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

这一方案的设计结合了分子生物学、细胞遗传学和分支学的优势，以检验快速染色体变化和核型停滞主要由重复序列的活性在分子水平上调节的假设。我们预测，具有激进重组核型的分类群将具有：1)大量的副本和快速进化的重复序列；2)随机重复序列将在非同源染色体中主动改变染色体场；以及3)散布的重复序列将由于转座而在序列和拷贝数上发生变化。或者，经历长时间核型停滞的谱系将有：1)较少的重复序列类别是低拷贝数；2)重复序列仅限于特定的染色体区域；以及3)由于转座速率较低，散布的元件将以与其他中性DNA相似的速度进化。选择新大陆叶鼻蝙蝠是因为被研究的类群的单系性被很好地记录下来，并且它们在核型进化的速率和类型上表现出极端的情况。检查方法将包括对基因组文库进行系统发育筛选，以确定快速进化的重复序列的数量和种类。染色体的位置和移动将通过对原位杂交数据的分支分析来记录。

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.