A minimal model for the latitudinal diversity gradient suggests a dominant role for ecological limits

Research output: Contribution to journalArticle

Abstract

The latitudinal diversity gradient (LDG) is one of Earth’s most iconic biodiversity patterns and still one of the most debated. Explanations for the LDG are often categorized into three broad pathways in which the diversity gradient is created by (1) differential diversification rates, (2) differential carrying capacities (ecological limits), or (3) differential time to accumulate species across latitude. Support for these pathways has, however, been mostly verbally expressed. Here, we present a minimal model to clarify the essential assumptions of the three pathways and explore the sensitivity of diversity dynamics to these pathways. We find that an LDG arises most easily from a gradient in ecological limits compared with a gradient in the time for species accumulation or diversification rate in most modeled scenarios. Differential diversification rates create a stronger LDG than ecological limits only when speciation and dispersal rates are low, but then the predicted LDG seems weaker than the observed LDG. Moreover, range dynamics may reduce an LDG created by a gradient in diversification rates or time for species accumulation, but they cannot reduce an LDG induced by differential ecological limits. We conclude that our simple model provides a null prediction for the effectiveness of the three LDG pathways and can thus aid discussions about the causal mechanisms underlying the LDG or motivate more complex models to confirm or falsify our findings.

Details

Authors
  • Rampal S. Etienne
  • Juliano Sarmento Cabral
  • Oskar Hagen
  • Florian Hartig
  • Allen H. Hurlbert
  • Loïc Pellissier
  • Mikael Pontarp
  • David Storch
Organisations
External organisations
  • University of Groningen
  • Julius Maximilian University of Würzburg
  • Swiss Federal Institute for Forest, Snow and Landscape Research
  • ETH Zürich
  • University of Regensburg
  • University of North Carolina
  • Charles University in Prague
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Biological Sciences

Keywords

  • Dispersal, Diversification, Ecological limits, Extinction, Latitudinal diversity gradient, Speciation
Original languageEnglish
JournalAmerican Naturalist
Publication statusE-pub ahead of print - 2019
Publication categoryResearch
Peer-reviewedYes