Browsing by Author "Altmann, Jeanne"
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Item Open Access A comparison of dominance rank metrics reveals multiple competitive landscapes in an animal society.(Proceedings. Biological sciences, 2020-09-09) Levy, Emily J; Zipple, Matthew N; McLean, Emily; Campos, Fernando A; Dasari, Mauna; Fogel, Arielle S; Franz, Mathias; Gesquiere, Laurence R; Gordon, Jacob B; Grieneisen, Laura; Habig, Bobby; Jansen, David J; Learn, Niki H; Weibel, Chelsea J; Altmann, Jeanne; Alberts, Susan C; Archie, Elizabeth AAcross group-living animals, linear dominance hierarchies lead to disparities in access to resources, health outcomes and reproductive performance. Studies of how dominance rank predicts these traits typically employ one of several dominance rank metrics without examining the assumptions each metric makes about its underlying competitive processes. Here, we compare the ability of two dominance rank metrics-simple ordinal rank and proportional or 'standardized' rank-to predict 20 traits in a wild baboon population in Amboseli, Kenya. We propose that simple ordinal rank best predicts traits when competition is density-dependent, whereas proportional rank best predicts traits when competition is density-independent. We found that for 75% of traits (15/20), one rank metric performed better than the other. Strikingly, all male traits were best predicted by simple ordinal rank, whereas female traits were evenly split between proportional and simple ordinal rank. Hence, male and female traits are shaped by different competitive processes: males are largely driven by density-dependent resource access (e.g. access to oestrous females), whereas females are shaped by both density-independent (e.g. distributed food resources) and density-dependent resource access. This method of comparing how different rank metrics predict traits can be used to distinguish between different competitive processes operating in animal societies.Item Open Access Higher dominance rank is associated with lower glucocorticoids in wild female baboons: A rank metric comparison.(Hormones and behavior, 2020-08-22) Levy, Emily J; Gesquiere, Laurence R; McLean, Emily; Franz, Mathias; Warutere, J Kinyua; Sayialel, Serah N; Mututua, Raphael S; Wango, Tim L; Oudu, Vivian K; Altmann, Jeanne; Archie, Elizabeth A; Alberts, Susan CIn vertebrates, glucocorticoid secretion occurs in response to energetic and psychosocial stressors that trigger the hypothalamic-pituitary-adrenal (HPA) axis. Measuring glucocorticoid concentrations can therefore shed light on the stressors associated with different social and environmental variables, including dominance rank. Using 14,172 fecal samples from 237 wild female baboons, we test the hypothesis that high-ranking females experience fewer psychosocial and/or energetic stressors than lower-ranking females. We predicted that high-ranking females would have lower fecal glucocorticoid (fGC) concentrations than low-ranking females. Because dominance rank can be measured in multiple ways, we employ an information theoretic approach to compare 5 different measures of rank as predictors of fGC concentrations: ordinal rank; proportional rank; Elo rating; and two approaches to categorical ranking (alpha vs non-alpha and high-middle-low). Our hypothesis was supported, but it was also too simplistic. We found that alpha females exhibited substantially lower fGCs than other females (typical reduction = 8.2%). If we used proportional rank instead of alpha versus non-alpha status in the model, we observed a weak effect of rank such that fGCs rose 4.2% from the highest- to lowest-ranking female in the hierarchy. Models using ordinal rank, Elo rating, or high-middle-low categories alone failed to explain variation in female fGCs. Our findings shed new light on the association between dominance rank and the stress response, the competitive landscape of female baboons as compared to males, and the assumptions inherent in a researcher's choice of rank metric.Item Open Access Low demographic variability in wild primate populations: fitness impacts of variation, covariation, and serial correlation in vital rates.(Am Nat, 2011-01) Morris, William F; Altmann, Jeanne; Brockman, Diane K; Cords, Marina; Fedigan, Linda M; Pusey, Anne E; Stoinski, Tara S; Bronikowski, Anne M; Alberts, Susan C; Strier, Karen BIn a stochastic environment, long-term fitness can be influenced by variation, covariation, and serial correlation in vital rates (survival and fertility). Yet no study of an animal population has parsed the contributions of these three aspects of variability to long-term fitness. We do so using a unique database that includes complete life-history information for wild-living individuals of seven primate species that have been the subjects of long-term (22-45 years) behavioral studies. Overall, the estimated levels of vital rate variation had only minor effects on long-term fitness, and the effects of vital rate covariation and serial correlation were even weaker. To explore why, we compared estimated variances of adult survival in primates with values for other vertebrates in the literature and found that adult survival is significantly less variable in primates than it is in the other vertebrates. Finally, we tested the prediction that adult survival, because it more strongly influences fitness in a constant environment, will be less variable than newborn survival, and we found only mixed support for the prediction. Our results suggest that wild primates may be buffered against detrimental fitness effects of environmental stochasticity by their highly developed cognitive abilities, social networks, and broad, flexible diets.Item Open Access The emergence of longevous populations.(Proc Natl Acad Sci U S A, 2016-11-29) Colchero, Fernando; Rau, Roland; Jones, Owen R; Barthold, Julia A; Conde, Dalia A; Lenart, Adam; Nemeth, Laszlo; Scheuerlein, Alexander; Schoeley, Jonas; Torres, Catalina; Zarulli, Virginia; Altmann, Jeanne; Brockman, Diane K; Bronikowski, Anne M; Fedigan, Linda M; Pusey, Anne E; Stoinski, Tara S; Strier, Karen B; Baudisch, Annette; Alberts, Susan C; Vaupel, James WThe human lifespan has traversed a long evolutionary and historical path, from short-lived primate ancestors to contemporary Japan, Sweden, and other longevity frontrunners. Analyzing this trajectory is crucial for understanding biological and sociocultural processes that determine the span of life. Here we reveal a fundamental regularity. Two straight lines describe the joint rise of life expectancy and lifespan equality: one for primates and the second one over the full range of human experience from average lifespans as low as 2 y during mortality crises to more than 87 y for Japanese women today. Across the primate order and across human populations, the lives of females tend to be longer and less variable than the lives of males, suggesting deep evolutionary roots to the male disadvantage. Our findings cast fresh light on primate evolution and human history, opening directions for research on inequality, sociality, and aging.