Repetitive DNA Sequences in Genome Organization of Phyllostomoid Bats: Test of a Molecular Model for Chromosomal Divergence

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The design of this proposal brings strengths from molecular biology, cytogenetics, and cladistics to test the hypothesis that rapid chromosomal change and karyotypic stasis are primarily mediated at the molecular level by activity of repetitive sequences. We predict that taxa with radically reorganized karyotypes will have: 1) an abundance of copies and classes of rapidly evolving repetitive sequences;2) tandemly repeated sequences will have actively changed chromosomal fields among nonhomologous chromosomes; and 3) interspersed repeated sequences will have undergone changes in sequence and copy number due to transposition. Alternatively, lineages experiencing long periods of karyotypic stasis will have: 1) fewer classes of tandemly repeated sequences is low copy number; 2) tandemly repeated sequences restricted to specific chromosomal regions; and 3) interspersed elements will evolve at a rate similar to that of other neutral DNA, due to a lower rate of transposition. New World leaf-nosed bats were chosen because monophyly of taxa to be studied is well documented and they exhibit extremes in rates and types of karyotypic evolution. Methods of examination will include phylogenetic screening of genome libraries to determine the number and kind of rapidly evolving repetitive sequences. Chromosomal position and movement will be documented by cladistical analysis of data from in situ hybridization.