This award will support Professor Lawrence Gilbert of the University of Texas at Austin in a research collaboration with Professor Mauricio Linares of the Fundacion Segunda Expedicion Botanica in Bogota, Colombia. The researchers intend to study the evolutionary consequences of human impact on tropical forests. In a previous study it was shown that the frequency of polymorphic forms in a particular butterfly population changed dramatically during the past century. It was hypothesized that these changes were caused by human perturbation. In the proposed work, the investigators will gather additional evidence about the nature of the recent evolutionary changes in the same system, and the selection pressures that have been responsible for these changes. The results will generate hypotheses about the nature of current natural selection on morph frequency. Such secondary hypotheses will be tested by comparing the distributions of phenotypes in the wild with their distributions among the offspring of wild- caught butterflies from disturbed and undisturbed habitats.