Comparative phylogeography reveals a shared impact of pleistocene environmental change in shaping genetic diversity within nine Anopheles mosquito species across the Indo-Burma biodiversity hotspot

Abstract

South-East Asia is one of the world's richest regions in terms of biodiversity. An understanding of the distribution of diversity and the factors shaping it is lacking, yet essential for identifying conservation priorities for the region's highly threatened biodiversity. Here, we take a large-scale comparative approach, combining data from nine forest-associated Anopheles mosquito species and using statistical phylogeographical methods to disentangle the effects of environmental history, species-specific ecology and random coalescent effects. Spatially explicit modelling of Pleistocene demographic history supports a common influence of environmental events in shaping the genetic diversity of all species examined, despite differences in species' mtDNA gene trees. Populations were periodically restricted to allopatric northeastern and northwestern refugia, most likely due to Pleistocene forest fragmentation. Subsequent southwards post-glacial recolonization is supported by a north-south gradient of decreasing genetic diversity. Repeated allopatric fragmentation and recolonization have led to the formation of deeply divergent geographical lineages within four species and a suture zone where these intraspecific lineages meet along the Thai-Myanmar border. A common environmental influence for this divergence was further indicated by strong support for simultaneous divergence within the same four species, dating to approximately 900 thousand years ago (kya). Differences in the geographical structuring of genetic diversity between species are probably the result of varying species' biology. The findings have important implications for conservation planning; if the refugial regions and suture zone identified here are shared by other forest taxa, the unique and high levels of genetic diversity they house will make these areas conservation priorities.

Detecting Concerted Demographic Response across Community Assemblages Using Hierarchical Approximate Bayesian Computation

“…Under this strategy, this multitaxon statistical framework makes community-level inference while accommodating coalescent, mutational, and demographic variance associated with individual species and loci (Beaumont 2010; Morgan et al 2011) and gains statistical strength from pooling data for a single analysis (Beaumont and Rannala 2004). Specifically, our multitaxon statistical framework uses hierarchical approximate Bayesian computation (hABC).…”

“…However, up to now, most hABC studies in a comparative phylogeographic context focused on studies of codivergence (Hickerson and Meyer 2008; Carnaval et al 2009; Barber and Klicka 2010; Morgan et al 2011) and local adaptation (Bazin et al 2010). The method we introduce here is the first multispecies coalescent model-based method for the demographic inference of coordinated and/or independent multipopulation expansion histories, thereby allowing large-scale inferences relevant to questions about community assembly and variable responses to future climate changes.…”

Genetic population structure of the malaria vector Anopheles baimaii in north-east India using mitochondrial DNA

“…This is in accord with NE India being the origin of all extant populations of this species [5]. A further contributing factor to this high genetic diversity may be that much of NE India has acted as a refugium for forest species during Pleistocene glacial cycles when forests were reduced and fragmented across Southeast Asia due to lower temperatures and increased aridity [[50] and refs therein]. The signal of population expansion dating to the late Pleistocene is consistent with this, as during interglacials forests and forest-dependent taxa would expand from refugial areas.…”

The genus Ectadia (Orthoptera: Phaneropteridae: Phaneropterinae) in East Asia: description of a new species, comparison of its complex song and duetting behavior with that of E. fulva and notes on the biology of E. fulva

“…It may not be so surprising to find a high number of species in this relatively small area, since Yunnan is one of the global biodiversity hotspots, well known for plant diversity (Li et al 2015, Tang 2015, although not yet so much for insects (but see e.g. Morgan et al 2011). Therefore, when we heard an unknown calling song of an Ectadia species during a joint excursion (CXL and KGH) in Yunnan, we expected to find one of these species.…”