2016 ; Wang et al, 2017 ). Both hypotheses have been partly tested based on biogeographic analyses of a few genera and phylogeographic examinations of some widely distributed species (see summaries by Qiu et al, 2011 ; Liu et al, 2012 ).…”

“…Both hypotheses have been partly tested based on biogeographic analyses of a few genera and phylogeographic examinations of some widely distributed species (see summaries by Qiu et al, 2011 ; Liu et al, 2012 ). The direct evidence for such hypotheses should derive from the times and processes of the well-delimitated sister species that may have occurred during the Pleistocene (Zanella et al, 2016 ; Wang et al, 2017 ). Although Ikeda et al ( 2012 ), Han et al ( 2016 ), and Wang et al ( 2017 ) have revealed the Pleistocene origins of a pair of endemic alpine species, two coastal wild radish lineages and four understory herbs based on population genetic data, it remains unknown whether these species or lineages were morphologically differentiated with stable distinct characters and reproductively isolated as “good species” based on the integrate species concept (Liu, 2016 ).…”

Long‐distance dispersal or postglacial contraction? Insights into disjunction between Himalaya–Hengduan Mountains and Taiwan in a cold‐adapted herbaceous genus, Triplostegia

“…In general, most temperate species retracted into smaller refugial areas during glacial periods and would experience range expansion during interglacial periods (Bueno et al, 2016;Hewitt, 1996Hewitt, , 1999Hewitt, , 2000. However, several recent studies suggested a different biogeographic history for cold-adapted coniferous species that inhabit high mountains, with range expansion during glacial periods and contraction during interglacial periods (Liu et al, 2013;Shao & Xiang, 2015;Tian, López-Pujol, Wang, Ge, & Zhang, 2010; Wang et al, 2017). Compared with lowland species, mountainous species might be more likely to survive during climatic oscillations, because short-distance vertical migrations allow them to track their optimal temperature niche (Hoorn, Mosbrugger, Mulch, & Antonelli, 2013;Sandel et al, 2011).…”

Ecological and Genetic Divergences with Gene Flow of Two Sister Species (Leucomeris decora and Nouelia insignis) Driving by Climatic Transition in Southwest China

“…decora from their common ancestor ( Li, 1995 ). Notably, population divergence or speciation possibly triggered by Pleistocene climate change has also been indicated in other flora in subtropical China, such as Pinus Yunnanensis ( Wang B. et al, 2013 ) and Dysosma versipeuis - pleiantha complex ( Wang et al, 2017 ), in which the importance of ecological factors in forming or maintaining genetic divergence was demonstrated (see discussion below). If taking the factor of environmental change associated with the tectonic event into consideration, the impact of altitude on the divergence should not be ignored, as environmental gradients associated with altitude can facilitate niche divergence ( Korner, 2007 ).…”