title: Different evolutionary fates of recently integrated human and chimpanzee LINE-1 retrotransposons.
abstract: The long interspersed element-1 (LINE-1 or L1) is a highly successful retrotransposon in mammals. L1 elements have continued to actively propagate subsequent to the human-chimpanzee divergence, approximately 6 million years ago, resulting in species-specific inserts. Here, we report a detailed characterization of chimpanzee-specific L1 subfamily diversity and a comparison with their human-specific counterparts. Our results indicate that L1 elements have experienced different evolutionary fates in humans and chimpanzees within the past approximately 6 million years. Although the species-specific L1 copy numbers are on the same order in both species (1200-2000 copies), the number of retrotransposition-competent elements appears to be much higher in the human genome than in the chimpanzee genome. Also, while human L1 subfamilies belong to the same lineage, we identified two lineages of recently integrated L1 subfamilies in the chimpanzee genome. The two lineages seem to have coexisted for several million years, but only one shows evidence of expansion within the past three million years. These differential evolutionary paths may be the result of random variation, or the product of competition between L1 subfamily lineages. Our results suggest that the coexistence of several L1 subfamily lineages within a species may be resolved in a very short evolutionary period of time, perhaps in just a few million years. Therefore, the chimpanzee genome constitutes an excellent model in which to analyze the evolutionary dynamics of L1 retrotransposons.
authors.affiliation: Department of Biological Sciences, Biological Computation and Visualization Center, Center for BioModular Multi-Scale Systems, Louisiana State University, 202 Life Sciences Building, Baton Rouge, LA 70803, USA.
authors.forename: Jungnam
authors.initials: J
authors.lastname: Lee
authors.forename: Richard
authors.initials: R
authors.lastname: Cordaux
authors.forename: Kyudong
authors.initials: K
authors.lastname: Han
authors.forename: Jianxin
authors.initials: J
authors.lastname: Wang
authors.forename: Dale J
authors.initials: DJ
authors.lastname: Hedges
authors.forename: Ping
authors.initials: P
authors.lastname: Liang
authors.forename: Mark A
authors.initials: MA
authors.lastname: Batzer
mesh_terms: D020121:5' Untranslated Regions; D000818:Animals; D019143:Evolution, Molecular; D006071:Gorilla gorilla / Q000235:genetics; D006801:Humans; D020084:Long Interspersed Nucleotide Elements; D008969:Molecular Sequence Data; D002679:Pan troglodytes / Q000235:genetics*; D010802:Phylogeny; D011110:Polymorphism, Genetic; D011148:Pongo pygmaeus / Q000235:genetics; D013045:Species Specificity; D013997:Time Factors
chemical_list: D020121:5' Untranslated Regions