News: Evolution of the Mitochondrial Genome in Snakes.

Evolution of the Mitochondrial Genome in Snakes: Gene Rearrangements
and Phylogenetic Relationships

http://7thspace.com/headlines/298817/evolution_of_the_mitochondrial_genome_in_snakes_gene_rearrangements_and_phylogenetic_relationships.html

Snakes as a major reptile group display a variety of morphological
characteristics pertaining to their diverse behaviours. Despite
abundant analyses of morphological characters, molecular studies using
mitochondrial and nuclear genes are limited.

As a result, the phylogeny of snakes remains controversial. Previous
studies on mitochondrial genomes of snakes have demonstrated
duplication of the control region and translocation of trnL to be two
notable features of the alethinophidian (all serpents except
blindsnakes and threadsnakes) mtDNAs.

Our purpose is to further investigate the gene organizations,
evolution of the snake mitochondrial genome, and phylogenetic
relationships among several major snake families.

Results: The mitochondrial genomes were sequenced for four taxa
representing four different families, and each had a different gene
arrangement. Comparative analyses with other snake mitochondrial
genomes allowed us to summarize six types of mitochondrial gene
arrangement in snakes.

Phylogenetic reconstruction with commonly used methods of phylogenetic
inference (BI, ML, MP, NJ) arrived at a similar topology, which was
used to reconstruct the evolution of mitochondrial gene arrangements
in snakes.

Conclusions: The phylogenetic relationships among the major families
of snakes are in accordance with the mitochondrial genomes in terms of
gene arrangements.

The gene arrangement in Ramphotyphlops braminus mtDNA is inferred to
be ancestral for snakes. After the divergence of the early
Ramphotyphlops lineage, three types of rearrangements occurred.

These changes involve translocations within the IQM tRNA gene cluster
and the duplication of the CR. All phylogenetic methods support the
placement of Enhydris plumbea outside of the (Colubridae + Elapidae)
cluster, providing mitochondrial genomic evidence for the familial
rank of Homalopsidae.

Author: Jie Yan, Hongdan Li and Kaiya Zhou
Credits/Source: BMC Genomics 2008, 9:569

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Bob.

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