9706183 Golenberg During the Quaternary, the Earth underwent the last major environmental changes, which were manifested by dramatic swings in atmospheric chemistry and climate. These environmental changes coincide with massive shifts in species and community distributions, which inevitably are associated with population fragmentation, ecotype evolution and formation of sibling species. Yet the morphological evidence of patterns of Quaternary evolution remains sparse. Genetic analyses which could document the patterns of evolution have been negligible despite the wealth of well preserved plant and animal tissue in packrat middens. These dry depositions are ideal for the preservation of DNA, allowing one to estimate species ranges, ecotonal boundaries, hybrid zones; and migrational histories with high spatio-temporal resolution. The delayed progress in DNA analyses of this material is the reluctance to support problem driven research utilizing ancient DNA analysis when the reliability, repeatability, and taxonomic and chronological range of DNA preservation is not well established. To determine the contributions of taxonomic breadth, length of time, and geographical/environmental restrictions to long term DNA preservation, material from five plant taxa (Pinus spp., Juniperus spp., Artemisia spp., Atriplex spp., and Yucca spp.) will be sampled over increasing age increments from fresh and recently preserved to material retrieved from woodrat middens from 90 up to +38,000 years old. To complete this aim, our objectives are: ( To extract DNA from dated vegetative material (leaf, needle, scales, and stems) from a wide geographically and chronological range, ( To amplify, sequence, and analyze gene sequences from the chloroplast regions rbcL, trnL to trnF intergenic region, and the nuclear ITS regions of the ribosomal repeats, ( To assess rates of successful retrieval as functions of taxon, age, age and tissue type. Prior results from independent laboratories have demonstrate d that DNA can be extracted from packrat midden material. Our own preliminary results show that DNA regions that are diagnostic to the subspecies level can be retrieved. The ultimate long range goal of our research is to exploit the large amounts of subfossil material to combine, morphological, physiological, biogeographical studies with the underlying genetic dynamics of the populations as they evolved and migrated during the Quaternary. This goal will be the first merger of population genetic and paleontological studies, and may serve as tests to our understanding of the relevance of microevolution to macroevolution. Additionally, in terms of practical implications of the long term goals, defining the evolutionary processes behind these historical occurrences is manifestly relevant towards understanding and predicting modern biospheric responses to natural and anthropogenic climatological changes.
