Linked Life Data

10093216

Source:http://linkedlifedata.com/resource/pubmed/id/10093216

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1999-4-13
pubmed:abstractText
The transition/transversion (ti/tv) rate ratios are estimated by pairwise sequence comparison and joint likelihood analysis using mitochondrial cytochrome b genes of 28 primate species, representing both the Strepsirrhini (lemurs and lories) and the Anthropoidea (monkeys, apes, and humans). Pairwise comparison reveals a strong negative correlation between estimates of the ti/tv ratio and the sequence distance, even when both are corrected for multiple substitutions. The maximum-likelihood estimate of the ti/tv ratio changes with the species included in the analysis. The ti/tv bias within the lemuriform taxa is found to be as strong as in the anthropoids, in contradiction to an earlier study which sampled only one lemuriform. Simulations show the surprising result that both the pairwise correction method and the joint likelihood analysis tend to overcorrect for multiple substitutions and overestimate the ti/tv ratio, especially at low sequence divergence. The bias, however, is not large enough to account for the observed patterns. Nucleotide frequency biases, variation of substitution rates among sites, and different evolutionary dynamics at the three codon positions can be ruled out as possible causes. The likelihood-ratio test suggests that the ti/tv rate ratios may be variable among evolutionary lineages. Without any biological evidence for such a variation, however, we are left with no plausible explanations for the observed patterns other than a possible saturation effect due to the unrealistic nature of the model assumed.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0022-2844
pubmed:author
pubmed:issnType
Print
pubmed:volume
48
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
274-83
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
Estimation of the transition/transversion rate bias and species sampling.
pubmed:affiliation
Department of Biology (Galton Laboratory), University College London, England. z.yang@ucl.ac.uk
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S.