In recent times of global biodiversity crisis, documenting the distribution patterns of regional biodiversity and unravelling the drivers that shape these patterns has assumed urgent research priority. In mountains, understanding the distribution of biodiversity along elevational gradients is crucial to its conservation, restoration, and sustainable use. In the Himalaya – highest mountain range in the world – although studies focusing on the elevational distribution of higher plants (angiosperms and gymnosperms) are available, however such studies on lower plants such as pteridophytes are largely lacking. To fill this knowledge gap, here we investigate the elevational patterns of taxonomic and phylogenetic diversity of pteridophytes and their bioclimatic drivers in Jammu and Kashmir. We compiled a comprehensive dataset on 225 pteridophyte species of the study region. We divided the elevation gradient in the study region into 43 vertical bands, each with a width of 100 meters. We used regression analysis to assess the relationship of species richness (SR), standardized effect sizes of phylogenetic diversity (PDses), mean pairwise distance (MPDses), and mean nearest taxon distance (MNTDses) with the elevation. Our results revealed a mid-elevational peak in species richness and a half U-shaped curve in phylogenetic structure along the elevational gradient. We found phylogenetic clustering more or less at mid- and high-elevational bands and phylogenetic overdispersion at low-elevation bands. Taxonomic and phylogenetic ꞵ-diversity was mainly governed by species turnover component. Further, the precipitation-related climatic variables explained a greater proportion of the variation in SR compared to temperature-related variables; but converse was true for PDses, MPDses, and MNTDses, thereby indicating that niche conservatism and environmental filtering shape the composition of pteridophytes along the elevation in this Himalayan region. Overall, the findings of the present study advance our understanding about the elevational distribution patterns in pteridophytes with wide implications for ecology, evolution and biogeography of mountain biodiversity.
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