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Roads affect wildlife in a variety of negative ways. Road ecology studies have mostly concentrated on areas in the northern hemisphere despite the potentially greater impact of roads on biodiversity in tropical habitats. Here, we examine 4 years (January 2016–December 2019) of opportunistic observations of mammalian roadkill along a road intersecting Jozani-Chwaka Bay National Park, Unguja, Zanzibar. In particular, we assess the impact of collisions on the population of an endemic primate, the Endangered Zanzibar red colobus Piliocolobus kirkii. Primates accounted for the majority of roadkill in this dataset. Monthly rainfall was not associated with roadkill frequency for mammals generally, nor for the Zanzibar red colobus. No single age–sex class of colobus was found dead more often than expected given their occurrence in the local population. The overall effect of roadkill on colobus populations in habitats fragmented by roads is unknown given the lack of accurate, long-term life history data for this species. Our findings suggest that mortality from collisions with vehicles in some groups of colobus is within the range of mortality rates other primates experience under natural predation. Unlike natural predators, however, vehicles do not kill selectively, so their impact on populations may differ. Although a comparison with historical accounts suggests that the installation of speedbumps along the road near the Park's entrance has led to a significant decrease in colobus roadkill, further actions to mitigate the impact of the road could bring substantial conservation benefits. [ABSTRACT FROM AUTHOR]

By tracking a group of individuals through time, cohort studies provide fundamental insights into the developmental time course and causes of health and disease. Evolutionary life history theory seeks to explain patterns of growth, development, reproduction and senescence, and inspires a range of hypotheses that are testable using the longitudinal data from cohort studies. Here we review two decades of life history theory-motivated work conducted in collaboration with the Cebu Longitudinal Health and Nutrition Survey (CLHNS), a birth cohort study that enrolled more than 3000 pregnant women in the Philippines in 1983 and has since followed these women, their offspring and grandoffspring. This work has provided evidence that reproduction carries "costs" to cellular maintenance functions, potentially speeding senescence, and revealed an unusual form of genetic plasticity in which the length of telomeres inherited across generations is influenced by reproductive timing in paternal ancestors. Men in Cebu experience hormonal and behavioural changes in conjunction with changes in relationship and fatherhood status that are consistent with predictions based upon other species that practice bi-parental care. The theoretical expectation that early life cues of mortality or environmental unpredictability will motivate a "fast" life history strategy are confirmed for behavioural components of reproductive decision making, but not for maturational tempo, while our work points to a broader capacity for early life developmental calibration of systems like immunity, reproductive biology and metabolism. Our CLHNS findings illustrate the power of life history theory as an integrative, lifecourse framework to guide longitudinal studies of human populations. [ABSTRACT FROM AUTHOR]

Understanding the determinants of pubertal timing, particularly menarche in girls, is an important area of investigation owing to the many health, psychosocial, and demographic outcomes related to reproductive maturation. Traditional explanations emphasized the role of favorable nutrition in maturational acceleration. More recently, work has documented early maturity in relation to markers of familial and environmental instability (e.g. paternal absence), which are hypothesized to serve as cues triggering adaptive adjustment of life history scheduling. While these studies hint at an ability of human females to accelerate maturity in stressful environments, most have focused on populations characterized by energetic excess. The present study investigates the role of developmental nutrition alongside cues of environmental risk and instability (maternal absence, paternal absence, and sibling death) as predictors of menarcheal age in a well-characterized birth cohort born in 1983 in metropolitan Cebu, the Philippines. In this sample, which was marked by a near-absence of childhood overweight and obesity, we find that menarcheal age is not predicted by cues of risk and instability measured at birth and during childhood and early adolescence, but that infancy weight gain and measures of favorable childhood nutrition are strong predictors of maturational acceleration. These findings contrast with studies of populations in which psychosocial stress and instability co-occur with excess weight. The present findings suggest that infancy and childhood nutrition may exert greater influence on age at menarche than psychosocial cues in environments characterized by marginal nutrition, and that puberty is often delayed, rather than accelerated, in the context of stressful environments. [ABSTRACT FROM AUTHOR]