MOLECULAR PHYLOGENY AND COMPARATIVE BIOGEOGRAPHY OF OWLETS OF INDIA

Abstract

Geographical ranges of species are a function of the interplay between ecology and evolutionary history. To understand range dynamics of co-distributed species, it is necessary to understand their evolutionary biogeography and ecology. The Endangered Forest Owlet (Heteroglaux blewitti) is a highly range-restricted species and is co-distributed with the widespread Spotted Owlet (Athene brama) and Jungle Owlet (Glaucidium radiatum) in India. The range of Spotted Owlet overlaps with the Eurasian Little Owl (Athene noctua). All four owlets show similar morphology and habits. To understand, processes underlying the nested pattern in the geographical distribution of the co-distributed owls, I used phylogenetic analysis to decipher their evolutionary biogeography, followed by past-projected Climatic Niche Models (CNMs) to understand the responses of the species to paleoclimate with respect to current time. I also modeled the ecological niche of Forest Owlet, incorporating remotely-sensed climate and vegetation data and topography, identified conservation priority areas, and future-projected the niche of Forest Owlet to 2050 to understand future threats to the species. I performed preliminary genetic analysis of a Forest Owlet population sampled from Madhya Pradesh. Results of the phylogenetic analysis showed that H. blewitti is not sister to A. brama, but nested within the Athene clade. H. blewitti, as well as other Athene members, diverged during Plio-Pleistocene boundary (3-5 Ma), possibly as a response to the changing climate. Past-projected CNMs showed that the suitable niche areas for all the owlets underwent cycles of expansion and reduction or a gradual expansion or reduction since the Last Interglacial (~120 Ka), and were nested in climatically stable areas. Forest Owlet niche models (ENMs) constructed using current climate, topography, and vegetation data, which were field-validated, resulted in identifying niche clusters for Forest Owlet in central India. When the ENMs were projected to future climate-change scenarios, reduction and shift in the niche extent were observed, indicating that future climate-change is going to impact the range of Forest Owlet severely. The genetic analysis of Forest Owlet individuals sampled from Madhya Pradesh population revealed low allelic diversity and high sharing of alleles. The results presented here underscore the need for basic research on endangered and co-distributed species to generate information that can aid conservation and form the basis of research recommendations such as deep phylogeny reconstruction, population connectivity and occupancy studies on the species.