Meeting Abstract

P1.142  Wednesday, Jan. 4   Global annotation and molecular evolutionary analysis of genomic repeats in the Painted Turtle, Chrysemys picta MEDLIN , Alexandra/M.*; COLE, Amanda/M.; SHEDLOCK, Andrew/M. ; College of Charleston; College of Charleston; College of Charleston

The analysis of genome-scale information from the sister group of mammals, Reptilia, is presently closing a large gap in the study of vertebrate biology. Turtles are of central importance to this effort in that they have been difficult to place accurately in the amniote tree of life, they exhibit a number of unique phenotypic and life history traits among vertebrates, and are threatened globally by a variety of human impacts on the environment. Annotating genomic repeats by sequence alignment to a reference database provides a means for testing alternative models of molecular evolution and can thereby describe forces that have shaped our own genomes uniquely as compared to other amniotes. We annotated global repeat content for the full set of genomic sequence reads generated for the painted turtle, C. picta, the first turtle species having its complete genome assembled. Sequence divergence values reveal differential age distributions among major repeat subfamilies suggesting relatively young active mobile elements are still driving turtle genomic diversity whereas distributions skewed toward higher mean values suggest the presence of numerous distinct lineages of older inactive repeats that can be viewed as molecular fossils embedded in turtle chromosomes. The present study reveals that alternative modes of evolution are likely operating in different turtle repeat lineages whose proliferation and persistence cannot be easily explained by strict vertical inheritance of single source genes, such as seen for the dominant form of interspersed repeats in the human genome and that contrasts with the largely inactive compact repetitive DNA landscape of birds.