No description available.

No description available.

No description available.

No description available.

Malgache, qui es-tn?' This question seeking the ancestry o f the Malagasy remains unanswered five centuries after the debate on the proposed hypotheses of Malagasy origins began. Historical, archaeological, linguistic and some genetic data suggest two major sources o f ancestry: Africa and Indonesia, with minor contributions from Arabia, India and China, but the evidence for the suggestions is sparse and inconclusive. All Malagasy, irrespective of their ethnic backgrounds speak a common language, Malagasy, but differences in physical appearance and culture suggests that they may have different ancestral histories. The goals of this study are to utilize genetic variation present in the Malagasy in conjunction with available data to reconstruct their prehistory and to provide evidence confirming and/or refining existing theories concerning their prehistory. The genetic profiles of eleven of the eighteen Malagasy ethnic groups, a South African Indian and six African populations were compared at thirteen loci; eight autosomal and five Y chromosomal. The markers include four STR loci each on the autosornes (HUMCSF1PO, HUMTH01, HUMCD4 and an (AC)n repeat m the DRD2 gene) and on the Y chromosome (DYS3.93, DYS19, DYS390 and DYS391), two Alu polymorphisms (CD4-/Uw and YAP) and three RtLP loci within the DRD2 gene, Some o f these loci were used to derive autosomal an-j Y chromosome haplotypcs, Population trees as well as principal component analyses- bast-d ba the different data sets consistently revealed very close affinities between the eleven Malagasy groups examined, The intermediate clustering of the Malagasy between African and South Asians also reaffirms that these two groups have contributed significantly to the Malagasy gene pool. Admixture estimates made using autosomal data suggest that approximately 50% o f the Malagasy gene pool is derived from an African source while Y chromosome data indicates an African contribution o f at least 60%. Networks constructed using Y chromosome haplotypes identified a ‘Malagasy-specific’ haplotype cluster. A divergence time of 2864 years (95% confidence intervals, 1227 - 7472 years) is estimated for this cluster which is consistent with archaeological data suggesting that the colonization of Madagascar occurred within the past 3000 years. Both autosomal and Y chromosomal ihta from the present study supports a recent common ancestry for the Malagasy from founders whose gene pool contained contributions from Indonesians and Africans.

No description available.

The purpose of this study was to investigate the polymorphism of a group of related compounds. Special emphasis was placed upon the temperature at which transitions occurred and a possible correlation of these temperatures with other properties of the compounds.

Thesis (M.A. (South African National Bioinformatics Institute, Faculty of Natural Sciences))--University of the Western Cape, 2009. / Includes bibliographical references (89-106).

No description available.

A Californian population of the Yellow Monkey Flower, Mimulus guttatus Fischer ex D.C., contains a floral fragrance polymorphism such that the plants can be divided into two classes: fragrant and non-fragrant. This thesis has examined the effects of the fragrance polymorphism on the natural pollinators of M. guttatus, with a view to investigating the role and evolutionary significance of floral fragrance in apidophilous plants. Published work by many researchers has suggested that a fragrance polymorphism in an apidophilous chasmogamous plant would lead to reduced inter-phenotype pollinator movements due to the phenomenon of odour-constancy, and hence to genetic divergence and possibly sympatric speciation. Alternatively, if the fragrance phenotypes differed in pollinator attractiveness, the more attractive phenotype would have a selective advantage, and would therefore eventually become fixed. Both of these possible scenarios have been explored in the course of this project, both by investigation of bee foraging behaviour on experimental plots containing fragrant and non-fragrant Mimulus plants, and by investigation of the fitnesses of the two phenotypes in the natural population and under glasshouse conditions. It was found that the two phenotypes did not differ significantly in terms of measured fitness, and that in the natural population there was no evidence of reduced gene-flow between fragrant and non-fragrant plants. Experimental plot results showed no evidence of odour-constancy by bees, but revealed that some bumblebee species discriminated weakly between the two phenotypes. Pollinators were found to be visiting Mimulus flowers for pollen, and variation in plant pollen production had significant effects on within-plant foraging behaviour. However, bees failed to learn to associate fragrance phenotype with pollen production, in contrast to previously published research that has demonstrated that bees readily learn to associate fragrance phenotype with nectar rewards, suggesting that pollen-collecting bees may respond differently to floral cues than nectar-collecting bees. For a variable such as floral fragrance to have evolutionary significance it is essential that the character is heritable, and part of the investigation has concentrated on investigating the heritability and penetrance of the character. It was found that inheritance of fragrance is best explained by a simple additive genetic model, and that fragrance production is dominant to absence of fragrance. The possibility that this fragrance polymorphism has been previously influenced by other pollen vectors and the population's potential for switching from bee-pollination to alternative pollen vectors is discussed.