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1. Associations between fecal cortisol and biparental care in a pair‐living primate

   https://doi.org/10.1002/ajpa.24368  

   Corley, Margaret ; Perea‐Rodriguez, Juan Pablo ; Valeggia, Claudia ; Fernandez‐Duque, Eduardo ( July 2021 , American Journal of Physical Anthropology)

   We quantified variation in fecal cortisol across reproductive periods in Azara's owl monkeys (Aotus azarae) to examine physiological mechanisms that may facilitate biparental care. Specifically, we evaluated evidence for the explanation that owl monkeys have hormonal mechanisms to mobilize energy during periods when each sex is investing heavily in reproduction, that is, the gestation period for females and the infant care period for males.

   Between 2011 and 2015, we monitored 10 groups of Azara's owl monkeys from a wild population in Formosa, Argentina and collected fecal samples from 26 adults (13 males, 13 females). Using enzyme‐linked immunosorbent assays, we quantified fecal cortisol as a proxy for evaluating stress responses, including energetic demands, on both sexes during periods of reproduction and parental care.

   Male cortisol was lowest during periods when they were caring for young infants (<3 months) compared with periods with older infants or no infant. Female cortisol was elevated during gestation compared with other periods. Mean fecal cortisol in both males and females was lower when an infant was present compared with when females were gestating.

   Our results do not support the hypothesis that owl monkey males have elevated fecal cortisol during periods when they need to mobilize energy to provide intensive infant care. Our findings are also inconsistent with the Maternal Relief hypothesis. However, results from studies measuring fecal cortisol must be interpreted with care and alternative explanations, such as seasonal fluctuations in diet and thermoenergic demands, should be considered when drawing conclusions.

    

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2. Contexts and consequences of takeovers in hamadryas baboons: Female parity, reproductive state, and observational evidence of pregnancy loss

   https://doi.org/10.1002/ajp.22649  

   Amann, Alexis L. ; Pines, Mathew ; Swedell, Larissa ( April 2017 , American Journal of Primatology)

   The evolutionary consequences of sexual selection and sexual conflict are epitomized in the hamadryas baboon, a species characterized by strong sexual dimorphism and intense male–male competition. Hamadryas males coerce individual females into reproductively exclusive one‐male units via aggressive takeovers, and infants involved in such takeovers are at least four times more likely to be killed (or otherwise die) after takeovers compared to other times. Here we examine female reproductive state before and after takeovers to further investigate the determinants of takeovers and their impact on female reproduction. Our data set consists of 162 takeovers over a period of 20 years in a population of wild hamadryas baboons at Filoha, Ethiopia. Results show that, in contrast to their polygynandrous relatives, hamadryas males show no bias with regard to female reproductive state at the time of the takeover, but are more likely to take over nulliparous compared to multiparous females. In addition, these results reinforce previous findings demonstrating the high likelihood of infant loss after hamadryas takeovers and suggest that females may use an additional strategy of pregnancy termination to curtail investment in offspring that are very likely to die anyway. Thus, hamadryas males may target females with high future reproductive value and hamadryas females may employ counterstrategies to help mitigate the effects of sexual coercion and infanticide on their own fitness.

    

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3. Noninvasive measurement of mucosal immunity in a free‐ranging baboon population

   https://doi.org/10.1002/ajp.23093  

   Gesquiere, Laurence R. ; Habig, Bobby ; Hansen, Christina ; Li, Amanda ; Freid, Kimberly ; Learn, Niki H. ; Alberts, Susan C. ; Graham, Andrea L. ; Archie, Elizabeth A. ( January 2020 , American Journal of Primatology)

   Ecoimmunological patterns and processes remain understudied in wild primates, in part because of the lack of noninvasive methods to measure immunity. Secretory immunoglobulin A (sIgA) is the most abundant antibody present at mammalian mucosal surfaces and provides an important first line of defense against pathogens. Recent studies show that sIgA can be measured noninvasively in feces and is a good marker of mucosal immunity. Here we validated a commercial ELISA kit to measure fecal IgA in baboons, tested the robustness of its results to variation in collection and storage conditions, and developed a cost‐effective in‐house ELISA for baboon fecal IgA. Using data from the custom ELISA, we assessed the relationship between fecal IgA concentrations and gastrointestinal parasite burden, and tested how sex, age, and reproductive effort predict fecal IgA in wild baboons. We find that IgA concentrations can be measured in baboon feces using an in‐house ELISA and are highly correlated to the values obtained with a commercial kit. Fecal IgA concentrations are stable when extracts are stored for up to 22 months at −20°C. Fecal IgA concentrations were negatively correlated with parasite egg counts (Trichuris trichiura), but not parasite richness. Fecal IgA did not vary between the sexes, but for males, concentrations were higher in adults versus adolescents. Lactating females had significantly lower fecal IgA than pregnant females, but neither pregnant nor lactating female concentrations differed significantly from cycling females. Males who engaged in more mate‐guarding exhibited similar IgA concentrations to those who engaged in little mate‐guarding. These patterns may reflect the low energetic costs of mucosal immunity, or the complex dependence of IgA excretion on individual condition. Adding a noninvasive measure of mucosal immunity will promote a better understanding of how ecology modulates possible tradeoffs between the immune system and other energetically costly processes in the wild.

    

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4. Ecology and age, but not genetic ancestry, predict fetal loss in a wild baboon hybrid zone

   https://doi.org/10.1002/ajpa.24686  

   Fogel, Arielle S. ; Oduor, Peter O. ; Nyongesa, Albert W. ; Kimwele, Charles N. ; Alberts, Susan C. ; Archie, Elizabeth A. ; Tung, Jenny ( January 2023 , American Journal of Biological Anthropology)

   Pregnancy failure represents a major fitness cost for any mammal, particularly those with slow life histories such as primates. Here, we quantified the risk of fetal loss in wild hybrid baboons, including genetic, ecological, and demographic sources of variance. We were particularly interested in testing the hypothesis that hybridization increases fetal loss rates. Such an effect would help explain how baboons may maintain genetic and phenotypic integrity despite interspecific gene flow.

   We analyzed outcomes for 1020 pregnancies observed over 46 years in a natural yellow baboon‐anubis baboon hybrid zone. Fetal losses and live births were scored based on records of female reproductive state and the appearance of live neonates. We modeled the probability of fetal loss as a function of a female's genetic ancestry (the proportion of her genome estimated to be descended from anubis [vs. yellow] ancestors), age, number of previous fetal losses, dominance rank, group size, climate, and habitat quality using binomial mixed effects models.

   Female genetic ancestry did not predict fetal loss. Instead, the risk of fetal loss is elevated for very young and very old females. Fetal loss is most robustly predicted by ecological factors, including poor habitat quality prior to a home range shift and extreme heat during pregnancy.

   Our results suggest that gene flow between yellow and anubis baboons is not impeded by an increased risk of fetal loss for hybrid females. Instead, ecological conditions and female age are key determinants of this component of female reproductive success.

    

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5. Gestational weight change and childhood body composition trajectories from pregnancy to early adolescence

   https://doi.org/10.1002/oby.23367  

   Widen, Elizabeth M. ; Burns, Natalie ; Daniels, Michael ; Backlund, Grant ; Rickman, Rachel ; Foster, Saralyn ; Nichols, Amy R. ; Hoepner, Lori A. ; Kinsey, Eliza W. ; Ramirez‐Carvey, Judyth ; et al ( March 2022 , Obesity)

   A mother–child dyad trajectory model of weight and body composition spanning from conception to adolescence was developed to understand how early life exposures shape childhood body composition.

   African American (49.3%) and Dominican (50.7%) pregnant mothers (n= 337) were enrolled during pregnancy, and their children (47.5% female) were followed from ages 5 to 14. Gestational weight gain (GWG) was abstracted from medical records. Child weight, height, percentage body fat, and waist circumference were measured. GWG and child body composition trajectories were jointly modeled with a flexible latent class model with a class membership component that included prepregnancy BMI.

   Four prenatal and child body composition trajectory patterns were identified, and sex‐specific patterns were observed for the joint GWG–postnatal body composition trajectories with more distinct patterns among girls but not boys. Girls of mothers with high GWG across gestation had the highest BMIzscore, waist circumference, and percentage body fat trajectories from ages 5 to 14; however, boys in this high GWG group did not show similar growth patterns.

   Jointly modeled prenatal weight and child body composition trajectories showed sex‐specific patterns. Growth patterns from childhood though early adolescence appeared to be more profoundly affected by higher GWG patterns in females, suggesting sex differences in developmental programming.

    

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