Correlated response and sexual dimorphism in bidirectional selection experiments

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dc.contributor.authorCarte, Ira Franklinen
dc.contributor.committeechairSiegel, Paul B.en
dc.contributor.committeememberGaines, James A.en
dc.contributor.committeememberHinkelmann, Klaus H.en
dc.contributor.committeememberHowes, C. E.en
dc.contributor.committeememberWest, David A.en
dc.contributor.departmentGeneticsen
dc.date.accessioned2014-03-14T21:15:01Zen
dc.date.adate2010-06-12en
dc.date.available2014-03-14T21:15:01Zen
dc.date.issued1968-02-05en
dc.date.rdate2010-06-12en
dc.date.sdate2010-06-12en
dc.description.abstractThis dissertation involved two experiments, (1) the study of realized heritabilities of correlated traits, and (2) the study of the inheritance of sexual dimorphism or body weight. The first experiment included data from four generations of double two-way selection for body weight and breast angle at eight weeks of age. Breast angle was considered a correlated trait in the weight subpopulation and body weight a correlated trait in the angle subpopulation. There was a significant divergence between lines for both selected traits. The response to direct selection for breast angle was asymmetrical with the response in the narrow direction being greater then that in the broad direction. The response of body weight to two-way selection was symmetrical through the F₄ generation. Divergence of body weight between the lines selected for breast angle was significant in the F₁, F₃, and F₄ generations. Divergence of breast angle between the lines selected for body weight was significant in the F₂ and subsequent generations. Heritabilities of the unselected traits were obtained by the cumulative difference between lines divided by the expected secondary selection differential and by the regression of the cumulative difference between lines on expected secondary selection differential. The correlated realized heritability of breast angle was greater in the weight lines than was the correlated realized heritability for body weight in the angle lines. Examination of the components of the correlated realized heritability showed that they were the ratio of the genetic to phenotypic covariances of the two traits. The second experiment involved the investigation of sex dimorphism for body weight at eight weeks of age. The heritability estimate for sex dimorphism of this trait was .02, and the genetic correlation of it in males and females was .98. The genetic variability (.02) in sex dimorphism was evidenced by a greater response in males to selection for eight-week body weight than in females. The biological reason for this was additive sex-linkage.en
dc.description.degreePh. D.en
dc.format.extent85, 2 leavesen
dc.format.mediumBTDen
dc.format.mimetypeapplication/pdfen
dc.identifier.otheretd-06122010-020659en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-06122010-020659/en
dc.identifier.urihttp://hdl.handle.net/10919/38601en
dc.language.isoenen
dc.publisherVirginia Techen
dc.relation.haspartLD5655.V856_1968.C35.pdfen
dc.relation.isformatofOCLC# 41061112en
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectgenetic correlationen
dc.subject.lccLD5655.V856 1968.C35en
dc.titleCorrelated response and sexual dimorphism in bidirectional selection experimentsen
dc.typeDissertationen
dc.type.dcmitypeTexten
thesis.degree.disciplineGeneticsen
thesis.degree.grantorVirginia Polytechnic Instituteen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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