Microevolution Definition

“The change in allele frequency over a period of time in a particular population is defined as Microevolution”

What Is Microevolution?

An allele is one of the two or more versions of a mutation at a certain location on a chromosome that is typically known, it is a variant form of a specific gene. To simply put into other words, it is a physical trait that gets expressed in a population causing fine and indistinct changes. However, the immediate changes do not reflect predominantly on the progeny. It can also be defined in the context of the Hardy-Weinberg equilibrium – “the allele frequencies change if any of the criteria of Hardy-Weinberg equilibrium is not fulfilled”.

It is also important to note that microevolution can perhaps lead to speciation, serving as a raw material for the process of macroevolution which is caused due to accumulation of changes from the process of microevolution. Hence, it can be deduced that both microevolution and macroevolution follow similar procedures, the difference being the time scale. In terms of evolution, this change occurs in a shorter frame in comparison to macroevolution.

The change that microevolution entails can be attributed to the following processes – Natural and artificial selection, Mutation, Genetic drift and Gene flow

There is a stream in Biology known as Population genetics that renders a mathematical explanation for the learnings of microevolution while ecological genetics deals with the observation of the process in the wild.

Microevolution Examples

Some examples of microevolution through the process of natural selection are herbicide resistance, pesticide resistance, antibiotic resistance and so on. Few other generally noticeable evolutionary instances of microevolution are the bacterial strains incorporating the property of resistance to antibiotics.

Few other examples are as listed below:

  • Resistance to pesticides by whiteflies
  • Resistance to DDT by mosquitoes
  • HIV strains developing resistance to antiviral medicines
  • Gonorrheal bacteria strains developing resistance to penicillin

Causes of Microevolution

The change that occurs in the gene pool from one to another generation, the change in the allele frequencies are attributed to the 4 fundamental evolutionary forces –

  • Mutations – this is known as one of the most likely causes of variations causing new alleles. A mutation is as a result of viruses, erroneous replication, UV rays and some mutagenic chemicals
  • Genetic drift – observed in smaller populations where evolution is as a result of haphazard changes in the allele frequency in a population.
  • Gene flow – it is the transfer of genes when the alleles are physically moving in a population. It takes place when an individual migrates between populations. The process causes an increase in the genetic diversity of a population
  • Natural selection – it can be artificial or natural and takes hundreds and thousands of years to take place and cause remarkable changes

Sometimes, the cause for microevolution is also attributed to Nonrandom mating.

Microevolution and Macroevolution

While microevolution can be used to refer to the alteration in a gene pool of the population over a period of time leading to minute changes in the entity of the same species, macroevolution is the changes in an entity eventually producing totally different species significantly differing from their ancestors.

Microevolution varies from macroevolution. Changes observed in the variations in microevolution does not require a statistically significant increase in the genetic data (functional). However, that is not the case in macroevolution. The genetic variations in macroevolution require a statistically significant increase in the genetic data (functional), which is a challenge to accomplish.

In Spite of the variations being noted in almost all life-forms, be it, microbes, animals, plants or humans, the only distinguishing factor between each is the diversification it entails.

Difference between microevolution and macroevolution

The following table depicts some key differences between microevolution and macroevolution:

Attributes Microevolution Macroevolution
Evolutionary changes Occurring on a small scale within a specific single population Occurring on a large scale beyond the level of single species
Leads to Alterations in the gene pool resulting in the intraspecies genetic change New species formation
Genetic data Is rearranged or altered New species are formed as a result of deletion, addition in the structure of the gene
Time frame Changes occur over a short period of time Changes occur over a long time period
Example New strains of flu viruses, the peppered moth Development of feathers, development of vertebrates from invertebrates

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