Genetic drift and mutational hazard in the evolution of salamander genomic gigantism
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Salamanders have the largest nuclear genome sizes among tetrapods and, with the exception of lungfishes, among vertebrates as a whole. Lynch and Conery (2003) have proposed the mutational hazard hypothesis to explain variation in genome size and complexity. Under this hypothesis, non-coding DNA imposes a selective cost by increasing the target for degenerative mutations, i.e. the mutational hazard. Expansion of non-coding DNA, and thus genome size, is expected to be driven by increased levels of genetic drift and/or decreased mutation rates; the former determines the efficiency with which excess ...