The endocrinology of pregnancy and fetal loss in wild baboons

Self Cite

107

Environmental stressors impact physiology and behavior in many species of animals. These effects are partly mediated through changing concentrations of glucocorticoids, which also vary with reproductive state and social conditions. Prior research has focused largely on seasonal breeders, but the close temporal linkage between season and reproductive state in these species hinders ability to disentangle environmental effects from those of the animal's reproductive status. Here we assessed the effects of environmental challenges on the fecal glucocorticoid (fGC) levels of non-seasonal breeders, female baboons (Papio cynocephalus) of Amboseli, Kenya. Amboseli is characterized by a long dry season, during which food and water become scarce, and by extreme temperatures above 40°C in the shade during some months of the year. We found that after accounting for female reproductive status and individual variability, females exhibited higher fGC levels during the dry season than during the wet season. Further, during the wet season, fGC levels were higher in months of high average daily maximum temperatures. During the dry season, fGC levels were elevated both in hotter months and in months during which the baboons spent a relatively high proportion of time feeding. In spite of these stressors, female baboons reproduce during all months of the year in Amboseli, unlike most other mammals in this environment. This may be attributable to their extreme adaptability, specifically their diversified diet, and their ability to modify their behavior, including their activity profiles.

Section: Individual and Reproductive State Differences In Fgcmentioning

confidence: 94%

Section: Female Reproductive Statementioning

confidence: 99%

Coping with a challenging environment: Effects of seasonal variability and reproductive status on glucocorticoid concentrations of female baboons (Papio cynocephalus)

Gesquiere

Khan

Shek

et al. 2008

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107

“…External stressors are known to affect females differently in different reproductive states depending upon the relative risk the stressor imposes (French et al 2004;Engh et al 2006b;Beehner et al 2006;Power & Schulkin 2006). In the Okavango, dominant immigrant males are often infanticidal, Cheney et al 2004) and therefore pose a significant threat to lactating females.…”

Section: Events During the Time Of Male Rank Instabilitymentioning

confidence: 99%

Focused grooming networks and stress alleviation in wild female baboons

Wittig

Crockford

Lehmann

et al. 2008

242

215

We examine the relationship between glucocorticoid (GC) levels and grooming behavior in wild female baboons during a period of instability in the alpha male rank position. All females' GC levels rose significantly at the onset of the unstable period, though levels in females who were at lower risk of infanticide began to decrease sooner in the following weeks. Three factors suggest that females relied on a focused grooming network as a coping mechanism to alleviate stress. First, all females' grooming networks became less diverse in the weeks following the initial upheaval. Second, females whose grooming had already focused on a few predictable partners showed a less dramatic rise in GC levels than females whose grooming network had been more diverse. Third, females who contracted their grooming network the most experienced a greater decrease in GC levels in the following week. We conclude that close bonds with a few preferred partners allow female baboons to alleviate the stress associated with social instability.

“…Pregnancy assignment was made based on near-daily records of each female's reproductive cycles, including sex-skin size and condition and observed menstruation, a long-standing observational method that has recently been validated through hormonal analysis (see Beehner et al, 2006). In this dataset, parity ranged from 1 to 10 (median 4; see Table 1), and none of the subadults had the same mother.…”

Section: Maternal Reproductive Experiencementioning

confidence: 99%

“…Fecal sample collection, storage and extraction were done as described previously (Beehner et al, 2006;Gesquiere et al, 2005;Khan et al 2002). Fecal GC was quantified using the ICN Corticosterone RIA kit for Rats and Mice, ICN Biomedicals, Inc.Costa Mesa.…”

Section: Fecal Glucocorticoid Concentration (Fgc)mentioning

confidence: 99%

Persistence of maternal effects in baboons: Mother's dominance rank at son's conception predicts stress hormone levels in subadult males

Onyango

Gesquiere

Wango

et al. 2008

Self Cite

Dominance status and reproductive experience are maternal characteristics that affect offspring traits in diverse taxa, including some cercopithecine primates. Maternal effects of this sort are widespread and are sources of variability in offspring fitness. We tested the hypothesis that maternal dominance rank and reproductive experience as well as a male's own age and dominance rank predicted chronic fecal glucocorticoid (fGC) concentrations in 17 subadult wild male baboons, Papio cynocephalus (median age 6.5 years), in the Amboseli basin, Kenya. Among these variables, maternal dominance rank at a subadult male's conception was the sole significant predictor of the male's fGC and accounted for 42% of fGC variance; sons of lower ranking mothers had higher fGC than did those of high ranking mothers. This result is striking because subadult male baboons are approximately 4-6 years past the period of infant dependence on their mothers, and are larger than and dominant to all adult females. In addition, many males of this age have survived their mothers' death. Consequently, the influence of maternal dominance rank persisted well beyond the stage at which direct maternal influence on sons is likely. Persistence of these major maternal influences from the perinatal period may signal organizational effects of mothers on sons' HPA axis. Although shortterm, acute, elevations in GC are part of adaptive responses to challenges such as predators and other emergencies, chronically elevated GC are often associated with stress-related pathologies and, thereby, adverse effects on fitness components.