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Accueil du site → Doctorat → États-Unis → 1988 → Allozyme and quantitative life history variation among populations and ecological races of "Haplopappus gracilus" (Compositae)

Texas Tech University (1988)

Allozyme and quantitative life history variation among populations and ecological races of "Haplopappus gracilus" (Compositae)

Freiley, Kenneth J.

Titre : Allozyme and quantitative life history variation among populations and ecological races of "Haplopappus gracilus" (Compositae).

Auteur : Freiley, Kenneth J.

Université de soutenance : Texas Tech University

Grade : Doctor of Philosophy 1988

Résumé
To estimate the extent of evolutionary divergence and evolutionary potential among natural populations of Hapiopappus gracilis. genetic and morphological differentiation was investigated using the techniques of enzyme electrophoresis, quantitative genetics, and multivariate morphometrics. Variation at nine loci coding for seven enzymes was characterized in nine populations using starch gel electrophoresis and variation in 14 morphological and life history characters was examined using univariate and multivariate statistics. Components of phenotypic variation in six characters were approximated by an analysis of half-sibs in two populations and estimates of heritabilities (h^2) and genetic correlations (rA) were calculate. The morphological and allozymic data sets exhibited little concordance in respect to distance statistics. Although morphoiogicai and iife liistory characters indicated distinct differentiation of populations along ecological race lines. there was no apparent pattern in genetic distance relationships based on allozymic variation. This lack of concordance is interpreted as support for the neutral mutation-genetic drift theory of molecular evolution. Lower heritabilities and little detectable additive genetic variance were present in life history traits of a low desert population compared to a population inhabiting a more mesic habitat. This difference reflects the classical quantitative genetic theory which predicts reduced levels of additive genetic variance for fitness-reiated characters in populations exposed to comparatively strong selection forces.

Mots clés : Haplopappus gracilis ; Plant population genetics ; Plants – Evolution

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Page publiée le 3 juin 2013, mise à jour le 29 décembre 2016