This U.S.-Mexico award will support a research collaboration between Dr. Linden E. Higgins of the University of Massachusetts and Dr. Juan Nunez Farfan of the Instituto de Ecologia of the Universidad Nacional Autonoma de Mexico (UNAM) in Mexico City. The researchers intend to study the mechanisms of evolution of local adaptation in organisms found in diverse habitats. Not all species found in diverse habitats show local adaptation, and an improved understanding of why species fail to evolve local specialization will improve our understanding of how and when evolutionary diversification can proceed. A central question of their project is: Why do some species remain coherent units over diverse habitats?
The large, orb-weaving spider Nephila clavipes (Araneae: Tetraglathidae) is found throughout central and southern Mexico, continuously distributed along a cline from the Gulf Coast to the Pacific coast and in isolated peripheral populations in mid-altitude mountainous locations. There is little local differentiation among these populations, and the species exhibits great phenotypic plasticity in many aspects of its biology. Two alternative models will provide the researchers with testable predictions concerning the amount of genetic differentiation and local adaptation among populations. Predictions arising from these two alternative models of species coherence will be tested using field observations, molecular genetics, and laboratory experiments. The collaboration will benefit from bringing together the U.S. PI's expertise on the ecology, development, behavior, and physiology of the chosen spider species, with the Mexican PI's work on the phenotypic evolution in different organisms using the framework of quantitative and population genetics.
