Genome Biology and Evolution Advance Access published online on May 5, 2009
Genome Biology and Evolution, doi:10.1093/gbe/evp007
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Independent Mammalian Genome Contractions Following the KT Boundary
1 Department of Biology, Indiana University, Bloomington, IN 47405
2 School of Informatics, Indiana University, Bloomington, IN 47405
3 To whom correspondence should be addressed. Email: milynch{at}indiana.edu
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Abstract |
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Although it is generally accepted that major changes in the earth's history are significant drivers of phylogenetic diversification and extinction, such episodes may also have long-lasting effects on genomic architecture. Here we show that widespread reductions in genome size have occurred in multiple lineages of mammals subsequent to the Cretaceous-Tertiary boundary, whereas there is no evidence for such changes in other vertebrate, invertebrate, or land-plant lineages. Although the mechanisms remain unclear, such shifts in mammalian genome evolution may be a consequence of an increase in the efficiency of selection against excess DNA resulting from post-KT population-size expansions. Independent historical changes in genome architecture in diverse lineages raise a significant challenge to the idea that genome size is finely tuned to achieve adaptive phenotypic modifications, and suggest that attempts to use phylogenetic analysis to infer ancestral genome sizes may be problematical.
Keywords: genome evolution, genome size, KT boundary, mammalian evolution, mobile elements, pseudogenes, retrotransposons
Received January 13, 2009; Revised April 23, 2009; Accepted April 24, 2009