Radiation of tropical island bees and the role of phylogenetic niche conservatism as an important driver of biodiversity

James B. Dorey, Scott V C. Groom, Elisha H. Freedman, Cale S. Matthews, Olivia K. Davies, Ella J. Deans, Celina Rebolas, Mark Stevens, Michael S Y. Lee, Michael Schwarz

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)


Island biogeography explores how biodiversity in island ecosystems arises and is maintained. The topographical complexity of islands can drive speciation by providing a diversity of niches that promote adaptive radiation and speciation. However, recent studies have argued that phylogenetic niche conservatism, combined with topographical complexity and climate change, could also promote speciation if populations are episodically fragmented into climate refugia that enable allopatric speciation. Adaptive radiation and phylogenetic niche conservatism therefore both predict that topographical complexity should encourage speciation, but they differ strongly in their inferred mechanisms. Using genetic (mitochondrial DNA (mtDNA) and single-nucleotide polymorphism (SNP)) and morphological data, we show high species diversity (22 species) in an endemic clade of Fijian Homalictus bees, with most species restricted to highlands and frequently exhibiting narrow geographical ranges. Our results indicate that elevational niches have been conserved across most speciation events, contradicting expectations from an adaptive radiation model but concordant with phylogenetic niche conservatism. Climate cycles, topographical complexity, and niche conservatism could interact to shape island biodiversity. We argue that phylogenetic niche conservatism is an important driver of tropical island bee biodiversity but that this phylogenetic inertia also leads to major extinction risks for tropical ectotherms under future warming climates.

Original languageEnglish
Article number20200045
Number of pages8
JournalProceedings of The Royal Society of London Series B: Biological Sciences
Issue number1925
Publication statusPublished - 29 Apr 2020


  • adaptive radiation
  • allopatric
  • climate change
  • evolution
  • speciation
  • thermal specialist


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