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Three crocodilian genomes reveal ancestral patterns of evolution among archosaurs
Journal article   Open access   Peer reviewed

Three crocodilian genomes reveal ancestral patterns of evolution among archosaurs

Richard E Green, Edward L Braun, Joel Armstrong, Dent Earl, Ngan Nguyen, Glenn Hickey, Michael W Vandewege, John A St John, Salvador Capella-Gutiérrez, Todd A Castoe, …
Science (American Association for the Advancement of Science), Vol.346(6215), 1254449
12/12/2014
DOI: 10.1126/science.1254449
PMCID: PMC4386873
PMID: 25504731
url
https://doi.org/10.1126/science.1254449View
Published (Version of record) Open Access

Abstract

To provide context for the diversification of archosaurs--the group that includes crocodilians, dinosaurs, and birds--we generated draft genomes of three crocodilians: Alligator mississippiensis (the American alligator), Crocodylus porosus (the saltwater crocodile), and Gavialis gangeticus (the Indian gharial). We observed an exceptionally slow rate of genome evolution within crocodilians at all levels, including nucleotide substitutions, indels, transposable element content and movement, gene family evolution, and chromosomal synteny. When placed within the context of related taxa including birds and turtles, this suggests that the common ancestor of all of these taxa also exhibited slow genome evolution and that the comparatively rapid evolution is derived in birds. The data also provided the opportunity to analyze heterozygosity in crocodilians, which indicates a likely reduction in population size for all three taxa through the Pleistocene. Finally, these data combined with newly published bird genomes allowed us to reconstruct the partial genome of the common ancestor of archosaurs, thereby providing a tool to investigate the genetic starting material of crocodilians, birds, and dinosaurs.
Dinosaurs - classification Molecular Sequence Annotation Transcriptome Molecular Sequence Data Birds - classification Reptiles - genetics Phylogeny Reptiles - classification Sequence Analysis, DNA DNA Transposable Elements Biological Evolution Genetic Variation Sequence Alignment Alligators and Crocodiles - classification Animals Dinosaurs - genetics Conserved Sequence Alligators and Crocodiles - genetics Birds - genetics Genome Evolution, Molecular

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