Browsing by Author "Nuñez, Chase L"
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Item Open Access Low-intensity logging and hunting have long-term effects on seed dispersal but not fecundity in Afrotropical forests.(AoB PLANTS, 2019-02) Nuñez, Chase L; Clark, James S; Clark, Connie J; Poulsen, John RHunting and logging, ubiquitous human disturbances in tropical forests, have the potential to alter the ecological processes that govern population recruitment and community composition. Hunting-induced declines in populations of seed-dispersing animals are expected to reduce dispersal of the tree species that rely on them, resulting in potentially greater distance- and density-dependent mortality. At the same time, selective logging may alter competitive interactions among tree species, releasing remaining trees from light, nutrient or space limitations. Taken together, these disturbances may alter the community composition of tropical forests, with implications for carbon storage, biodiversity conservation and ecosystem function. To evaluate the effects of hunting and logging on tree fecundity and seed dispersal, we use 3 years of seed rain data from a large-scale observational experiment in previously logged, hunted and protected forests in northern Republic of Congo (Brazzaville). We find that low-intensity logging had a meaningful long-term effect on species-specific seed dispersal distances, though the direction and magnitude varied and was not congruent within dispersal vector. Tree fecundity increased with tree diameter, but did not differ appreciably across disturbance regimes. The species-specific dispersal responses to logging in this study point towards the long-lasting toll of disturbance on ecological function and highlight the necessity of conserving intact forest.Item Open Access Offspring of primiparous mothers do not experience greater mortality or poorer growth: Revisiting the conventional wisdom with archival records of Rhesus Macaques.(Am J Primatol, 2015-06-01) Nuñez, Chase L; Grote, Mark N; Wechsler, Michelle; Allen-Blevins, Cary R; Hinde, KatieFemale mammals often begin to reproduce before achieving somatic maturity and therefore face tradeoffs between allocating energy to reproduction or their own continued development. Constraints on primiparous females are associated with greater reproductive failure, and first-born infants often have slower growth and greater mortality and morbidity than infants born to multiparous females. Effects of early life investment may persist even after weaning when juveniles are no longer dependent on maternal care and mother's milk. We investigated the long-term consequences of birth order in a large sample of rhesus macaques, Macaca mulatta, assigned to the outdoor breeding colony at the California National Primate Research Center (n = 2,724). A joint model for growth and mortality over the first three years of life allowed us to explicitly connect growth rates to survival. As expected, males are born heavier and grow faster relative to females. However, contrary to expectations, later-born males face substantially lower survival probability during their first three years, whereas first-born males survive at greater rates similar to both first-born and later-born females. Primiparous mothers are less likely to conceive during the subsequent breeding season, suggesting that their reproductive costs are greater than those of multiparous mothers. We speculate that compensatory tactics, both behavioral and physiological, of first-born offspring and their mothers, as well as the novel ecology of the captive environment, underlie these findings. The results presented here provide new insights into how maternal and infant life history tradeoffs may influence developmental trajectories even after the period of maternal dependence. Am. J. Primatol. © 2015 Wiley Periodicals, Inc.Item Open Access The ecological consequences of forest elephant declines for Afrotropical forests.(Conservation biology : the journal of the Society for Conservation Biology, 2017-10-27) Poulsen, John R; Rosin, Cooper; Meier, Amelia; Mills, Emily; Nuñez, Chase L; Koerner, Sally E; Blanchard, Emily; Callejas, Jennifer; Moore, Sarah; Sowers, MarkPoaching is rapidly extirpating African forest elephants (Loxodonta cyclotis) from most of their historical range, leaving vast areas of elephant-free tropical forest. Elephants are ecological engineers that create and maintain forest habitat, thus their loss will have strong consequences for the composition and structure of Afrotropical forests. We evaluated the roles of forest elephants in seed dispersal, nutrient recycling, and herbivory and physical damage to predict the cascading ecological effects of their population declines. Loss of seed dispersal by elephants will favor tree species dispersed abiotically and by smaller dispersal agents, with tree species composition depending on the downstream effects of changes in elephant nutrient cycling and browsing. Loss of trampling and herbivory of seedlings and saplings will result in high tree density as they are released from the pressures of browsing. Diminished seed dispersal by elephants and high stem density are likely to reduce the recruitment of large trees, resulting in a more homogeneous forest structure and decreased carbon stocks. In sum, the loss of ecological services by forest elephants will likely transform Central African forests to be more like Neotropical forests, from which megafauna were extirpated thousands of years ago. Without intervention, as much as 96% of Central African forests will have modified species composition and structure as elephants are compressed into remaining protected areas. Stopping elephant poaching is an urgent first step to mitigating these effects, but long-term conservation will require land use planning that incorporates elephant habitat into forested landscapes that are being rapidly transformed by industrial agriculture and logging. This article is protected by copyright. All rights reserved.