Climate as a driver of tropical insular diversity: comparative phylogeography of two ecologically distinctive frogs in Puerto Rico.
The effects of late Quaternary climate on distributions and evolutionary dynamics of insular species are poorly understood in most tropical archipelagoes. We used ecological niche models under past and current climate to derive hypotheses regarding how stable climatic conditions shaped genetic diversity in two ecologically distinctive frogs in Puerto Rico. Whereas the Mountain Coquí,Eleutherodactylus portoricensis, is restricted to montane forest in the Cayey and Luquillo Mountains, the Red-eyed Coquí,E. antillensis, is a habitat generalist distributed across the entire Puerto Rican Bank (Puerto Rico and the Virgin Islands, excluding St. Croix). To test our hypotheses, we conducted phylogeographic and population genetic analyses based on mitochondrial and nuclear loci of each species across their range in Puerto Rico. Patterns of population differentiation inE. portoricensis, but not inE. antillensis, supported our hypotheses. ForE. portoricensis, these patterns include: individuals isolated by long-term unsuitable climate in the Río Grande de Loíza Basin in eastern Puerto Rico belong to different genetic clusters; past and current climate strongly predicted genetic differentiation; and Cayey and Luquillo Mountains populations split prior to the last interglacial. ForE. antillensis, these patterns include: genetic clusters did not fully correspond to predicted long-term unsuitable climate; and past and current climate weakly predicted patterns of genetic differentiation. Genetic signatures inE. antillensisare consistent with a recent range expansion into western Puerto Rico, possibly resulting from climate change and anthropogenic influences. As predicted, regions with a large area of long-term suitable climate were associated with higher genetic diversity in both species, suggesting larger and more stable populations. Finally, we discussed the implications of our findings for developing evidence-based management decisions forE. portoricensis, a taxon of special concern. Our findings illustrate the role of persistent suitable climatic conditions in promoting the persistence and diversification of tropical island organisms.
Department of Biology, University of New Mexico, Albuquerque, New Mexico 87131-0001, USA ; Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona 85721, USA.
Brittany S
BS
Barker
School of Life Sciences, University of Nevada, Las Vegas, 4505 Maryland Parkway, Las Vegas, NV 89154-4004, USA.
Javier A
JA
Rodríguez-Robles
Department of Biology, University of New Mexico, Albuquerque, New Mexico 87131-0001, USA ; Museum of Southwestern Biology, University of New Mexico, Albuquerque, New Mexico 87131-0001, USA.
Joseph A
JA
Cook