INTRODUCTION
Genetic variation occurs when the genetic makeup of organisms within a population changes. Genes are inherited DNA segments that contain protein-making instructions. Alleles are different versions of genes that determine distinct traits that can be passed down from parents to offspring.
Genetic variation refers to differences in the genetic makeup of individuals within a population.
Natural selection necessitates genetic diversity. Organisms with environmental selection are better able to adapt to their surroundings and pass on their genes through natural selection.
Major sources of variation include mutations, gene flow, and sexual reproduction.
DNA mutation causes genetic variation by altering the genes of individuals in a population.
Genetic variation occurs when new individuals with different gene combinations enter a population.
Sexual reproduction promotes variable gene combinations in a population, resulting in genetic variation.
Genetic variation can be seen in eye colour, blood type, animal camouflage, and plant leaf modification.
Natural selection and biological evolution are heavily reliant on genetic variation. Natural selection does not occur by chance, but genetic variations in a population do. Natural selection occurs as a result of genetic differences in a population interacting with its environment. The environment determines which genetic variations are more advantageous or better suited for survival. As organisms with these environmentally selected genes survive and reproduce, more favourable traits are passed on to the population.
Genetic Variation Causes
The primary sources of genetic variation are DNA mutation, gene flow (the movement of genes from one population to another), and sexual reproduction. Because environments are inherently unstable, genetically diverse populations will be better able to adapt to changing circumstances than genetically diverse populations.
A mutation is defined as a change in the DNA sequence. In some cases, variations in gene sequences can be beneficial to an organism. The vast majority of genetic mutations result in traits that are neither advantageous nor disadvantageous. Mutations cause genetic variation by changing genes and alleles in a population. They could have an impact on a single gene or an entire chromosome. Although mutations change an organism’s genotype (genetic make-up), they do not always change its phenotype.
Flow of Genes: Gene flow occurs when organisms migrate to a new environment and introduce new genes into the population. It is also known as gene migration. The presence of new alleles in the gene pool enables the creation of new gene combinations. The emigration of organisms from a population can also alter gene frequencies. New organisms introduced into a population can help organisms adapt to changing environmental conditions. Organisms leaving a population may result in a loss of genetic diversity.
Sexual reproduction promotes genetic diversity by producing various gene combinations. Meiosis is the process by which sex cells or gametes are formed. During fertilisation, alleles in gametes are separated and randomly united, resulting in genetic variation. Genetic recombination occurs during meiosis during crossing over or the swapping of gene segments in homologous chromosomes.
Sources of Genetic Variation
Gene duplication, mutation, and other processes can result in the creation of new genes and alleles, increasing genetic variation. New genetic variation can be created within generations in a population, so a population with a high reproduction rate will most likely have a lot of genetic variation. Existing genes, on the other hand, can be rearranged in novel ways during sexual reproduction as a result of chromosomal crossing over and recombination. The main sources of genetic variation are the formation of new alleles, changes in gene number or position, rapid reproduction, and sexual reproduction.
Origins of genetic variation
Genetic variation is the difference in DNA sequences between individuals within a population. Variation occurs in germ cells i.e. sperm and egg, and also in somatic (all other) cells. Only variation that arises in germ cells can be inherited from one individual to another and so affect population dynamics, and ultimately evolution. Mutations and recombination are major sources of variation.
What are mutations?
Mutations are the original source of genetic variation. A mutation is a permanent alteration to a DNA sequence. De novo (new) mutations occur when there is an error during DNA replication that is not corrected by DNA repair enzymes. It is only once the error is copied by DNA replication, and fixed in the DNA that it is considered to be a mutation. Mutations may be beneficial to the organism; deleterious (harmful) to the organism; or neutral (have no effect on the fitness of the organism).
Somatic mutations can accumulate in our cells and are mostly harmless. They can lead to local changes in tissues such as moles appearing on the skin, and can also have more serious effects – for example leading to cancer. In this course we focus on heritable genetic variation, i.e. variation that occurs in germ cells.
CONCLUSION
As a result, we conclude that genetic variations affecting gene activity or protein function can cause an organism to develop different traits. If a trait is advantageous and aids an individual’s survival and reproduction, it is more likely to be passed down to future generations (a process known as natural selection).
The primary sources of genetic variation are DNA mutation, gene flow (the movement of genes from one population to another), and sexual reproduction. Because environments are inherently unstable, genetically diverse populations will be better able to adapt to changing circumstances than genetically diverse populations.