In laboratory cultures of Drosophila melanogaster derived from an African population, the quantities of six out of seven enzymes (G6PD, IDH, GPDH, ME, MDH, PGM and ADH) were higher in homozygotes than they were in Adh -SS. In crosses between Adh -FF and Adh -SS flies, the differences segregated as co-dominant alleles of a single Mendelian gene closely linked, or identical, to the Adh locus. The generality of these associations was suggested by the study of a French population with a very different history and genetic background. The possibility that the associations were caused by artefacts of the immunodiffusion techniques, or to a linked inversion t), was excluded. Possible ways by which the Adh locus may affect the quantities of other enzymes are discussed.

Evolution and the genetics of populations. Vol. 1. Genetic and biométrie foundations.

Synergistic Effect of Adh Alleles in Drosophila melanogaster

Various ways of deducing cladistic relationships between taxa have been proposed but whether one can find phylogenetic relationships from phenetic similarity is debatable (Sokal and Sneath, 1963, chapter 8; Hull, 1964; Jardine, 1971). Recently computer methods have been used for obtaining branching sequences, i.e., cladograms (Edwards and Cavalli-Sforza, 1964; Cavalli-Sforza and Edwards, 1967; Camin and Sokal, 1965; Kluge and Farris, 1969; Morishima, 1969), but these rest upon basic intuitive assumptions. In the particular case of the cultivated oats, there is no need to deduce such cladistic relationships because they have been elaborated for most of the cultivars (Baum, 1969a; Baum, 1972a). The objective of the present study was to choose a probable ancestor of the predomesticated cultivated oats. This was done by drawing a morphological picture, based on micromorphologic attributes. Another objective was to postulate, with respect to these attributes, which one of the existing wild taxa is most similar to this ancestor.

Extrapolation of the predomesticated hexaploid cultivated oats.

The Chinese winter wheat cultivar Lumai 21 showed slow resistance to powdery mildew. To estimate the number of genes and its heritability, 200 lines of F2:3 and F2:4 populations derived from the cross between Lumai 21 and Jingshuang 16 (susceptible) and their parents were planted at Beijing and Anyang, Henan for disease evaluation in 2005-06 and 2006-07 cropping seasons. The resistance was analyzed based on both quantitative and qualitative genetic models. At least 3-4 resistance genes were detected in the 2 populations. The broadsense heritability of resistance was 0.53–0.78. Transgressive segregation indicated that Jingshuang 16 might hold 1 minor gene for resistance, and Lumai 21 contained at least 2-3 genes, accordingly.

Heritability and number of genes controlling slow-mildewing resistance in wheat cultivar Lumai 21

Determinants of clinical responses in asthma

Theoretical work has shown that deleterious mutations may explain many evolutionary phenomena, but the role they play depends on their specific properties, including the overall rate at which they occur in the genome and the distribution of their selection ( s) and dominance ( h) coefficients. However, accurate estimates for these parameters from a range of species are still lacking. In this thesis, two distinct approaches were used to quantify the mutational process. In Chapter 3, a novel DNA-based method was used to infer levels of evolutionary constraints in theDrosophilagenome by comparing rates of nucleotide substitution in noncoding and putatively neutrally evolving DNA. Introns were found to have a significantly higher rate of substitution than synonymous sites, and, when introns were used as a neutrally evolving standard, constraint in the 500bp of intergenic DNA upstream and downstream of coding regions was found to be about 44%. Selection against mutations in intergenic DNA should therefore make a substantial contribution to the mutational load in Drosophila. Secondly, a fitness-based approach was used to estimate mutational parameters in lines ofCaenorhabditis elegans containing large numbers of deleterious homozygous EMSinduced mutations. In Chapter 4, replicated inbred sublines were produced for eight mutant lines, and the performance of the sublines, the mutant lines and the wild-type strain was measured for three fitness-related traits. The number of mutations per line was then estimated for each trait by applying a modified version of the Castle-Wright estimator and a maximum likelihood (ML) method. Both the Castle-Wright and the ML analyses suggest that most of the variation among sublines was due to a small number ( ∼1.5–2.5) of largeeffect mutations. Given that each line is expected to have a large number of mutations, this supports the hypothesis that many have very small (but still deleterious) effects. In Chapter 5, the average dominance coefficient of mildly deleterious mutations ( h) was estimated from a selection of 19 relatively high fitness mutant lines by comparing the performance of heterozygotes and homozygotes to the wild-type for three fitness-related traits (viability, productivity, and relative fitness). There was very little net heterozygous or

Evolution and the genetics of populations. Vol. 1. Genetic and biométrie foundations.

Citations

Synergistic Effect of Adh Alleles in Drosophila melanogaster

Extrapolation of the predomesticated hexaploid cultivated oats.

Heritability and number of genes controlling slow-mildewing resistance in wheat cultivar Lumai 21

Determinants of clinical responses in asthma

Quantifying the mutational process

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