Macroevolution is the idea that all organisms are derived from one common ancestor and are derived from the same DNA as this ancestor (Bailey, 2017). Weight gain or loss is not associated with genetic evolution as these are traits which vary over time and does not get passed on genetically to the next generation (Bailey, 2017). Natural selection does not act on an individual but rather the population as a whole and this process is influenced by genetic variations and the environment (Bailey, 2017). The environment is an unstable factor and organisms which contain variable genetic information are better off at adapting to the changes (Bailey, 2017). Individuals which possess traits which make them survive will be passed onto the offspring and make the offspring more favourable in the population (Bailey, 2017). Genetic variation occurs in a population through DNA mutation and sexual reproduction (Bailey, 2017). Genetic recombination occurs through the process of meiosis which produces combinations on a single chromosome (Bailey, …show more content…
Many phenotypes are possible due to the interactions of several alleles available in polygenic inheritance (Bailey, 2017). Polygenic traits exhibit incomplete dominance and Mendelian traits which exhibit complete dominance (Bailey, 2017). The phenotypes which arise from the polygenic inheritance is a mixture of each parent allele (Bailey, 2017). If the polygenic traits were to be plotted on a population distribution curve it would take on the shape of a bell curve where the middle region indicates the mixed alleles and the sides of the curve show the more dominant traits (Bailey, 2017). Eye colour is a trait caused by polygenic inheritance and is influenced by up to 16 different genes (Bailey, 2017). Eye colour is determined by the brown colour pigment melanin (Bailey, 2017). Chromosome 15 (OCA2 and HERC2) is the location of 2 of the genes which determine eye colour (Bailey,