6.2.11 - Factors Affecting The Evolution of a Species

• Population genetics is a sub field of genetics that deals with genetic differences within and between populations and is part of evolutionary biology.
• Evolution can be defined as the change in allele frequencies in a population and occurs by natural selection.
• Individuals within a species vary because they have different alleles, which are introduced by mutation and migration.
• Predation, disease and selection pressure create a struggle for survival. Some individuals within a population will be better adapted than others to the selection pressures, due to their differences in genotypes and phenotypes.
• Individuals carrying alleles that make them more adapted to a change in environment have an increased chance of survival, an advantageous allele, so are more likely to survive and reproduce and pass on the advantageous allele.
• This means that a greater proportion of the next generation inherit the advantageous allele, so the frequency of the advantageous allele increases between generations.
• Over time, allele frequencies within the population’s gene pool will change. This is natural selection, and it may also contain constancy of a species as well as leading to a new species.
• The gene pool can be defined as the total information from all the genes and alleles of the breeding individuals in a population at a particular time.
• The gene pool‘s composition changes from one generation to the next as the relative proportions of alleles vary.
• If there is a consistent change in allele frequency (the proportion of organisms in the population carrying a particular allele) then a population is evolving