Microevolution - Definition, Causes, Examples, and Differences from Macroevolution
Microevolution refers to small changes in the gene pool of a population over a short period, driven by factors like mutation, gene flow, genetic drift, and natural selection. It is part of the NEET Biology Syllabus and helps learners understand how species adapt and evolve. Vedantu breaks down these core ideas in a simple way, focusing on how traits shift within populations and why such shifts matter for evolution.
What is Microevolution?
An allele is any one of two or more possible versions of a gene located at a specific spot on a chromosome. In simpler terms, it represents a physical trait that appears within a population and causes small, gradual changes. These shifts are often subtle and may not show up clearly in the next generation. About the Hardy-Weinberg principle, allele frequencies stay constant unless at least one of its conditions is violated—when that happens, the frequencies shift and microevolution takes place.
Microevolution can set the stage for speciation, laying the groundwork for macroevolution through the buildup of small genetic changes. Both microevolution and macroevolution rely on similar mechanisms but differ mainly in how long they take. While microevolution occurs over shorter periods, macroevolution unfolds over much larger timescales.
The genetic changes seen in microevolution stem from processes like natural selection, artificial selection, mutation, genetic drift, and gene flow. In biology, population genetics provides a mathematical framework for studying these shifts, while ecological genetics looks at how they happen in the natural world.
Microevolution Examples
Well-known examples include the development of resistance to herbicides and pesticides, as well as antibiotic resistance in bacteria. Specific instances are-
Whiteflies are becoming resistant to pesticides.
Mosquitoes evolving resistance to DDT
HIV strains resisting antiviral drugs
Gonorrheal bacteria strains adapting to penicillin
Causes of Microevolution
Changes in a population’s gene pool between generations—often noted as shifts in allele frequencies—arise from four main evolutionary forces-
Mutations- These generate new alleles and can be sparked by viruses, replication errors, UV radiation, or mutagenic chemicals.
Genetic Drift- Random fluctuations in allele frequencies, which have a stronger impact on smaller populations.
Gene Flow- The movement of alleles between populations through migration, increasing genetic diversity in the receiving population.
Natural Selection- Occurring either naturally or through artificial means, this process typically unfolds over long periods, leading to observable changes.
Nonrandom mating can also influence microevolution by affecting how alleles are combined and passed on.
Microevolution and Macroevolution
Microevolution refers to the small-scale shifts in a population’s gene pool over time, resulting in subtle changes within the same species. Macroevolution, on the other hand, encompasses larger, more significant transformations that can lead to entirely new species, different from their ancestral forms.
A key distinction lies in the genetic data requirements- microevolutionary changes do not necessarily need a major increase in functional genetic information, while macroevolution typically does—making it more challenging to achieve. Although variations occur across all life-forms, including microbes, animals, plants, and humans, each group differs in the degree and type of diversification it undergoes.
Difference Between Microevolution and Macroevolution
Essential Study Materials for NEET UG Success
FAQs on What is Microevolution? Definition, Examples, Causes and Differences For NEET
1. What is Microevolution in Simple Terms?
Microevolution is a small-scale change in the gene pool of a population over a short period. It involves shifts in allele frequencies due to factors like mutation, genetic drift, gene flow, and natural selection.
2. How Does Microevolution Differ from Macroevolution?
Microevolution focuses on small changes within a species, while macroevolution deals with large-scale changes that can form entirely new species. Macroevolution usually takes much longer and may involve more significant genetic alterations.
3. What are the Main Causes of Microevolution?
The primary drivers include-
Mutations- Introduce new alleles.
Genetic Drift- Random changes in small populations.
Gene Flow- Movement of alleles between populations.
Natural Selection- Alleles become more or less common based on survival and reproduction success.
4. How Do Microevolutionary Changes Affect a Species?
These small changes can lead to variations in traits, such as color or size, making a population more adaptable. Over time, these adaptations may contribute to the development of new species (macroevolution).
5. Can We Observe Microevolution Directly?
Yes, it can often be seen in real-time. Examples include bacteria developing antibiotic resistance or insects becoming resistant to pesticides. These changes can happen over a few generations.
6. Why is Microevolution Important in NEET Biology?
Understanding microevolution helps students grasp how species adapt and evolve. It’s a key concept in the NEET Biology syllabus, offering insight into broader evolutionary processes and the genetic basis of variation.
7. Does Nonrandom Mating Influence Microevolution?
Yes. When mating isn’t random, certain alleles may be passed on more frequently, further shaping the gene pool and accelerating small evolutionary changes.
8. How Does Microevolution Relate to the Hardy-Weinberg Principle?
Microevolution occurs when any conditions of the Hardy-Weinberg equilibrium (such as no mutation, random mating, or large population size) are broken. This leads to changes in allele frequencies within a population.
9. Can Microevolution Eventually Lead to New Species?
Yes. Although microevolution involves small-scale changes, these can accumulate over time. When enough genetic differences build up, speciation—a key feature of macroevolution—can occur.
10. Is Microevolution Always Beneficial?
Not necessarily. Changes in the gene pool can be beneficial, neutral, or even harmful, depending on how they affect an organism’s survival and reproductive success.
11. Why is Microevolution Important in Studying Diseases?
Microbes and viruses can quickly undergo microevolution, leading to antibiotic or antiviral resistance. Understanding these small-scale changes is vital for developing effective treatments and controlling outbreaks.
