The demography of a resource specialist in the tropics: Cecropia trees and the fitness of three-toed sloths

Resource specialists persist on a narrow range of resources. Consequently, the abundance of key resources should drive vital rates, individual fitness and population viability. While Neotropical forests feature both high levels of biodiversity and numbers of specialist species, no studies have directly evaluated how the variation of key resources affects the fitness of a tropical specialist. Here, we quantified the effect of key tree species density and forest cover on the fitness of three-toed sloths (Bradypus variegatus), an arboreal folivore strongly associated with Cecropia trees, in Costa Rica using a multi-year demographic, genetic and space use dataset. We found that the density of Cecropia trees was strongly and positively related to both adult survival and reproductive output. A matrix model parameterized with Cecropia-demography relationships suggested positive growth of sloth populations, even at low densities of Cecropia (0.7 trees/ha). Our study shows the first direct link ...