Frequency Dependence and Ecological Drift Shape Coexistence of Species with Similar Niches

Erik I. Svensson, Miguel A. Gómez-Llano, Anais Rivas Torres, Hanna M. Bensch

Research output: Contribution to journalArticlepeer-review

Abstract

The coexistence of ecologically similar species might be counteracted by ecological drift and demographic stochasticity, both of which erode local diversity. With niche differentiation, species can be maintained through performance trade-offs between environments, but trade-offs are difficult to invoke for species with similar ecological niches. Such similar species might then go locally extinct due to stochastic ecological drift, but there is little empirical evidence for such processes. Previous studies have relied on biogeographical surveys and inferred process from pattern, while experimental field investigations of ecological drift are rare. Mechanisms preserving local species diversity, such as frequency dependence (e.g., rare-species advantages), can oppose local ecological drift, but the combined effects of ecological drift and such counteracting forces have seldom been investigated. Here, we investigate mechanisms between coexistence of ecologically similar but strongly sexually differentiated damselfly species (Calopteryx virgo and Calopteryx splendens). Combining field surveys, behavioral observations, experimental manipulations of species frequencies and densities, and simulation modeling, we demonstrate that species coexistence is shaped by the opposing forces of ecological drift and negative frequency dependence (rare-species advantage), generated by interference competition. Stochastic and deterministic processes therefore jointly shape coexistence. The role of negative frequency dependence in delaying the loss of ecologically similar species, such as those formed by sexual selection, should therefore be considered in community assembly, macroecology, macroevolution, and biogeography.

Original languageEnglish
Pages (from-to)691-703
JournalAmerican Naturalist
Volume191
Issue number6
Early online date2018 Jun 1
DOIs
Publication statusPublished - 2018

Subject classification (UKÄ)

  • Evolutionary Biology

Free keywords

  • ecological drift
  • frequency dependence
  • neutral theory
  • sexual selection
  • speciation
  • unified neutral theory of biodiversity

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