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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Effects of Phylogeny on Structural Correlations of Vertebrate Eyes

Jacobs, Amanda YL 01 January 2014 (has links)
Common ancestry prevents scientists from using traditional statistical tests in dimensional comparisons that span entire clades. Data in these cases are non-independent, so a variety of special statistical methods have been developed specifically for phylogenetic comparative analyses. A phylogenetic least squares method was used to re-examine four published datasets detailing structural correlates of eyes while factoring in the different ways the phylogeny was expected to affect the covariance in trait values. All analyses were carried out in a strict phylogenetic context, using published time-calibrated phylogenies and the statistical platform R. Specifically, Pagel’s lambda was used to determine how much of an influence phylogeny had on each pair of traits. In all tested soft and hard tissue correlations, the phylogeny of the species slightly altered the trend lines of the measurements, compared to lines that did not take phylogenetic relationship into consideration. These results do not contradict previous results, but further work needs to be done to determine the implications that significant phylogenetic signal has on subsequent analyses. Future studies should account for phylogenetic relationships which have been shown to influence the relationship between traits.

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