Extinction and time help drive the marine-terrestrial biodiversity gradient: is the ocean a deathtrap?

Elizabeth C. Miller, John J. Wiens

Research output: Contribution to journalLetterpeer-review

22 Scopus citations


The marine-terrestrial richness gradient is among Earth's most dramatic biodiversity patterns, but its causes remain poorly understood. Here, we analyse detailed phylogenies of amniote clades, paleontological data and simulations to reveal the mechanisms underlying low marine richness, emphasising speciation, extinction and colonisation. We show that differences in diversification rates (speciation minus extinction) between habitats are often weak and inconsistent with observed richness patterns. Instead, the richness gradient is explained by limited time for speciation in marine habitats, since all extant marine clades are relatively young. Paleontological data show that older marine invasions have consistently ended in extinction. Simulations show that marine extinctions help drive the pattern of young, depauperate marine clades. This role for extinction is not discernible from molecular phylogenies alone, and not predicted by most previously hypothesised explanations for this gradient. Our results have important implications for the marine-terrestrial biodiversity gradient, and studies of biodiversity gradients in general.

Original languageEnglish (US)
Pages (from-to)911-921
Number of pages11
JournalEcology letters
Issue number7
StatePublished - Jul 2017


  • Amniotes
  • diversification rates
  • extinction
  • marine-terrestrial gradient
  • species richness
  • time-for-speciation

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics


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