Volume 112, February 2016, Pages 1–11
- a Department of Ecology and Evolutionary Biology, University of California Los Angeles, Los Angeles, CA, U.S.A.
- b The Rocky Mountain Biological Laboratory, Crested Butte, CO, U.S.A.
- c Department of Biology, Mills College, Oakland, CA, U.S.A.
- Received 22 February 2015, Revised 20 March 2015, Accepted 30 September 2015, Available online 11 December 2015
- MS. number: A15-00144R2
Highlights
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- We examined the relation between rank, basal stress and reproductive success in female marmots.
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- High-ranking females had lower stress (faecal glucocorticoid metabolite, FGM) levels and larger litters.
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- However, females with the highest FGM levels were more likely to reproduce.
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- Body condition was positively associated with reproductive success.
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- In yellow-bellied marmots, FGM levels fail to mediate reproductive suppression.
The
effects of social and ecological stressors on female reproductive
success vary among species and, in mammals, previous reviews have
identified no clear patterns. However, few studies have simultaneously
examined the relation between social rank and stressors and the
relationships among rank, stressors and reproductive success. We used a
long-term data set to study free-living facultatively social
yellow-bellied marmots, Marmota flaviventris, to isolate the
relationship between female social dominance rank and faecal
glucocorticoid metabolite (FGM) levels (our measure of basal stress) in
adult females. In addition, we examined whether rank and FGM levels were
associated with reproductive success by quantifying the probability of
an individual successfully weaning a litter and, for those who did,
litter size. High-ranking females had lower FGM levels and larger
litters. However, females with the highest FGM levels were significantly
more likely to wean a litter. Importantly, body condition (as measured
by previous year's mass) was also positively associated with breeding
and with weaning larger litters. Thus, although low-ranking females
probably experienced more social stressors than high-ranking females and
although adult females often delayed their first reproduction until
they were of a sufficient mass, our results suggest that elevated
baseline FGM levels failed to mediate reproductive suppression. Perhaps,
in species like marmots that have only a single chance per year to
reproduce, reproductive suppression should be rare. These results
highlight the importance of social status, body condition and predator
abundance on determining reproductive success in highly seasonal
breeders.
Keywords
- ecological stressor;
- glucocorticoid;
- reproductive success;
- reproductive suppression;
- social rank;
- social stressor;
- yellow-bellied marmot
Copyright © 2015 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.
