9311004 Shaffer Explanations for species differences in color patterns have usually invoked variation in perceptual systems, such as female preferences. Because conspicuousness of color depends upon context, properties of the environment should also affect the evolution of color patterns. Through observational and experimental studies, Ms. Karen Marchetti has shown that differences in color patterns among warbler species of the genus Phylloscopus can be predicted from environmental and behavioral features that affect signal transmission. Her studies were conducted at one locality in the breeding season, and concentrated on mechanisms of sexual selection (female choice and male-male competition). Now she will extend the study to encompass the non-breeding season and geographical variation. First, she will experimentally manipulate plumage patterns of one species, which maintains individual territories through the winter, in order to examine potential selective forces (such as predation) that could balance identified selective forces in the breeding season. Second, she will study a new locality in the breeding season, measuring the extent to which geographical variation in coloration (within species) is associated with geographic variation in habitat. Third, she will examine habitat associations and display movements in other groups of birds to determine the extent to which factors influencing the evolution of coloration in Phylloscopus can be generalized. This doctoral-dissertation research will contribute to a number of important areas in evolutionary and behavioral biology. It will shed light on the conditions that lead to sameness or difference in appearance between males and females, on the mechanisms of sexual selection, and on the importance of the non-breeding season in affecting the evolution of displays and plumage patterns.
