This project includes an intensive field collecting phase and a follow-up laboratory analysis phase, in that order. The field research centers on making research collections almost entirely in Mexico, under the direction of a Mexican scientist and his students, of the conspicuous and extremely diverse lizard genus Sceloporus. Of the specimens collected, at least 60% will be deposited as standard museum vouchers in a research collection at Mexico's National University, and the remaining specimens (the final proportions will be determined by permit requirements) will likewise be catalogued in U.S. collections. Simultaneously, large collection of frozen tissue samples will be made from these animals upon their capture, and all frozen tissues will be returned and catalogued into U.S. tissue collections. Species and distinct populations will be collected nonrandomly so as to maximize the utility of the samples for addressing a variety of basic questions in ecology and historical biogeography. For example, selected species are to be collected from the Baja Peninsula, some islands in the Sea of Cortez, and the western mainland of Mexico for the purpose of testing alternative ideas concerning the derivation of island populations relative to those of Baja and the mainland. These data will have important implications for understanding the origins of entire island biotas, since all species present on these islands were subjected to the same geological events which formed the Baja Peninsula and the Sea of Cortez, and for emphasizing the value of these still largely intact systems for conservation. A second group of lizards will be collected from the transverse volcanic range of central Mexico because these populations display different stages of the transition from egg-laying to live- bearing reproductive modes associated with adaptions to high elevations. In both cases, laboratory work will utilize two independent classes of molecular markers, including proteins and DNA molecules, to reconstruct the genealogies of the populations sampled. The lab work will support extensive training opportunities and collaboration for both Mexican and U.S. graduate students and research associates.
