Browsing by Author "Archie, Elizabeth A"

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    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 A
    Across 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.
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    Developmental plasticity research in evolution and human health: Response to commentaries.
    (Evolution, medicine, and public health, 2017-01) Lea, Amanda J; Tung, Jenny; Archie, Elizabeth A; Alberts, Susan C
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    Developmental plasticity: Bridging research in evolution and human health.
    (Evolution, medicine, and public health, 2017-01) Lea, Amanda J; Tung, Jenny; Archie, Elizabeth A; Alberts, Susan C
    Early life experiences can have profound and persistent effects on traits expressed throughout the life course, with consequences for later life behavior, disease risk, and mortality rates. The shaping of later life traits by early life environments, known as 'developmental plasticity', has been well-documented in humans and non-human animals, and has consequently captured the attention of both evolutionary biologists and researchers studying human health. Importantly, the parallel significance of developmental plasticity across multiple fields presents a timely opportunity to build a comprehensive understanding of this phenomenon. We aim to facilitate this goal by highlighting key outstanding questions shared by both evolutionary and health researchers, and by identifying theory and empirical work from both research traditions that is designed to address these questions. Specifically, we focus on: (i) evolutionary explanations for developmental plasticity, (ii) the genetics of developmental plasticity and (iii) the molecular mechanisms that mediate developmental plasticity. In each section, we emphasize the conceptual gains in human health and evolutionary biology that would follow from filling current knowledge gaps using interdisciplinary approaches. We encourage researchers interested in developmental plasticity to evaluate their own work in light of research from diverse fields, with the ultimate goal of establishing a cross-disciplinary understanding of developmental plasticity.
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    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 C
    In 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.