Range-restricted species generally have specific niche requirements and may often have unique evolutionary histories. Unfortunately, many of these species severely lack basic research, resulting in poor conservation strategies. The phylogenetic relationship of the Critically Endangered Forest Owlet Heteroglaux blewitti has been the subject of a century-old debate. The current classifications based on non-phylogenetic comparisons of morphology place the small owls of Asia into three genera, namely, Athene, Glaucidium, and Heteroglaux. Based on morphological and anatomical data, H. blewitti has been alternatively hypothesized to belong within Athene, Glaucidium, or its own monotypic genus Heteroglaux. To test these competing hypotheses, we sequenced six loci (~4300 bp data) and performed phylogenetic analyses of owlets. Mitochondrial and nuclear trees were not congruent in their placement of H. blewitti. However, both mitochondrial and nuclear combined datasets showed strong statistical support with high maximum likelihood bootstrap (>/ = 90) and Bayesian posterior probability values (>/ = 0.98) for H. blewitti being nested in the currently recognized Athene group, but not sister to Indian A. brama. The divergence of H. blewitti from its sister taxa was between 4.3 and 5.7 Ma coinciding with a period of drastic climatic changes in the Indian subcontinent. This study presented the first genetic analysis of H. blewitti, a Critically Endangered species, and addressed the long debate on the relationships of the Athene-Heteroglaux-Glaucidium complex. We recommend further studies with more data and complete taxon sampling to understand the biogeography of Indian Athene species.
Aim
The nested pattern in the geographical distribution of three Indian owlets, resulting in a gradient of endemicity, is hypothesized to be an impact of historical climate change. In current time, the Forest Owlet
Athene blewitti
is endemic to central India, and its range is encompassed within the ranges of the Jungle Owlet
Glaucidium radiatum
(distributed through South Asia) and Spotted Owlet
Athene brama
(distributed through Iran, South and Southeast Asia). Another phylogenetically close species, Little Owl
Athene noctua,
which is largely Palearctic in distribution, is hypothesized to have undergone severe range reduction during the Last Glacial Maximum, showing a postglacial expansion. The present study tests hypotheses on the possible role of Quaternary climatic fluctuations in shaping geographical ranges of owlets.
Methods
We used primary field observations, open access data, and climatic niche modeling to construct climatic niches of four owlets for four periods, the Last Interglacial (~120–140 Ka), Last Glacial Maximum (~22 Ka), Mid‐Holocene (~6 Ka), and Current (1960–1990). We performed climatic niche extent, breadth, and overlap analyses and tested if climatically suitable areas for owlets are nested in a relatively stable climate.
Results
Climatically suitable areas for all owlets examined underwent cycles of expansion and reduction or a gradual expansion or reduction since the Last Interglacial. The Indian owlets show significant climatic niche overlap in the current period. Climatically suitable areas for Little Owl shifted southwards during the Last Glacial Maximum and expanded northwards in the postglaciation period. For each owlet, the modeled climatic niches were nested in climatically stable areas.
Main Conclusions
The study highlights the impact of Quaternary climate change in shaping the present distribution of owlets. This is relevant to the current scenario of climate change and global warming and can help inform conservation strategies, especially for the extremely range‐restricted Forest Owlet.
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