67 research outputs found
Multi-Scale Predictors of Parasite Risk in Wild Male Savanna Baboons (Papio Cynocephalus)
Several factors are thought to shape male parasite risk in polygynous and polygynandrous mammals, including male-male competition, investment in potentially immunosuppressive hormones, and dispersal. Parasitism is also driven by processes occurring at larger scales, including host social groups and populations. To date, studies that test parasite-related costs of male behavior at all three scales—individual hosts, social groups, and the host population—remain rare. To fill this gap, we investigated multi-scale predictors of helminth parasitism in 97 male savanna baboons (Papio cynocephalus) living in the Amboseli ecosystem in Kenya over a 5-year span. Controlling for multi-scale processes, we found that many of the classic indicators of male mating effort—high dominance rank, testosterone, and glucocorticoids—did not predict helminth infection risk. However, we identified two parasite-related costs associated with male behavior: (i) socially connected males exhibited higher Trichuris trichiura egg counts and greater parasite species richness than socially isolated males and (ii) males with stable group residency exhibited higher parasite species richness than males who frequently dispersed to new social groups. At the population level, males harbored more parasites following periods of drought than rainfall. Lastly, parasites exhibited positive covariance suggesting that infection risk increases if a host already harbors one or more parasite taxa. These results indicate that multi-scale processes are important in driving male parasite risk and that some aspects of male behavior are costly. Together, our results provide an unusually holistic perspective on the drivers of parasite risk in the context of male behaviors and life histories
Data from: Costs and benefits of group living in primates: an energetic perspective
Group size is a fundamental component of sociality, and has important consequences for an individual's fitness as well as the collective and cooperative behaviours of the group as a whole. This review focuses on how the costs and benefits of group living vary in female primates as a function of group size, with a particular emphasis on how competition within and between groups affects an individual's energetic balance. Because the repercussions of chronic energetic stress can lower an animal's fitness, identifying the predictors of energetic stress has important implications for understanding variation in survivorship and reproductive success within and between populations. Notably, we extend previous literature on this topic by discussing three physiological measures of energetic balance—glucocorticoids, c-peptides and thyroid hormones. Because these hormones can provide clear signals of metabolic states and processes, they present an important complement to field studies of spatial and temporal changes in food availability. We anticipate that their further application will play a crucial role in elucidating the adaptive significance of group size in different social and ecological contexts
Raw for Analyses
Total number of individuals, biomass (kg), and energetic demand (kg3/4) for 14 baboon social groups from 1990-2014 hydrological years (Nov-Oct). Analyses included only group-hydrological years in which the focal group was censused every calendar month during the hydrological year. Data provided by ABRP
Raw for Figure 2
Percent contribution by age-sex class to group’s total number of individuals, biomass (kg), and energetic demand (kg3/4) for 14 baboon social groups from 1990-2014 hydrological years (Nov-Oct). Analyses included only group-hydrological years in which the focal group was censused every calendar month during the hydrological year. Data provided by ABRP
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Testosterone positively associated with both male mating effort and paternal behavior in savanna baboons (Papio cynocephalus)
Testosterone (T) is often positively associated with male sexual behavior and negatively
associated with paternal care. These associations have primarily been demonstrated in species
where investment in paternal care begins well after mating activity is complete, when offspring are
hatched or born. Different patterns may emerge in studies of species where investment in mating
and paternal care overlap temporally, for instance in non-seasonal breeders in which males mate
with multiple females sequentially and may simultaneously have multiple offspring of different
ages. In a 9-year data set on levels of T in male baboons, fecal concentrations of T (fT) were
positively associated with both mate guarding (“consortship”) – a measure of current reproductive
activity – and with the number of immature offspring a male had in his social group – a measure
of past reproductive activity and an indicator of likely paternal behavior. To further examine the
relationship between T and potential paternal behavior, we next drew on an intensive 8-month
study of male behavior, and found that fathers were more likely to be in close proximity to their
offspring than expected by chance. Because male baboons are known to provide paternal care, and
because time in proximity to offspring would facilitate such care, this suggests that T
concentrations in wild male baboons may be associated with both current reproductive activity and
with current paternal behavior. These results are consistent with the predicted positive association
between T a mating effort but not nd with a negative association between T a paternal care; in
male baboons, high levels of nd T occur in males that are differentially associating with their
offspring
Data from: Interbirth intervals in wild baboons: environmental predictors and hormonal correlates
Objectives: Interbirth intervals (IBIs) are a key metric of female reproductive success; understanding how they are regulated by environmental, social, and demographic factors can provide insight into sources of variance in female fitness. Materials and Methods: Using 36 years of reproductive data on 490 IBIs for 160 wild female baboons, we identified sources of variance in the duration of IBIs and of their component phases: postpartum amenorrhea (PPA), sexual cycling, and pregnancy. We also examined how body fat and fecal hormone concentrations varied during female IBI.
Results: We found that IBIs tended to be shorter (reproduction was accelerated) when female traits and environmental variables promoted energy acquisition, but with different specific effects for different component phases of the IBI. We also found that females lost a substantial amount of body fat during PPA, indicating that PPA imposes accumulating energetic costs as it progresses. Prior to cycle resumption females began to regain body fat; body fat was stable across the cycling phase and increased throughout most of pregnancy. However, body fat scores per se were not associated with the duration of any of the component phases. Finally, we found that fecal glucocorticoid concentrations decreased as PPA progressed, suggesting a decline in energetic stress over this phase. Fecal progestogen and estrogen concentrations changed over time during sexual cycling; the direction of these changes depended on the phase of the sexual cycle (luteal versus early or late follicular phases). Discussion: Our study lends insight into the energetic constraints on female primate reproduction, revealing how female environments, changes in body fat, and steroid hormone concentrations relate to IBI duration and to reproductive readiness
mT3 concentrations for wild baboons
This dataset was used to assess whether seasonal variation in rainfall and female reproductive status affected mT3 concentrations in wild baboons. For this analysis we used 377 fecal samples from 61 wild adult females. These samples were the leftover freeze-dried fecal powder from samples collected between January 2008 and October 2015 for steroid hormone analyses. The freeze-dried fecal powder had been stored at -20 °C for period of time ranging from 1.3 years (for the samples collected in October 2015) to 9.1 years (for the samples collected in January 2008)
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Puberty and dispersal in a wild primate population
The onset of reproduction is preceded by a host of organismal adjustments and transformations,
involving morphological, physiological, and behavioral changes. In highly social mammals,
including humans and most nonhuman primates, the timing and nature of maturational processes
is affected by the animal’s social milieu as well as its ecology. Here, we review a diverse set of
findings on how maturation unfolds in wild baboons in the Amboseli basin of southern Kenya, and
we place these findings in the context of other reports of maturational processes in primates and
other mammals. First, we describe the series of events and processes that signal maturation in
female and male baboons. Sex differences in age at both sexual maturity and first reproduction
documented for this species are consistent with expectations of life history theory; males mature
later than females and exhibit an adolescent growth spurt that is absent or minimal in females.
Second, we summarize what we know about sources of variance in the timing of maturational
processes including natal dispersal. In Amboseli, individuals in a food-enhanced group mature
earlier than their wild-feeding counterparts, and offspring of high-ranking females mature earlier
than offspring of low-ranking females. We also report on how genetic admixture, which occurs in
Amboseli between two closely related baboon taxa, affects individual maturation schedules
Linking social environment and stress physiology in feral mares (Equus caballus): Group transfers elevate fecal cortisol levels
Feral horses (Equus caballus) have a complex social structure, the stability of which is important to their overall health. Behavioral and demographic research has shown that decreases in group (or band) stability reduce female fitness, but the potential effects on the physiological stress response have not been demonstrated. To fully understand how band stability affects group-member fitness, we need to understand not only behavioral and demographic, but also physiological consequences of decreases to that stability. We studied group changes in feral mares (an activity that induces instability, including both male and female aggression) on Shackleford Banks, NC. We found that mares in the midst of changing groups exhibit increased fecal cortisol levels. In addition, mares making more group transfers show higher levels of cortisol two weeks post-behavior. These results offer insights into how social instability is integrated into an animal\u27s physiological phenotype. In addition, our results have important implications for feral horse management. On Shackleford Banks, mares contracepted with porcine zona pellucida (PZP) make approximately 10 times as many group changes as do untreated mares. Such animals may therefore be at higher risk of chronic stress. These results support the growing consensus that links between behavior and physiological stress must be taken into account when managing for healthy, functional populations. © 2013 Elsevier Inc
Data from: Optimal group size in a highly social mammal
What are the costs and benefits for animals living in groups of different sizes? Balancing the trade-offs between within-group competition (which favors smaller groups) and between-group competition (which favors larger groups) suggests that intermediate-sized groups may be best, yet empirical support for this prediction has largely been lacking. Using long-term data on wild baboons, we provide novel evidence that individuals living in intermediate-sized groups have energetically optimal space-use strategies and lower glucocorticoid (stress hormone) concentrations than individuals in either large or small groups. Our results offer new insight into the costs and benefits of group living
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