Understanding the mechanisms that underlie evolutionary diversification in tropical forests has intrigued scientists for more than a century. The Pleistocene refugia hypothesis proposes that forest fragmentation during glacial maxima led to the isolation and subsequent diversification of associated taxa, and this hypothesis is often suggested as a possible explanation for patterns of speciation among Neotropical primates. Spider monkeys are distributed from Panama to the Yucatan peninsula of Mexico and are among the most diverse primate genus in Mesoamerica. It has been suggested that they first entered Mesoamerica roughly two million years ago, shortly after the formation of the Isthmus of Panama. Currently, at least two species and nine subspecies are recognized, based mainly on regional differences in pelage color. However, the phylogenetic relationships among these various forms of Mesoamerican spider monkeys are still debated and the significance of the extensive morphological variation seen within the genus is poorly understood. Some authors have questioned the use of pelage color as a valid trait for separating species and subspecies, and others have stressed the importance of evaluating the genetic diversity that underlies variation in coat color. This project will contribute to a better understanding of the evolutionary history of Mesoamerican spider monkeys by [1] documenting the genetic relationships within and among currently recognized spider monkey forms and [2] examining whether the current diversity of spider monkeys in Mesoamerica can be explained by the Pleistocene refugia hypothesis. The project will yield the most comprehensive molecular assessment of Mesomerican spider monkey phylogenetic relationships and biogeography undertaken to date and may help elucidate likely causes of diversification and speciation among Mesoamerican fauna more generally. From a conservation perspective, it will contribute to understanding of which forms of spider monkeys represent distinct evolutionary lineages, which is crucial for developing effective conservation and management programs.
