@article {60613, title = {Geographical and host species barriers differentially affect generalist and specialist parasite community structure in a tropical sky-island archipelago.}, journal = {Proc Biol Sci}, volume = {286}, year = {2019}, month = {2019 Jun 12}, pages = {20190439}, abstract = {

Understanding why some parasites emerge in novel host communities while others do not has broad implications for human and wildlife health. In the case of haemosporidian blood parasites, epidemic wild bird mortalities on oceanic islands have been linked to Plasmodium spp., but not genera like Haemoproteus. Indeed, Haemoproteus is absent from many oceanic islands. By contrast, birds on continental islands share long coevolutionary histories with both Plasmodium and Haemoproteus, and are thus ideal model systems to elucidate eco-evolutionary endpoints associated with these parasites in oceanic islands. Here, we examine eco-evolutionary dynamics of avian haemosporidian in the Shola sky-island archipelago of the Western Ghats, India. Our analyses reveal that compared to Plasmodium, Haemoproteus lineages were highly host-specific and diversified via co-speciation with their hosts. We show that community structure of host-generalist Plasmodium was primarily driven by geographical factors (e.g. biogeographic barriers), while that of host-specialist Haemoproteus was driven by host species barriers (e.g. phylogenetic distance). Consequently, a few host species can harbour a high diversity of Plasmodium lineages which, in turn, are capable of infecting multiple host species. These two mechanisms can act in concert to increase the risk of introduction, establishment, and emergence of novel Plasmodium lineages in island systems.

}, issn = {1471-2954}, doi = {10.1098/rspb.2019.0439}, author = {Gupta, Pooja and Vishnudas, C K and Ramakrishnan, Uma and Robin, V V and Dharmarajan, Guha} } @article {12891, title = {Two new genera of songbirds represent endemic radiations from the Shola Sky Islands of the Western Ghats, India.}, journal = {BMC Evol Biol}, volume = {17}, year = {2017}, month = {2017 Jan 23}, pages = {31}, abstract = {

BACKGROUND: A long-standing view of Indian biodiversity is that while rich in species, there are few endemics or in-situ radiations within the subcontinent. One exception is the Western Ghats biodiversity hotspot, an isolated mountain range with many endemic species. Understanding the origins of the montane-restricted species is crucial to illuminate both taxonomic and environmental history.

RESULTS: With evidence from genetic, morphometric, song, and plumage data, we show that two songbird lineages endemic to the Western Ghats montane forest each have diversified into multiple distinct species. Historically labeled as single species of widespread Asian genera, these two lineages are highly divergent and do not group with the taxa in which they were previously classified but rather are distinct early divergences in larger Asian clades of flycatchers and babblers. Here we designated two new genera, the Western Ghats shortwings as Sholicola and the laughingthrushes as Montecincla, and evaluated species-limits to reflect distinct units by revising six previously named taxa and describing one novel species. Divergence dating showed that both these montane groups split from their Himalayan relatives during the Miocene, which is coincident with a shift towards arid conditions that fragmented the previously contiguous humid forest across peninsular India and isolated these lineages in the Western Ghats. Furthermore, these two genera showed congruent patterns of diversification across the Western Ghats Sky Islands, coincident with other climatic changes.

CONCLUSION: Our study reveals the existence of two independent endemic radiations in the high montane Western Ghats or Shola Sky Islands with coincident divergence times, highlighting the role of climate in the diversification of these ancient lineages. The endemic and highly divergent nature of these previously unrecognized species underscores the dearth of knowledge about the biogeography of the Asian tropics, even for comparatively well-known groups such as birds. The substantial increase in the diversity of this region underscores the need for more rigorous systematic analysis to inform biodiversity studies and conservation efforts.

}, issn = {1471-2148}, doi = {10.1186/s12862-017-0882-6}, author = {Robin, V V and Vishnudas, C K and Gupta, Pooja and Rheindt, Frank E and Hooper, Daniel M and Ramakrishnan, Uma and Reddy, Sushma} } @article {1005, title = {Deep and wide valleys drive nested phylogeographic patterns across a montane bird community.}, journal = {Proc Biol Sci}, volume = {282}, year = {2015}, month = {2015 Jul 7}, abstract = {

Montane species distributions interrupted by valleys can lead to range fragmentation, differentiation and ultimately speciation. Paleoclimatic fluctuations may accentuate or reduce such diversification by temporally altering the extent of montane habitat and may affect species differentially. We examined how an entire montane bird community of the Western Ghats--a linear, coastal tropical mountain range--responds to topographic valleys that host different habitats. Using genetic data from 23 species (356 individuals) collected across nine locations, we examined if different species in the community reveal spatial concordance in population differentiation, and whether the timing of these divergences correlate with climatic events. Our results reveal a nested effect of valleys, with several species (10 of 23) demonstrating the oldest divergences associated with the widest and deepest valley in the mountain range, the Palghat Gap. Further, a subset of these 10 species revealed younger divergences across shallower, narrower valleys. We recovered discordant divergence times for all valley-affected montane birds, mostly in the Pleistocene, supporting the Pliestocene-pump hypotheses and highlighting the role of climatic fluctuations during this period in driving species evolution. A majority of species remain unaffected by valleys, perhaps owing to geneflow or extinction-recolonization dynamics. Studying almost the entire community allowed us to uncover a range of species{\textquoteright} responses, including some generalizable and other unpredicted patterns.

}, issn = {1471-2954}, doi = {10.1098/rspb.2015.0861}, author = {Robin, V V and Vishnudas, C K and Gupta, Pooja and Ramakrishnan, Uma} }