Sex-biased dispersal and the speed of two-sex invasions

Tom E X Miller, Allison K. Shaw, Brian D. Inouye, Michael G. Neubert

Research output: Contribution to journalArticlepeer-review

49 Scopus citations


Population models that combine demography and dispersal are important tools for forecasting the spatial spread of biological invasions. Current models describe the dynamics of only one sex (typically females). Such models cannot account for the sex-related biases in dispersal and mating behavior that are typical of many animal species. In this article, we construct a two-sex integrodifference equation model that overcomes these limitations. We derive an explicit formula for the invasion speed from the model and use it to show that sex-biased dispersal may significantly increase or decrease the invasion speed by skewing the operational sex ratio at the invasion's low-density leading edge. Which of these possible outcomes occurs depends sensitively on complex interactions among the direction of dispersal bias, the magnitude of bias, and the relative contributions of females and males to local population growth.

Original languageEnglish (US)
Pages (from-to)549-561
Number of pages13
JournalAmerican Naturalist
Issue number5
StatePublished - May 2011

Bibliographical note

Copyright 2011 Elsevier B.V., All rights reserved.


  • Integrodifference equations
  • Invasion speed
  • Marriage squeeze
  • Mating functions
  • Sex-biased dispersal
  • Spatial spread

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