Deep biogeographic barriers explain divergent global vertebrate communities

Area of Science:

• Ecology
• Biogeography
• Evolutionary Biology

Background:

• Biogeographic history shapes regional biodiversity, but the impact of isolation degree on community diversity remains unclear.
• Traditional biogeographic analyses treat regions discretely, overlooking varying degrees of shared evolutionary history among species assemblages.

Purpose of the Study:

• To investigate how biogeographic isolation influences taxonomic and functional diversity in global mammal and bird assemblages.
• To utilize phylobetadiversity, a continuous measure of biogeographic distance, to quantify the effect of isolation.

Main Methods:

• Analysis of taxonomic and functional diversity in global mammal and bird assemblages.
• Application of phylobetadiversity to measure biogeographic isolation.
• Comparison of diversity patterns predicted by isolation versus environmental factors.

Main Results:

• Environmental factors generally predict biodiversity better than isolation, particularly for birds.
• Mammals in highly isolated regions (e.g., Australia, Madagascar) exhibit lower diversity than predicted by environment alone, with unique functional traits.
• Neotropical bat assemblages show greater functional diversity than Paleotropical ones, reflecting long-term isolated evolutionary trajectories.

Conclusions:

• Long-standing biogeographic barriers significantly drive divergent diversity patterns, creating unique assemblages.
• While environmental determinism is a primary driver of global diversity, biogeographic isolation introduces distinct evolutionary pathways and diversity outcomes.