The population genomics of a fast evolver: high levels of diversity, functional constraint, and molecular adaptation in the tunicate Ciona intestinalis.
Genome Biol Evol
; 4(8): 740-9, 2012.
Article
en En
| MEDLINE
| ID: mdl-22745226
ABSTRACT
Phylogenomics has revealed the existence of fast-evolving animal phyla in which the amino acid substitution rate, averaged across many proteins, is consistently higher than in other lineages. The reasons for such differences in proteome-wide evolutionary rates are still unknown, largely because only a handful of species offer within-species genomic data from which molecular evolutionary processes can be deduced. In this study, we use next-generation sequencing technologies and individual whole-transcriptome sequencing to gather extensive polymorphism sequence data sets from Ciona intestinalis. Ciona is probably the best-characterized member of the fast-evolving Urochordata group (tunicates), which was recently identified as the sister group of the slow-evolving vertebrates. We introduce and validate a maximum-likelihood framework for single-nucleotide polymorphism and genotype calling, based on high-throughput short-read typing. We report that the C. intestinalis proteome is characterized by a high level of within-species diversity, efficient purifying selection, and a substantial percentage of adaptive amino acid substitutions. We conclude that the increased rate of amino acid sequence evolution in tunicates, when compared with vertebrates, is the consequence of both a 2-6 times higher per-year mutation rate and prevalent adaptive evolution.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Ciona intestinalis
/
Evolución Molecular
/
Genómica
/
Biodiversidad
Límite:
Animals
Idioma:
En
Revista:
Genome Biol Evol
Asunto de la revista:
BIOLOGIA
/
BIOLOGIA MOLECULAR
Año:
2012
Tipo del documento:
Article
País de afiliación:
Francia