Environmental harshness is positively correlated with intraspecific divergence in mammals and birds

Carlos A. Botero, Roi Dor, Christy M. McCain, Rebecca J. Safran

Research output: Contribution to journalReview articlepeer-review


Life on Earth is conspicuously more diverse in the tropics. Although this intriguing geographical pattern has been linked to many biotic and abiotic factors, their relative importance and potential interactions are still poorly understood. The way in which latitudinal changes in ecological conditions influence evolutionary processes is particularly controversial, as there is evidence for both a positive and a negative latitudinal gradient in speciation rates. Here, we identify and address some methodological issues (how patterns are analysed and how latitude is quantified) that could lead to such conflicting results. To address these issues, we assemble a comprehensive data set of the environmental correlates of latitude (including climate, net primary productivity and habitat heterogeneity) and combine it with biological, historical and molecular data to explore global patterns in recent divergence events (subspeciation). Surprisingly, we find that the harsher conditions that typify temperate habitats (lower primary productivity, decreased rainfall and more variable and unpredictable temperatures) are positively correlated with greater subspecies richness in terrestrial mammals and birds. Thus, our findings indicate that intraspecific divergence is greater in regions with lower biodiversity, a pattern that is robust to both sampling variation and latitudinal biases in taxonomic knowledge. We discuss possible causal mechanisms for the link between environmental harshness and subspecies richness (faster rates of evolution, greater likelihood of range discontinuities and more opportunities for divergence) and conclude that this pattern supports recent indications that latitudinal gradients of diversity are maintained by simultaneously higher potentials for both speciation and extinction in temperate than tropical regions. See also the Perspective by Weir

Original languageEnglish
Pages (from-to)259-268
Number of pages10
JournalMolecular Ecology
Issue number2
StatePublished - Feb 2014
Externally publishedYes


  • Climate and evolution
  • Comparative biology
  • Latitudinal diversity gradients
  • Raciation
  • Subspeciation
  • Subspecies richness


Dive into the research topics of 'Environmental harshness is positively correlated with intraspecific divergence in mammals and birds'. Together they form a unique fingerprint.

Cite this