@ARTICLE{TreeBASE2Ref19036,
author = {Ashley N. Egan and Jeff J. Doyle},
title = {A Comparison of Global, Gene-Specific, and Relaxed Clock Methods in a Comparative Genomics Framework: Dating the Polyploid History of Soybean (Glycine max) },
year = {2010},
keywords = {Glycine; divergence times; polyploidy; comparative genomics; molecular clock; relaxed clock; synonymous substitution rates},
doi = {},
url = {http://},
pmid = {},
journal = {Systematic Biology},
volume = {},
number = {},
pages = {},
abstract = {Abstract. ? It is widely recognized that many genes and lineages do not adhere to a molecular clock, yet molecular clocks are commonly used to date divergences in comparative genomic studies. We test the application of a molecular clock across genes and lineages in a phylogenetic framework, utilizing 12 genes linked in a 1-Megabase region on chromosome 13 of soybean (Glycine max), homoeologous copies of these genes formed by polyploidy in Glycine, and orthologous copies in G. tomentella, Phaseolus vulgaris, and Medicago truncatula. We compare divergence dates estimated by two methods each in three frameworks: a global molecular clock with a single rate across genes and lineages using full and approximate likelihood methods based on synonymous substitutions; a gene-specific clock assuming rate constancy over lineages but allowing a different rate for each gene; and a relaxed molecular clock where rates may vary across genes and lineages, estimated under penalized likelihood and Bayesian inference. We use the cumulative variance across genes as a means of quantifying precision. Our results suggest that divergence dating methods produce results that are correlated, but that older nodes are more variable and more difficult to estimate with precision and accuracy. We also find that models incorporating less rate heterogeneity estimate older dates of divergence than more complex models, as node age increases. A mixed model nested ANOVA testing the effects of framework, method, and gene found that framework had a significant effect on the divergence date estimates but that most variation among dates is due to variation among genes, suggesting a need to further characterize and understand the evolutionary phenomena underlying rate variation within genomes, among genes, and across lineages. }
}
Citation for Study 10632
Citation title:
"A Comparison of Global, Gene-Specific, and Relaxed Clock Methods in a Comparative Genomics Framework: Dating the Polyploid History of Soybean (Glycine max) ".
Study name:
"A Comparison of Global, Gene-Specific, and Relaxed Clock Methods in a Comparative Genomics Framework: Dating the Polyploid History of Soybean (Glycine max) ".
This study is part of submission 10622
(Status: Published).
Citation
Egan A.N., & Doyle J. 2010. A Comparison of Global, Gene-Specific, and Relaxed Clock Methods in a Comparative Genomics Framework: Dating the Polyploid History of Soybean (Glycine max). Systematic Biology, .
Authors
-
Egan A.N.
(submitter)
801-367-9148
-
Doyle J.
Abstract
Abstract. ? It is widely recognized that many genes and lineages do not adhere to a molecular clock, yet molecular clocks are commonly used to date divergences in comparative genomic studies. We test the application of a molecular clock across genes and lineages in a phylogenetic framework, utilizing 12 genes linked in a 1-Megabase region on chromosome 13 of soybean (Glycine max), homoeologous copies of these genes formed by polyploidy in Glycine, and orthologous copies in G. tomentella, Phaseolus vulgaris, and Medicago truncatula. We compare divergence dates estimated by two methods each in three frameworks: a global molecular clock with a single rate across genes and lineages using full and approximate likelihood methods based on synonymous substitutions; a gene-specific clock assuming rate constancy over lineages but allowing a different rate for each gene; and a relaxed molecular clock where rates may vary across genes and lineages, estimated under penalized likelihood and Bayesian inference. We use the cumulative variance across genes as a means of quantifying precision. Our results suggest that divergence dating methods produce results that are correlated, but that older nodes are more variable and more difficult to estimate with precision and accuracy. We also find that models incorporating less rate heterogeneity estimate older dates of divergence than more complex models, as node age increases. A mixed model nested ANOVA testing the effects of framework, method, and gene found that framework had a significant effect on the divergence date estimates but that most variation among dates is due to variation among genes, suggesting a need to further characterize and understand the evolutionary phenomena underlying rate variation within genomes, among genes, and across lineages.
Keywords
Glycine; divergence times; polyploidy; comparative genomics; molecular clock; relaxed clock; synonymous substitution rates
External links
About this resource
- Canonical resource URI:
http://purl.org/phylo/treebase/phylows/study/TB2:S10632
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- Show BibTeX reference
@ARTICLE{TreeBASE2Ref19036,
author = {Ashley N. Egan and Jeff J. Doyle},
title = {A Comparison of Global, Gene-Specific, and Relaxed Clock Methods in a Comparative Genomics Framework: Dating the Polyploid History of Soybean (Glycine max) },
year = {2010},
keywords = {Glycine; divergence times; polyploidy; comparative genomics; molecular clock; relaxed clock; synonymous substitution rates},
doi = {},
url = {http://},
pmid = {},
journal = {Systematic Biology},
volume = {},
number = {},
pages = {},
abstract = {Abstract. ? It is widely recognized that many genes and lineages do not adhere to a molecular clock, yet molecular clocks are commonly used to date divergences in comparative genomic studies. We test the application of a molecular clock across genes and lineages in a phylogenetic framework, utilizing 12 genes linked in a 1-Megabase region on chromosome 13 of soybean (Glycine max), homoeologous copies of these genes formed by polyploidy in Glycine, and orthologous copies in G. tomentella, Phaseolus vulgaris, and Medicago truncatula. We compare divergence dates estimated by two methods each in three frameworks: a global molecular clock with a single rate across genes and lineages using full and approximate likelihood methods based on synonymous substitutions; a gene-specific clock assuming rate constancy over lineages but allowing a different rate for each gene; and a relaxed molecular clock where rates may vary across genes and lineages, estimated under penalized likelihood and Bayesian inference. We use the cumulative variance across genes as a means of quantifying precision. Our results suggest that divergence dating methods produce results that are correlated, but that older nodes are more variable and more difficult to estimate with precision and accuracy. We also find that models incorporating less rate heterogeneity estimate older dates of divergence than more complex models, as node age increases. A mixed model nested ANOVA testing the effects of framework, method, and gene found that framework had a significant effect on the divergence date estimates but that most variation among dates is due to variation among genes, suggesting a need to further characterize and understand the evolutionary phenomena underlying rate variation within genomes, among genes, and across lineages. }
}
- Show RIS reference
TY - JOUR
ID - 19036
AU - Egan,Ashley N.
AU - Doyle,Jeff J.
T1 - A Comparison of Global, Gene-Specific, and Relaxed Clock Methods in a Comparative Genomics Framework: Dating the Polyploid History of Soybean (Glycine max)
PY - 2010
KW - Glycine; divergence times; polyploidy; comparative genomics; molecular clock; relaxed clock; synonymous substitution rates
UR - http://dx.doi.org/
N2 - Abstract. ? It is widely recognized that many genes and lineages do not adhere to a molecular clock, yet molecular clocks are commonly used to date divergences in comparative genomic studies. We test the application of a molecular clock across genes and lineages in a phylogenetic framework, utilizing 12 genes linked in a 1-Megabase region on chromosome 13 of soybean (Glycine max), homoeologous copies of these genes formed by polyploidy in Glycine, and orthologous copies in G. tomentella, Phaseolus vulgaris, and Medicago truncatula. We compare divergence dates estimated by two methods each in three frameworks: a global molecular clock with a single rate across genes and lineages using full and approximate likelihood methods based on synonymous substitutions; a gene-specific clock assuming rate constancy over lineages but allowing a different rate for each gene; and a relaxed molecular clock where rates may vary across genes and lineages, estimated under penalized likelihood and Bayesian inference. We use the cumulative variance across genes as a means of quantifying precision. Our results suggest that divergence dating methods produce results that are correlated, but that older nodes are more variable and more difficult to estimate with precision and accuracy. We also find that models incorporating less rate heterogeneity estimate older dates of divergence than more complex models, as node age increases. A mixed model nested ANOVA testing the effects of framework, method, and gene found that framework had a significant effect on the divergence date estimates but that most variation among dates is due to variation among genes, suggesting a need to further characterize and understand the evolutionary phenomena underlying rate variation within genomes, among genes, and across lineages.
L3 -
JF - Systematic Biology
VL -
IS -
ER -