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Phylogenetic Analysis of Phenotypic Covariance Structure. II. Reconstructing Matrix Evolution
Scott J. Steppan
Vol. 51, No. 2 (Apr., 1997), pp. 587-594
Published by: Society for the Study of Evolution
Stable URL: http://www.jstor.org/stable/2411130
Page Count: 8
You can always find the topics here!Topics: Covariance, Evolution, Phylogenetics, Biological taxonomies, Population parameters, Matrices, Genetics, Phylogeny, Population structure, Divergent evolution
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A modified minimum evolution approach is used to estimate covariance matrices for hypothetical ancestors. Branch lengths are calculated as the mean disparity in corresponding ancestor-descendent covariances. Branches are longest leading to terminal populations and subspecies, while interspecific branches are relatively short, indicating a general conservation of covariance structure among species despite a high degree of intraspecific variability. Absolute deviations in covariance structure are not correlated with phenotypic divergence. Interpreted in light of other studies, the analyses suggest that deviations in covariance structure are most strongly associated with the formation of diagnosably distinct taxa and stochastic sampling of genotypes at the population level. There is no evidence for restructuring of phenotypic covariance structure in association with reproductive isolation. The results suggest that phenotypic covariances are dynamic over short time scales and do not support attempts to extrapolate genetic covariance structure to explain or predict macroevolutionary change. This study further demonstrates that branch lengths, which are not usually analyzed in detail, contain valuable evolutionary information complementary to that residing in the branching pattern.
Evolution © 1997 Society for the Study of Evolution