Truth in Science

5.4 Mechanism of change

 

Heterozygotes as important reservoirs of genetic variation.

Mutation as a source of genetic variation. Gene mutation (limited to base deletions and substitutions) and chromosome mutation (aneuploidy and polyploidy); mutagenic agents.

The significance of polyploidy in plant breeding.

The concept of the gene pool and population genetics: the application of the Hardy-Weinberg equation to calculate allele and genotype frequencies in an outbreeding population. The Hardy-Weinberg principle and the influence of mutation, non-random fertilisation, migration and selection on allele and/or genotype frequencies.

Selection (stabilising and directional) and its contribution to the maintenance of polymorphic populations and evolutionary change in populations. Geographic isolation leading to allopatric speciation; other secondary isolating mechanisms.

5.5 Taxonomy

The concept of the species based on breeding compatibility and the production of fertile offspring.

A hierarchical classification based on presumed phylogeny: organisms are named in a binary fashion consisting of genus and species; genera are organised into a hierarchy of higher taxa (family, order, class in ascending order); classes are arranged into phyla; phyla are classified into kingdoms. The five kingdom system of classification.