Genetic variation

Importance of genetic diversity

More variation in populations the more likely that some individuals will have traits that give them a survival advantage.

Species with low variation are susceptible to disease and climate change

If in a population no individual has the ability to adapt to a change then a population risks going extinct

Genotype variation:

Process of meiosis and fertilisation create variations in the genotype of offspring

In meiosis the following things create genetic variation:

Crossing over (AKA recombination)

Occurs between prophase 1/metaphase 1, is where homologous chromosomes pair up with each other and exchange different segments of genetic material to form recombinant chromosomes

Random assortment (AKA independent assortment)

Refers to the way maternal and paternal chromosomes get organized into daughter cells during gamete formation

Non-disjunction

Is the failure of homologous chromosomes or sister chromatids to separate properly during cell division
Causes gamete to have an extra chromosome or only part of a chromosome
E.g. Down syndrome
Trisomy refers to an extra chromosome in the diploid cell
Monosomy refers to a missing chromosome from typical diploid set

Fertilisation

Is a random event, as there is no way of knowing which sperm will fertilise which egg
Therefore any sperm cell from the male can fuse with any egg from the female, resulting in the sharing of genetic information, which in turn creates genetic variation

Other sources of variation

Mutation

Are the ultimate source of variation in a population. They can create new alleles or genes
If mutations are neutral or beneficial they can slowly spread through a population