Abstract # 132:

Scheduled for Friday, June 21, 2013 04:15 PM-04:30 PM: Session 18 (San Geronimo Ballroom B) Oral Presentation


CAUSES AND CONSEQUENCES OF THE "PALACE COUP": WHAT HAIR CORTISOL TELLS US ABOUT THE MATRILINEAL OVERTHROW AT THE LCE FIELD STATION

M. A. Novak and J. S. Meyer
Department of Psychology, University of Massachusetts Amherst, Amherst, MA 01003
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     In March 2009, a rare a matrilineal overthrow in the rhesus monkey (Macaca mulatta) troop occurred at the LCE’s 5-acre field station, whereby the second-ranking matriline deposed the top-ranking matriline. In an analysis of data collected in the years surrounding the overthrow (N=57-107), we examined relationships between population density, chronic stress as assessed by hair cortisol concentrations (HCC), number of severe fight wounds, and infant loss in each year from 2007-2010. Repeated measures ANOVA revealed that HCC increased from 2007 to 2008 (the first time the troop ever exceeded 100 individuals), declined in 2009 (concomitant with the removal of Matriline 1 after the overthrow), and declined again in 2010 as population control measures were enacted (F(1,26)=7.08,p<0.001). Pearson correlation revealed a strong association between population density and average hair cortisol (r2=0.924,p<0.009) across years. Total severe fight wounds (33) and infant mortality (41%) both peaked during the overthrow in 2009, six months after the maximum population was recorded. These two values also decreased in response to population control, and were strongly correlated across years (r2=0.958,p=0.001). HCC declined for the matriarchs of the second-ranking matriline after they assumed dominance from February 2009-February 2010 (Z=-2.02,p=0.043), but remained unchanged for matriarchs uninvolved in the overthrow. These findings indicate that population density influences chronic stress levels, and that these factors may later confer fitness consequences in a semi free-ranging population.