9419765 Losos In recent years , our ability to discover the phylogenetic relationships among species (i.e., how species are related to one another) has increased substantially, thanks to advances both in our ability to collect relevant data, such as DNA sequences, and in analytical advances in the ability to utiliza this information to deduce phylogenies. Although the relationships among species are interesting and scientifically important in their own right, phylogenies can be useful for other purposes as well. %%% This symposium will demonstrate the utility of phylogenies for framing hypothese that can be tested. In the past, phylogenies have been used to examine previously-derived hypotheses; i.e. hypotheses were framed based on other data and then examined in the context of the phylogeny to determine whether species had changed as predicted. However, this sympoqium will illustrate how phylogenies can be used to actually derive hypotheses that can then be tested by gathering data on extant taxa. For example, based on a phylogeny, one might deduce that a given feature had evolved earlier than the occupation of the new habitat. Thus, one might propose that the feature was required for use of that habitat, which one could then test experimentally using extant organisms. This symposium will include workers in fields as disparate as developemntal biology, behavior, ecology and conservation to illustrate the powerful uses to which phylogenies can be put to generate testable hypotheses. ***
