Age and sex‐specific mortality of wild and captive populations of a monogamous pair‐bonded primate (Aotus azarae)

Abstract

In polygynous primates, a greater reproductive variance in males have been linked to their reduced life expectancy relative to females. The mortality patterns of monogamous pair-bonded primates, however, are less clear. We analyzed the sex differences in mortality within wild (NMales = 70, NFemales = 73) and captive (NMales = 25, NFemales = 29) populations of Azara’s owl monkeys (Aotus azarae), a socially and genetically monogamous primate exhibiting biparental care. We used Bayesian Survival Trajectory Analysis (BaSTA) to test age-dependent models of mortality. The wild and captive populations were best fit by the logistic and Gompertz models, respectively, implying greater heterogeneity in the wild environment likely due to harsher conditions. We found that age patterns of mortality were similar between the sexes in both populations. We calculated life expectancy and disparity, the latter a measure of the steepness of senescence, for both sexes in each population. Males and females had similar life expectancies in both populations; the wild population overall having a shorter life expectancy than the captive one. Furthermore, captive females had a reduced life disparity relative to captive males and to both sexes in the wild. We interpret this pattern in light of the hazards associated with reproduction. In captivity, where reproduction is intensely managed, the risks associated with gestation and birth are tempered so that there is a reduction in the likelihood of captive females dying prematurely, decreasing their overall life disparity.

Comparative analyses of longevity and senescence reveal variable survival benefits of living in zoos across mammals

“…However, zoo animals may be subject to behavioral deficits6. While an increasing number of comparative studies have demonstrated species-specific differences in the response to zoo-conditions789, and a few species-specific comparisons of survival metrics between free-ranging and captive specimens have been published1011, large-scale inter-specific comparisons of captive and free-ranging populations have not yet been performed. Indeed, it is probably difficult to gather accurate demographic estimates in these two contrasted environments for a large range of species.…”

“Monogamy” in Primates: Variability, Trends, and Synthesis: Introduction to special issue on Primate Monogamy

“…Concomitantly, these contributions highlight the need for more nuanced and precise descriptors of primate social behavior and the evolutionary outcomes of these behaviors. Regardless of the amount of social variability, simple explanations for the appearance and maintenance of monogamy are not supported by the empirical data [Fernandez-Duque, this issue]; and increasingly quantitative approaches [Fernandez-Duque, this issue; Carp, Rothwell et al, this issue] that focus on the drivers of social organization will provide the next breakthroughs in our understanding of primate mating and breeding strategies. The papers collected herein give clear routes for future research on: more extensive field studies, more attention to the role of phenotypic plasticity in understanding the evolution of monogamy, more quantification and predictive models, and the importance of integrating lab and field studies.…”

“…Large colony databases, spanning decades of study and generations of animals, are now available to examine life history parameters in different species [Larson et al, this issue]. Controlled laboratory conditions and standardized tests have allowed us to ask probing questions, especially regarding the socioemotional aspects of monogamy [Mendoza and Mason, 1986].…”

“…Larson and colleagues [this issue] compare life history parameters in populations of Azara's owl monkeys ( Aotus azarae) from the Argentinian chaco and the Keeling Center for Comparative Medicine and Research in Bastrop, TX. In both populations, males and females lived for similar lengths of time, although captive lifespans were longer; and in captivity, females in particular had a reduced risk of dying prematurely.…”

“…Fernandez-Duque's [this issue] contribution examines a rich long-term data set on wild owl monkeys ( Aotus azarae ), which are largely agreed to be monogamous based on both social and genetic criteria [Fuentes 1998, Huck et al 2014]. This contribution examines the hypothesis that the spatial and temporal distribution of resources (and females) are predictors of social monogamy in Aotus .…”