Survival costs of reproduction are mediated by parasite infection in wild Soay sheep

Jessica A. Leivesley, Luc F. Bussière, Josephine M. Pemberton, Jill Pilkington, Kenneth Wilson, Adam D. Hayward

Research output: Contribution to journalLetterpeer-review


A trade-off between current and future fitness potentially explains variation in life-history strategies. A proposed mechanism behind this is parasite-mediated reproductive costs: individuals that allocate more resources to reproduction have fewer to allocate to defence against parasites, reducing future fitness. We examined how reproduction influenced faecal egg counts (FEC) of strongyle nematodes using data collected between 1989-2008 from a wild population of Soay sheep in the St. Kilda archipelago, Scotland (741 individuals). Increased reproduction was associated with increased FEC during the lambing season: females that gave birth, and particularly those that weaned a lamb, had higher FEC than females that failed to reproduce. Structural equation modelling revealed future reproductive costs: a positive effect of reproduction on spring FEC and a negative effect on summer body weight were negatively associated with overwinter survival. Overall, we provide evidence that parasite resistance and body weight are important mediators of survival costs of reproduction.
Original languageEnglish
JournalEcology Letters
Early online date20 May 2019
Publication statusE-pub ahead of print - 20 May 2019


  • Life history
  • infection
  • immunity
  • trade-offs
  • fitness
  • peri-parturient rise
  • costs of reproduction

Fingerprint Dive into the research topics of 'Survival costs of reproduction are mediated by parasite infection in wild Soay sheep'. Together they form a unique fingerprint.

Cite this