Puberty and dispersal in a wild primate population

Abstract

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.

Developmental variations in environmental influences including endocrine disruptors on pubertal timing and neuroendocrine control: Revision of human observations and mechanistic insight from rodents

“…2 are shown the species-related differences in relative duration of the prepubertal latency (from birth to puberty) when calculated as a percentage of lifespan for comparison purposes. Ewe (Foster et al, 1985), rat (Maeda et al, 2000) and quail (Ottinger et al, 2003) start puberty after a latency accounting for 4.8-5.7% of the lifespan as opposed to 16.3% in humans (Roelants et al, 2009) and 22.5% in baboons (Onyango et al, 2013) that is about 3-4 times longer than in non-primate species. Another less emphasized species-related difference is the variance of pubertal timing among individuals.…”

“…2). The baboon, a subhuman primate shows a variance of pubertal timing (Onyango et al, 2013) that is even longer than in humans, when expressed relatively to average lifespan (10.0%). These data indicate that inter-individual variations in pubertal timing may be influenced by evolution across species.…”

The baboon (Papio sp.) as a model for female reproduction studies

“…Typically, the infants are carried by the dams until approximately 5 to 6 months of age when the dam will wean the infant off the breast [6, 19, 30.] The infant will still cling to the dam (even if pregnant again), or other adults after weaning, learning the normal foraging and other behaviors of the adults [7. ]…”

“…Sexually mature female baboons typically range in weight from 14 – 18 kg, but can approach 30kg if obese [5.] Baboons have a relatively long life span and sexual maturity occurs at age 4–6 [6, 7, 8.] Females naturally experience an interbirth interval of approximately one to three years [6, 9,] which allows for multiple birthing event studies to be conducted in a reasonable timeline in this closely related species.…”

Dispersal Evolution in the Presence of Allee Effects Can Speed Up or Slow Down Invasions

“…This forces a model to ignore sex-specific differences not only in life-history traits, such as body size, survival, and age of maturation (Bradley et al 1980;Fairbairn 1997;Onyango et al 2013), but also in movement behaviors, such as tendency to leave the natal area and total distance traveled (Greenwood 1980;Waser and Jones 1983;Clarke et al 1997;Miller et al 2011). An added complication of sexually reproducing species is the requirement that individuals find mate(s) before reproducing, which can be increasingly difficult at low densities (Dennis 1989;Wells et al 1998;Courchamp et al 2008).…”