Evolutionary Ecology

, Volume 14, Issue 3, pp 195–211

A hypothesis for the evolution of androdioecy: the joint influence of reproductive assurance and local mate competition in a metapopulation

  • John R. Pannell

DOI: 10.1023/A:1011082827809

Cite this article as:
Pannell, J.R. Evolutionary Ecology (2000) 14: 195. doi:10.1023/A:1011082827809


In a subdivided population with recurrent local extinction and re-colonisation, competition amongst related pollen or sperm to fertilise ovules or eggs (‘local mate competition’) is expected to select for female-biased sex allocation. Population turnover should also select against unisexuality in favour of self-fertile cosexuality, because males and females are unable to establish new populations on their own (‘Baker's Law’). Here I argue that androdioecy, a rare breeding system in which males co-occur with hermaphrodites, may evolve in a metapopulation under the joint action of local mate competition and Baker's Law if rates of self-fertilisation decrease with increasing population size. The hypothesis makes several predictions regarding patterns of life-history and sex allocation that are borne out by recent observations of androdioecious species in several unrelated lineages of plants and animals.

Baker's Lawcolonisationdioecydispersalextinctiongain curvegynodioecylocal mate competitionsex ratio

Copyright information

© Kluwer Academic Publishers 2000

Authors and Affiliations

  • John R. Pannell
    • 1
  1. 1.Department of Plant SciencesUniversity of OxfordOxfordUnited Kingdom