Reproductive rate, not dominance status, affects fecal glucocorticoid levels in breeding female meerkats.
Glucocorticoid hormones (GCs) have been studied intensively to understand the associations between physiological stress and reproductive skew in animal societies. However, we have little appreciation of the range of either natural levels within and among individuals, or the associations among dominance status, reproductive rate and GCs levels during breeding. To address these shortcomings, we examined variation in fecal glucocorticoid metabolites (fGC) during breeding periods in free-ranging female meerkats (Suricata suricatta) over 11 years. The vast majority of variation in fGC levels was found within breeding events by the same female (~87%), with the remaining variation arising among breeding events and among females. Concentrations of fGC generally tripled as pregnancy progressed. However, females with a high reproductive rate, defined as those conceiving within a month following parturition (mean = 9 days postpartum), showed significant reductions in fGC in the final 2 weeks before parturition. Despite these reductions, females with a high reproductive rate had higher fGC levels at conception of the following litter than those breeding at a low rate. After controlling for the higher reproductive rate of dominants, we found no association between levels of fGC and either age or dominance status. Our results suggest that one should be cautious about interpreting associations between dominance status, reproductive skew and GCs levels, without knowledge of the natural variation in GCs levels within and among females.
Département de biologie, Université de Sherbrooke, Sherbrooke J1K 2R1, Canada. m-f.barrette@usherbrooke.ca
Marie-France
MF
Barrette
Steven L
SL
Monfort
Marco
M
Festa-Bianchet
Tim H
TH
Clutton-Brock
Andrew F
AF
Russell
D000375:Aging / Q000502:physiology; D000818:Animals; D001723:Birth Rate; D001835:Body Weight / Q000502:physiology; D005243:Feces / Q000737:chemistry*; D005260:Female; D005938:Glucocorticoids / Q000737:chemistry / Q000378:metabolism*; D008988:Herpestidae / Q000502:physiology*; D008297:Male; D036801:Parturition; D011247:Pregnancy; D012098:Reproduction / Q000502:physiology*; D012726:Sexual Behavior, Animal / Q000502:physiology; D012930:Social Dominance
D005938:Glucocorticoids