Get access

LARGE POPULATION SIZE PREDICTS THE DISTRIBUTION OF ASEXUALITY IN SCALE INSECTS

Authors

  • Laura Ross,

    1. Graduate Program in Organismic and Evolutionary Biology, Department of Biology, University of Massachusetts, Amherst, Massachusetts 01003
    2. Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, United Kingdom
    3. E-mail: laura.ross@zoo.ox.ac.uk
    Search for more papers by this author
    • These authors contributed equally to this manuscript.

  • Nate B Hardy,

    1. Cleveland Museum of Natural History, 1 Wade Oval Drive, Cleveland, Ohio 44106
    Search for more papers by this author
    • These authors contributed equally to this manuscript.

  • Akiko Okusu,

    1. Graduate Program in Organismic and Evolutionary Biology, Department of Biology, University of Massachusetts, Amherst, Massachusetts 01003
    Search for more papers by this author
  • Benjamin B Normark

    1. Graduate Program in Organismic and Evolutionary Biology, Department of Biology, University of Massachusetts, Amherst, Massachusetts 01003
    Search for more papers by this author

Abstract

Understanding why some organisms reproduce by sexual reproduction while others can reproduce asexually remains an important unsolved problem in evolutionary biology. Simple demography suggests that asexuals should outcompete sexually reproducing organisms, because of their higher intrinsic rate of increase. However, the majority of multicellular organisms have sexual reproduction. The widely accepted explanation for this apparent contradiction is that asexual lineages have a higher extinction rate. A number of models have indicated that population size might play a crucial role in the evolution of asexuality. The strength of processes that lead to extinction of asexual species is reduced when population sizes get very large, so that the long-term advantage of sexual over asexual reproduction may become negligible. Here, we use a comparative approach using scale insects (Coccoidea, Hemiptera) to show that asexuality is indeed more common in species with larger population density and geographic distribution and we also show that asexual species tend to be more polyphagous. We discuss the implication of our findings for previously observed patterns of asexuality in agricultural pests.

Get access to the full text of this article

Ancillary