Types of Variation

Section 1: Understanding Variation

Variation is the difference in characteristics observed within the individuals of a species.
It is the result of different genetic information and different environmental influences.

Section 2: Genetic Variation

Genetic variation occurs due to the differing genetic material present in each individual organism.
It happens because of differences in individuals’ chromosomes or in alleles of genes.
Genetic variations can be caused by gene mutations, genetic recombination during sexual reproduction, or through random fertilisation.
Gene mutations can happen spontaneously, this produces new alleles of a gene.
Genetic recombination happens during meiosis, where maternal and paternal chromosomes pair and swap sections.
Random fertilisation during sexual reproduction also increases genetic variation.

Section 3: Environmental Variation

Environmental variation is the result of an individual’s experiences or its surroundings.
These variations are not genetic and hence are not passed on to the next generation.
Examples could include variations in height and weight, which might be affected by diet and lifestyle.

Section 4: Discontinuous and Continuous Variation

There are two types of variations seen within a population - discontinuous and continuous variation.
Discontinuous variation results in individuals falling into a number of distinct categories. Examples include blood group, eye colour, and presence or absence of a widow’s peak in humans.
Unlike discontinuous variation, continuous variation results in a range of phenotypes between two extremes. Examples include height, weight, and skin colour in humans.

Section 5: Importance of Variation

Variation is crucial as it enhances the survival of a species during environmental changes; this concept is known as survival of the fittest.
Species with more genetic variation have more chances for adaptation and survival than those with less genetic diversity.
This is due to the increased likelihood of some individuals possessing alleles enabling them to survive under changing conditions, these individuals will then pass these beneficial alleles on to their offspring.