The term microevolution was first used by a botanist called Robert Greenleaf Leavitt in the journal Botanical gazette in 1909. An allele is a variant form of a specific gene which is found at certain locations on chromosomes. In simple words, we can write it as a physical trait that expresses a population of indistinct and fine changes. But these changes don’t reflect on the progeny.
In context to the Hardy-Weinberg equilibrium, it can be defined as the allele frequencies will change if any of the criteria of Hardy-Weinberg equilibrium is not satisfied.
What is Microevolution?
The microevolution definition can be written as, the change in the allele frequency for a particular period of time in a population.
Microevolution can lead to speciation which serves as a raw material for the macroevolution. Hence we can tell that they both follow similar procedures but the difference is they have different time scales. Microevolution occurs in a short period of time when compared to macroevolution.
Example of microevolution in everyday life:
The examples of microevolution that we can see in our everyday life are as follows:
Examples of microevolution in humans:
Newborn babies have smaller jaws.
Extra bones are found in the legs and feet of newborn children.
Babies are born with an extra artery in their arms.
Causes of Microevolution:
The causes of microevolution
Mutations: Mutation is the change in the sequence of DNA which is caused due to radiations, viruses, chemicals, replication and during meiosis.
Errors are introduced in the DNA replication during the polymerization of the second strand. Mutation can affect the phenotype of an organism if they occur within the protein-coding sequence of a gene.
Mutation in terms of changes in DNA sequences are of several different types, it can either have no effect on the gene, alter the product of a gene, or prevent the gene from functioning.
Through genetic recombination, a mutation can involve a large number of DNA that gets duplicated.
Genetic drift: Genetic drift is the change in the relative frequency in which an allele occurs in the population. Genetic drift can affect large populations in smaller proportions and small populations in the larger proportion.
It is an evolutionary process that leads to the change in the allele frequencies over time. This may cause alleles to disappear completely.
The changes that occur due to genetic drift are not controlled by the environment or adaptive pressures but they may help maintain reproductive success.
Gene flow: The exchange of genes between the populations of the same species is called gene flow.
The examples of the gene flow within the same species are migration, breeding of organisms, and exchange of pollen-grains. In between the species are horizontal gene transfer and the formation of hybrid organisms.
Migration may change the allele frequencies; immigration may add the genetic material into the gene pool, and emigration may remove the genetic material. Two diverging populations are the barriers to reproduction, gene flow can add genetic differences and the process will slow down.
Mule is a hybrid that is produced by the fusion of gametes in between horses and donkeys. But this hybrid is generally infertile due to the presence of different sets of chromosomes that fail to pair up during the process of meiosis. But hybridization is an important means of speciation in plants because the plants react easily to polyploidy when compared to animals.
The transfer of genetic material from one organism to another which is not its offspring is called horizontal gene transfer.
Selection: The process in which the heritable traits make it common for an organism to survive and reproduce in a population over successive generations.
If the selection occurs naturally, it is natural selection, and if it is chosen by humans, it is artificial selection. However, natural selection plays a dominant role in selection.
Natural selection acts on the phenotype.
Microevolution and Macroevolution
Microevolution can be used to refer to the alterations that occur in a gene pool of the population over a period of time which leads to small changes in the same species. In the macroevolution, the produced offspring are totally different as compared to their ancestors.
The changes that are observed in the variations in microevolution do not require a statistically significant increase in the genetic data. However, that is not the case in macroevolution, the genetic variations in macroevolution require a statistically significant increase in the genetic data.
Difference Between Microevolution and Macroevolution
Microevolution varies from macroevolution.
Population genetics is the branch of biology which deals with the study of the process of microevolution. Microevolution is all about how the populations differ from one another. Speciation can be considered as a link between macroevolution and microevolution.