Functional diversity of Himalayan bat communities declines at high elevation without the loss of phylogenetic diversity

Ram Mohan,Christian C. Voigt,Viktoriia Radchuk,Rohit Chakravarty,Anand Krishnan

doi:10.1038/s41598-021-01939-3

Abstract

Species richness exhibits well-known patterns across elevational gradients in various taxa, but represents only one aspect of quantifying biodiversity patterns. Functional and phylogenetic diversity have received much less attention, particularly for vertebrate taxa. There is still a limited understanding of how functional, phylogenetic and taxonomic diversity change in concert across large gradients of elevation. Here, we focused on the Himalaya—representing the largest elevational gradients in the world—to investigate the patterns of taxonomic, functional and phylogenetic diversity in a bat assemblage. Combining field data on species occurrence, relative abundance, and functional traits with measures of phylogenetic diversity, we found that bat species richness and functional diversity declined at high elevation but phylogenetic diversity remained unchanged. At the lowest elevation, we observed low functional dispersion despite high species and functional richness, suggesting a niche packing mechanism. The decline in functional richness, dispersion, and divergence at the highest elevation is consistent with patterns observed due to environmental filtering. These patterns are driven by the absence of rhinolophid bats, four congeners with extreme trait values. Our data, some of the first on mammals from the Himalayan region, suggest that in bat assemblages with relatively high species diversity, phylogenetic diversity may not be a substitute to measure functional diversity.

Highlights

Benign environmental conditions and high diversity, because each species specializes to its specific ecological n iche[10,13]
25′–30° 41′ N, 78° 55′–79° 22′ E), located in Uttarakhand state in the western Himalayas of India. This sanctuary covers a broad elevational gradient from 1400 to 4000 m above sea level (Fig. 1), with corresponding changes in habitat types: from Himalayan moist temperate forests dominated by Quercus spp. at low elevations, to sub-alpine forests dominated by Rhododendron spp. and alpine meadows at high e levations[34]
We found no significant effect of location (F = 0.44, df = 3, p = 0.73), year (F = 0.95, df = 1, p = 0.34) and habitat type (F = 1.47, df = 2, p = 0.25) on the mean species detection probability

Summary

Introduction

Benign environmental conditions and high diversity (typically low elevations in mountains), because each species specializes to its specific ecological n iche[10,13]. Observing the patterns of taxonomic, functional and phylogenetic diversity in concert allows us to infer the mechanisms behind community s tructuring[13,16]. Previous trait-based and phylogenetic studies of bats along elevational gradients have returned inconsistent results. The only study that investigated this aspect of diversity found an increase in phylogenetic dispersion above 2500 m4. These inconsistencies highlight the differences among mountains and regional species pools necessitating more studies across the world if we are to obtain a general coherent picture of how bat diversity changes with elevational gradients. We investigated the variation of taxonomic, functional and phylogenetic diversity of bats across a 2000 m elevational gradient in the Himalaya. Our study provides valuable insight on community composition across a Himalayan elevational gradient

Methods

Results

Conclusion