Microevolution

Definition

Microevolution refers to the small-scale changes in allele frequencies within a population over time, resulting in subtle evolutionary shifts. These changes can occur through processes such as mutation, gene flow, genetic drift, and natural selection, ultimately leading to variations within a species. Understanding microevolution helps explain how populations adapt to their environments and evolve over generations.

5 Must Know Facts For Your Next Test

1. Microevolutionary changes can be observed within relatively short time frames, such as in response to environmental pressures or selective breeding.
2. Mutations are the original source of genetic variation that can lead to microevolution, providing new alleles for natural selection to act upon.
3. Gene flow can occur when individuals migrate between populations, introducing new alleles and altering allele frequencies.
4. Genetic drift can cause significant changes in small populations, especially after events like bottlenecks or founder effects where only a few individuals establish a new population.
5. Microevolution can lead to speciation if changes accumulate over time, eventually resulting in distinct populations that cannot interbreed.

Review Questions

• How do mechanisms like mutation and gene flow contribute to microevolution?
  • Mutation introduces new genetic variations into a population by altering DNA sequences, which can create new alleles. Gene flow occurs when individuals from different populations interbreed, bringing in new alleles that can change the overall allele frequency of the recipient population. Together, these mechanisms create the genetic diversity necessary for microevolution to occur, allowing populations to adapt to changing environments.
• Discuss how natural selection operates within the context of microevolution and its impact on population adaptation.
  • Natural selection acts on existing variations within a population by favoring individuals with traits that enhance their survival and reproductive success. Over time, these advantageous traits become more common within the population, leading to microevolution. This process allows populations to adapt to their environments as certain traits become more favorable under specific conditions, ultimately shaping the evolutionary trajectory of the species.
• Evaluate the role of genetic drift in microevolution and how it differs from natural selection in influencing population dynamics.
  • Genetic drift plays a significant role in microevolution by causing random fluctuations in allele frequencies due to chance events, especially in small populations. Unlike natural selection, which is a non-random process driven by environmental pressures favoring certain traits, genetic drift can lead to the loss of genetic variation and may cause alleles to become fixed or lost regardless of their adaptive value. This randomness can significantly impact the genetic structure of populations over time and may lead to divergent evolutionary paths.

Related terms

allele frequency: The relative frequency of an allele at a genetic locus in a population, often expressed as a proportion or percentage.

natural selection:

The process by which organisms that are better adapted to their environment tend to survive and reproduce more successfully than others.

genetic drift:

A random change in allele frequencies within a population, often having a more pronounced effect in small populations.