Journal article

Inbreeding and reproductive investment in the ant Formica exsecta

  • Vitikainen, Emma Department of Biological and Environmental sciences, University of Helsinki, Helsinki, Finland - Centre for Ecology and Conservation, University of Exeter, Tremough Campus, Penryn, Cornwall, UK
  • Haag-Liautard, Cathy Institute of Ecology and Evolution, University of Fribourg, Fribourg, Switzerland
  • Sundström, Liselotte Department of Biological and Environmental sciences, University of Helsinki, Helsinki, Finland
Published in:
  • Evolution. - 2011, vol. 65, no. 7, p. 2026–2037
English In social animals, inbreeding depression may manifest by compromising care or resources individuals receive from inbred group members. We studied the effects of worker inbreeding on colony productivity and investment in the ant Formica exsecta. The production of biomass decreased with increasing inbreeding, as did biomass produced per worker. Inbred colonies produced fewer gynes (unmated reproductive females), whereas the numbers of males remained unchanged. As a result, sex ratios showed increased male bias, and the fraction of workers increased among the diploid brood. Males raised in inbred colonies were smaller, whereas the weight of gynes remained unchanged. The results probably reflect a trade-off between number and quality of offspring, which is expected if the reproductive success of gynes is more dependent on their weight or condition than it is for males. As males are haploid (with the exception of abnormal diploid males produced in very low frequencies in this population), and therefore cannot be inbred themselves, the effect on their size must be mediated through the workers of the colony. We suggest the effects are caused by the inbred workers being less proficient in feeding the growing larvae. This represents a new kind of social inbreeding depression that may affect sex ratios as well as caste fate in social insects.
Faculté des sciences et de médecine
Département de Biologie
  • English
Biological sciences
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