Methods for the analysis of DNA variation
PCR reaction, molecular markers (microsatellites, SNPs) and elements of sequence analysis. This part of the course will include theoretical lessons as also practice in laboratory.
Mechanisms of evolutionary changes
- What is a population?
- How to describe a population: genotypic and allelic frequencies.
- The Hardy-Weinberg law (HW), chi-square test, estimator of genetic diversity (HE), Wahlund effect, genetic divergence among populations (FST). Applications of the HW law. The role of the evolutionary forces on the level and structure of genetic variation in forest populations: mutations, genetic drift, migration, founder effect, bottleneck effect, effective population size (Ne), selection (the fundamental theorem of selection, selection against the dominant phenotype, selection against the recessive phenotype, selection in favor of the heterozygotes), recombination. Interaction between the evolutionary forces: equilibrium between migration and genetic drift, between migration and selection, among migration, drift and selection. Inbreeding: definition and calculation of the inbreeding coefficient. Inbreeding depression and heterosis.
- The genetic basis of quantitative traits.
- Fundamental statistics: mean, variance, standard deviation; covariance and correlation.
- Phenotypic value, genotypic value and environmental deviation. The model of Mather. Population mean, average effect of the alleles, average effect of allelic substitution, breeding value. Dominance deviations. The partitioning of the phenotypic variance: genetic variance (additive and dominance) and environmental variance. Genotype x environment interaction. Heritability (broad sense and narrow sense). Resemblance between relatives and covariance. Selection for quantitative traits: selection differential, intensity of selection, selection gain.
Factors influencing genetic variations within populations
Estimates of genetic diversity from genetic markers and quantitative traits. The role of Population Size,
longevity, high levels of outcrossing, migration between populations (by pollen and seed flow): selection in changing environments: balancing selection. Mating system in forest trees. mechanisms promoting high levels of outcrossing (protoginy, proterandry, poliembriony, auto-incompatibility systems). Factors leading to unusually low levels of outcrossing. Plants density; patterns of cross-fertilization within populations. spatial and temporal genetic structure within populations Practical implications of within-population genetic diversity: genetic improvements under natural regeneration systems. Seed collections. in Natural Populations.
Provenance, clinal and ecotipic variation. Provenance x Environment Interaction. Experimental methods used to study geographic variation: genetic markers , short-term seedling tests, long-term provenance trials patterns of geographic variation in forest trees. Implications of geographic variation for Seed Transfer“ Domestic” and “Darwinian” fitness. Seed-zones.
Relevance of the forest genetic resources. The in situ and ex situ strategies for the conservation of genetic resources. Sampling strategies. Core collections.
Phenotypic mass selection. Comparison between seedling forestry and clonal forestry. Genetic gain, choice of traits and indirect response. Selection for multiple traits. General combining ability (GCA) and Specific Combining Ability (SCA). Genetic tests: Incomplete-pedigree mating designs and complete pedigree (Full-sib Family) mating designs. Recurrent selection for GCA. Advanced-generation breeding strategies (elite population + main population, multiple populations, sublines).