Can the extremely female-biased sex ratio of the social spider mites be explained by Hamilton’s local mate competition model?

Authors

  • YUKIE SATO,

    Corresponding author
    1. Laboratory of Animal Ecology, Department of Ecology and Systematics, Graduate School of Agriculture, Hokkaido University, Sapporo, Japan
    Search for more papers by this author
  • YUTAKA SAITO

    1. Laboratory of Animal Ecology, Department of Ecology and Systematics, Graduate School of Agriculture, Hokkaido University, Sapporo, Japan
    Search for more papers by this author

Yukie Sato, National Institute for Agro-Environmental Sciences, 3-1-3, Kannondai, Tsukuba, Ibaraki 305–8604, Japan. E-mail: satoyuky@affrc.go.jp

Abstract

Abstract 1. Extremely female-biased sex ratios are known in the social spider mite species, Stigmaeopsis longus and S. miscanthi. Whether Hamilton’s local mate competition (LMC) theory can explain such sex ratios was investigated.

2. Significant changes of the progeny sex ratios in the direction predicted by the LMC model were found in both species when the foundress number changed. Therefore, LMC can partly explain the skewed sex ratios in these species.

3. When the foundress number increased, the progeny sex ratio was still female biased and significantly different from the prediction of the LMC model for haplodiploidy. Relatedness between foundresses could not fully explain the female-biased sex ratios. Therefore, these results suggest that there are factors other than LMC skewing the sex ratios of these species toward female.

Ancillary