Mammalian Biology

, Volume 81, Issue 1, pp 61–65 | Cite as

Litter sizes of Daurian ground squirrels peak at intermediate body sizes

  • Xingrong Wan
  • Liang Liu
  • Guiming WangEmail author
  • Yongwang Guo
Original Investigation


Litter size and body size of animals may coevolve under the concomitant pressures of sexual selection, fecundity selection, and viability selection. Studies have demonstrated the positive relationship between body size and litter size, consistent with Darwin’s fecundity advantage of large body size. However, the counterbalancing selection hypothesis predicts fecundity selection would result in a positive correlation between litter size and body size initially, whereas the opposite pressure by viability selection would decrease litter size with further increasing body size beyond a threshold size. Moreover, the reproduction senescence hypothesis predicts that litter size of old, large females would decline with deteriorating body conditions. In this study, we tested the predictions of the counterbalancing selection hypothesis and the reproduction senescence hypothesis concerning the quadratic relationship between body size and litter size in Daurian ground squirrels (Spermophilus dauricus). Litter size increased initially with increasing carcass weight of females, and then decreased with further increases in carcass weight, supporting the prediction of the counterbalancing hypothesis. However, litter size was not related to body condition index of females, and body conditions improved with increasing body weight, suggesting that the reproduction senescence hypothesis alone cannot explain the observed quadratic relationship between litter size and carcass weight of female S. dauricus.


Body condition Fecundity selection Reproduction senescence Trade-off Viability selection 


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Copyright information

© Deutsche Gesellschaft für Säugetierkunde 2014

Authors and Affiliations

  • Xingrong Wan
    • 1
  • Liang Liu
    • 1
  • Guiming Wang
    • 2
    Email author
  • Yongwang Guo
    • 3
  1. 1.State Key Laboratory for Integrated Management of Pest Insects and RodentsInstitute of Zoology, Chinese Academy of SciencesBeijingChina
  2. 2.Department of Wildlife, Fisheries and Aquaculture, Mail Stop 9690Mississippi State UniversityUSA
  3. 3.National Agro-tech Extensions and Service CenterChaoyang District, BeijingChina

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