Title

Dynamic Nucleotide Mutation Gradients And Control Region Usage In Squamate Reptile Mitochondrial Genomes

Keywords

D-loop; Genome replication; Genome structure-function; Snakes; Substitution gradients

Abstract

Gradients of nucleotide bias and substitution rates occur in vertebrate mitochondrial genomes due to the asymmetric nature of the replication process. The evolution of these gradients has previously been studied in detail in primates, but not in other vertebrate groups. From the primate study, the strengths of these gradients are known to evolve in ways that can substantially alter the substitution process, but it is unclear how rapidly they evolve over evolutionary time or how different they may be in different lineages or groups of vertebrates. Given the importance of mitochondrial genomes in phylogenetics and molecular evolutionary research, a better understanding of how asymmetric mitochondrial substitution gradients evolve would contribute key insights into how this gradient evolution may mislead evolutionary inferences, and how it may also be incorporated into new evolutionary models. Most snake mitochondrial genomes have an additional interesting feature, 2 nearly identical control regions, which vary among different species in the extent that they are used as origins of replication. Given the expanded sampling of complete snake genomes currently available, together with 2 additional snakes sequenced in this study, we reexamined gradient strength and CR usage in alethinophidian snakes as well as several lizards that possess dual CRs. Our results suggest that nucleotide substitution gradients (and corresponding nucleotide bias) and CR usage is highly labile over the ∼200 m.y. of squamate evolution, and demonstrates greater overall variability than previously shown in primates. The evidence for the existence of such gradients, and their ability to evolve rapidly and converge among unrelated species suggests that gradient dynamics could easily mislead phylogenetic and molecular evolutionary inferences, and argues strongly that these dynamics should be incorporated into phylogenetic models. Copyright © 2010 S. Karger AG, Basel.

Publication Date

4-1-2010

Publication Title

Cytogenetic and Genome Research

Volume

127

Issue

2-4

Number of Pages

112-127

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1159/000295342

Socpus ID

77951880867 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/77951880867

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