Natural selection, the differential survival and reproduction of individuals possessing different traits, is a major process driving evolutionary change. One sign of natural selection is convergent evolution: when traits in different species that occupy the same environment evolve in a similar matter. Although convergence was once assumed to be rare, recent research demonstrates that convergence occurs quite commonly. An outstanding question, however, is whether closely related species and populations are more likely to converge, both in their physical characteristics and in their genes, than more distant relatives. Similarities in natural history and genetic makeup might predispose close relatives to adapt in similar ways to similar circumstances. Moreover, contemporary adaptation to the changed environmental circumstances resulting from human actions is increasingly common. It is not known whether species are adapting to anthropogenically induced selective pressures in the same way as they have adapted to natural changes in the environment. This is an important question because species' survival in the face of environmental change may depend on evolving adaptations to new conditions. Conservationist scientists are gaining interest in how to make evolutionary adaptation more likely. The predictions about adaptation that will result from this research may be useful in guiding actions to maximize that evolutionary potential of populations. Students will be trained in international scientific research, and several outreach activities will engage the general public in better understanding of scientific issues.
This study will address these questions by focusing on two groups of lizard, Caribbean Anolis lizards and South African chameleons, and examining the degree to which convergence occurs at multiple levels: between lizard groups separated by millions of years of evolutionary divergence, within each of these clades, and among modern-day populations adapting to human-altered environments. These questions will be investigated both by examining anatomical characteristics, for example leg length and body size, and by studying genetic differences among diverse groups of lizards. In addition, comparisons across populations and species will help identify candidate genes that may be responsible for the observed anatomical differences. New gene editing methods will be used to directly test whether these genetic changes actually produce the predicted anatomical changes. These studies will play an important role in understanding the limits of natural selection in shaping adaptation to future environmental change.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
