Showing papers by "Anthony Di Fiore published in 2009"

Drought sensitivity of the Amazon rainforest.

Abstract: Amazon forests are a key but poorly understood component of the global carbon cycle. If, as anticipated, they dry this century, they might accelerate climate change through carbon losses and changed surface energy balances. We used records from multiple long-term monitoring plots across Amazonia to assess forest responses to the intense 2005 drought, a possible analog of future events. Affected forest lost biomass, reversing a large long-term carbon sink, with the greatest impacts observed where the dry season was unusually intense. Relative to pre-2005 conditions, forest subjected to a 100-millimeter increase in water deficit lost 5.3 megagrams of aboveground biomass of carbon per hectare. The drought had a total biomass carbon impact of 1.2 to 1.6 petagrams (1.2 × 1015 to 1.6 × 1015 grams). Amazon forests therefore appear vulnerable to increasing moisture stress, with the potential for large carbon losses to exert feedback on climate change.

Dispersal patterns in sympatric woolly and spider monkeys: integrating molecular and observational data

Abstract: Dispersal is a behavioral process that shuffles genes across the physical and social landscapes. Analysis of how genetic variation is structured hierarchically and among males versus females can provide insights into underlying dispersal processes, even when direct observations of dispersal events are lacking, but application of these techniques in primate studies has been limited. We investigated dispersal patterns in two South American primates — woolly and spider monkeys — using a combination of multilocus genotype data from > 150 animals sampled at two sites in Amazonian Ecuador and opportunistic field observations that shed light on likely dispersal events. Molecular analyses revealed considerable gene flow by females, but substantial male-mediated gene flow was also detected, particularly for woolly monkeys. In both taxa, the extent of population differentiation between the two study sites was greater for males than for females, indicating that gene flow by males has been more restricted historically. Additionally, in one group of spider monkeys, the average relatedness among adult males was significantly greater than that among females, consistent with strong male philopatry, and assignment tests for that group likewise suggest female-biased dispersal. However, for another group of spider monkeys — and for all groups of woolly monkey surveyed — these patterns were not observed. Our molecular results are concordant with field observations of immigrations by female spider monkeys, disappearances (likely emigrations) involving females of both species, and multiple sightings of solitary males and small bachelor groups in woolly monkeys, as well as with the specific dispersal histories of a few woolly monkey individuals discernable through longitudinal molecular sampling. Overall, the results demonstrate the utility of molecular approaches to studying dispersal in primates as a complement to observational studies, but also suggest that further evaluation of dispersal patterns among these primates is needed.

Paternity alone does not predict long-term investment in juveniles by male baboons.

Abstract: Adult male chacma baboons (Papio hamadryas ursinus) form preferential associations, or friendships, with particular lactating females. Males exhibit high levels of affiliative contact with their friends’ infants and defend them from potentially infanticidal attacks (Palombit et al. 1997). Little is known about males’ associations with juveniles once they have passed the period of infanticidal risk. We conducted an observational, experimental, and genetic study of adult male and juvenile chacma baboons in the Moremi Reserve, Botswana. We identified preferential associations between males and juveniles and used behavioral data and a playback experiment to explore whether those associations have potential fitness benefits for juveniles. We determined whether males preferentially invest in care of their own offspring. We also determined how often males invest in care of their former friends’ offspring. The majority of juveniles exhibited preferential associations with one or two males, who had almost always been their mother’s friend during infancy. However, in only a subset of these relationships was the male the actual father, in part because many fathers died or disappeared before their offspring were weaned. Male caretakers intervened on behalf of their juvenile associates in social conflicts more often than they intervened on behalf of unconnected juveniles, and they did not appear to differentiate between genetic offspring and unrelated associates. Playbacks of juveniles’ distress calls elicited a stronger response from their caretakers than from control males. Chacma males may provide care to unrelated offspring of former friends because the costs associated with such care are low compared with the potentially high fitness costs of refusing aid to a juvenile who is a possible offspring.

Genetic Approaches to the Study of Dispersal and Kinship in New World Primates

Abstract: Among social animals such as primates, “kinship” or genetic relatedness is commonly invoked as a key factor underlying and organizing the expression of within-group social behavior (Alexander 1974; Wilson 1975; Gouzoules 1984; Bernstein 1991; Silk 2001, 2002). Indeed, kin-correlated behavior – particularly kin-directed beneficent behavior or “nepotism” – is often considered a hallmark feature of the social lives of group-living primates (Gouzoules 1984; Gouzoules and Gouzoules 1987). Within primate social groups, the patterns of genetic relatedness among group members are influenced principally by the dispersal and mating behaviors of those individuals. Dispersal directly shuffles genes across the physical and social landscapes, reassorting how the genetic variation present in a population is partitioned geographically and both within and among the various demographic units (e.g., social groups) into which the population is divided. Individuals’ social and reproductive behaviors (e.g., mating frequency, choice of partners) likewise can influence the structuring of genetic variation within and among social groups across time. For example, high reproductive skew among males within a social group can lead to cohorts of similarly aged individuals being more closely related to one other through common paternity than are animals of different ages. Similarly, extra-group mating by either males or females can act to reduce the extent of genetic differentiation between groups. These two key behavioral factors influencing the kinship structure of primate groups – the dispersal and reproductive tactics of individual animals – are some of the most intractable features of primate social systems for researchers to study in the field. For long-lived species such as primates, dispersal events tend to be rare – i.e., individual animals typically disperse only once or a small number of times during their lives. Even in the most detailed, long-term field studies, it is often difficult