Niche divergence corresponds to genetic differentiation within the parrot-beaked tortoise Homopus areolatus (Reptilia: Testudinidae), endemic to South Africa
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Date
2020
Journal Title
Journal ISSN
Volume Title
Publisher
Linnean Society of London
Abstract
We assessed genetic differentiation and habitat suitability for Homopus areolatus during current and Last Glacial
Maximum (LGM) conditions. The ND4 locus retrieved two monophyletic mtDNA clades with lower diversity in clade 1, in the west, than in clade 2, in the south-east. Clade 1 showed a north–south and clade 2 a west-to-east genetic divergence, and the clades co-occur in the syntaxis zone of the Cape Fold Mountains. The clades occupy distinct niches with limited overlap. Rainfall seasonality contributed most to habitat suitability, with clade 1 being restricted to winter rainfall and clade 2 to all-year rainfall regions. Precipitation variables contributed 90% and 60%, respectively, to habitat suitability of clades 1 and 2, with temperature, particularly mean temperature of the driest quarter, being= of greater importance for clade 2 than clade 1. Suitable habitat shrank from the LGM to current conditions, probably due to reduced rainfall in the west and higher temperatures in most regions. We conclude that patterns of genetic divergence are strongly associated with ecological niche divergence of H. areolatus clades. More studies are needed to assess the taxonomic status of clade 1, particularly in view of its shrinking habitat due to climate change and anthropogenic factors.
Description
Keywords
Homopus areolatus, Cape Fold Mountains, fynbos, glaciation, palaeoclimate
Citation
Hofmeyr, M. D., Ihlow, F., Fouche, P., & Daniels, S. R. (2020). Niche divergence corresponds to genetic differentiation within the parrot-beaked tortoise Homopus areolatus (Reptilia: Testudinidae), endemic to South Africa. Zoological Journal of the Linnean Society, 190(4), 1256–1273. https://doi.org/10.1093/zoolinnean/zlaa030