Browsing by Subject "Haplopappus gracilis"
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Item A cytogenetic analysis of a pericentric inversion in Hapolopappus Graclis(Texas Tech University, 1996-08) Keck, Catherine LeeHaplopappus gracilis is a smaU, annual member of the family Compositae with three chromosomal races. The standard race (n=2) is distributed in the southwestern United States from southern Colorado to New Mexico and Arizona (Jackson 1973). The standard karyotype consists of a long pair of median centric chromosomes designated A and two chromosomes with submedian centromeres, secondary constrictions and satellites designated as chromosome B (Jackson 1957). A Mexican n=2 race, confined to the Big Bend area of Texas and Chihuahua and Durango, Mexico, is distinguished by a change in centromere position caused by a centric transposition on chromosome A (Jackson 1973). The third race (n=3) normally occurs in three smaU contiguous towns in Arizona. It was derived from hybrids between the n=2 standard and Mexican transposition races by chromosome breakage (Jackson 1992). In Wickenberg, Arizona, a standard chromosome population was found to include a pericentric inversion on chromosome B. This caused a change in chromosome morphology from a normal acrocentric to a median centromere position, which was used as a marker for the inversion. The inversion includes the centromere and excludes the NOR region and satellite. Breaks caused by the inversion appear to be in nonfunctional regions because a maximum poUen fertihty of 89.45% occurs in the inversion homozygotes. Artificial crosses were performed by R. C. Jackson to obtain a homozygote inversion stock for this smdy. Photographs of the standard, inversion heterozygote, and inversion homozygote karyotypes are shown in Figures 1-3.Item A Genetic Study of Tricotyly in Haplopappus Gracilis(Texas Tech University, 1975-08) Guess, Robert EdgarNot Available.Item Allozyme and quantitative life history variation among populations and ecological races of "Haplopappus gracilus" (Compositae)(Texas Tech University, 1988-08) Freiley, Kenneth JTo 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.Item An analysis of the patterns of environmental and electrophoretic variability in populations of Haplopappus gracilis (Compositae) and related species(Texas Tech University, 1978-12) Spohn, Ronald TerryNOT AVAILABLEItem Cytogenetics of a centric transposition of populations of Haplopappus gracilis(Texas Tech University, 1979-08) Cequea Ruiz, Hernan PastorNot availableItem Natural Hybridization Between Two Chromosome Races of Haplopappus Gracilis: Evidence for Pollen Selection(Texas Tech University, 1972-08) Jordan, Robert GlenNot Available.Item Quantification of gametic selection in a greenhouse population of Haplopappus gracilis(Texas Tech University, 1973-12) Boren, Billy DeanNot available