Dr. Amy Lu, Asst. Professor, Dept. of Anthropology, Stony Brook University
This talk will be presented via Zoom.
Female counterstrategies to infanticide in lactating gelada females: adaptive, but not cost-free
Abstract: Adverse socioecological conditions can have pervasive effects on health and fitness. For mothers, adverse conditions can trigger cost-cutting strategies that limit investment in reproduction. These strategies can further impact the health and fitness of current and future offspring. Geladas are an ideal species in which to investigate the intersection between maternal and offspring responses to adversity. Gelada females reside in one-male units where a “leader” male has sole reproductive access to 2-13 adult females. Males without reproductive units must challenge and depose an existing leader to gain reproductive opportunities, and such “takeover” events are known to lead to infanticide, elevated glucocorticoids (GCs), and increased injury risk for all natal individuals within the group. Takeover risk also impacts gelada female reproductive physiology: immature females accelerate reproductive maturation, gestating mothers experience fetal loss (“Bruce effect”), and lactating mothers are suspected of producing immediate signals of fertility (sex skin swellings) that deter the likelihood of infanticide. Here, we draw on over 10 years of data from the Simien Mountains Gelada Research Project to examine the potential costs and benefits associated with this presumed strategy observed in lactating females. We found that lactating gelada females that experienced a takeover produced sex skin swellings earlier than those that did not. However, females with younger infants were less likely to produce such swellings and infant age at maternal swelling was correlated with the subsequent interbirth interval, suggesting that mothers that swell earlier divest in current offspring. Finally, infants that experienced a takeover were more likely to survive when mothers produced swellings, but also when they were simply older at takeover. Taken together, our results suggest that although the production of sex skin swellings by lactating females increases infant survival in geladas, they are not cost-free and may lead to downstream developmental consequences for infants. Furthermore, mothers of the youngest gelada infants are constrained: they are less able to produce swellings, yet their infants are more likely to die of infanticide.
Meeting ID: 928 2643 6236