Microevolution

Definition

Microevolution refers to the small-scale changes in allele frequencies within a population over time, driven by mechanisms such as natural selection, genetic drift, mutation, and gene flow. These changes can result in variations that ultimately influence the traits and survival of organisms in a population. It illustrates how populations adapt to their environments and evolve in response to selective pressures.

5 Must Know Facts For Your Next Test

1. Microevolution occurs over relatively short time scales and can be observed in real-time within populations, unlike macroevolution which involves larger evolutionary changes over longer periods.
2. Natural selection is one of the primary drivers of microevolution, as it favors individuals with advantageous traits that improve survival and reproduction rates.
3. Genetic drift can lead to significant changes in allele frequencies in small populations, potentially resulting in the loss of genetic diversity.
4. Mutations introduce new alleles into a population's gene pool, providing the raw material for evolutionary change during microevolution.
5. Gene flow, or the movement of alleles between populations through migration, can alter allele frequencies and promote genetic diversity among populations.

Review Questions

• How do mechanisms like natural selection and genetic drift contribute to microevolution within a population?
  • Natural selection contributes to microevolution by favoring individuals with traits that enhance survival and reproduction, leading to increased frequencies of those advantageous alleles over generations. Genetic drift, on the other hand, results in random fluctuations in allele frequencies due to chance events, which can disproportionately affect small populations. Together, these mechanisms demonstrate how microevolution shapes the genetic makeup of populations in response to environmental pressures and random events.
• In what ways can microevolutionary changes be measured or observed in populations?
  • Microevolutionary changes can be measured through tracking changes in allele frequencies over time using techniques like DNA analysis and population sampling. Researchers may also observe phenotypic variations in traits influenced by these allele frequency changes. For example, studies on antibiotic resistance in bacteria showcase how rapid microevolution occurs as resistant strains become more common due to selective pressures from antibiotic use.
• Evaluate the implications of microevolution for understanding larger evolutionary processes and biodiversity.
  • Microevolution provides critical insights into larger evolutionary processes by illustrating how small genetic changes can accumulate over time, potentially leading to speciation or significant adaptations. Understanding microevolution allows scientists to explore the mechanisms driving biodiversity and how organisms adapt to changing environments. This knowledge is vital for conservation efforts and predicting how species might respond to rapid environmental changes, emphasizing the interconnectedness of all living organisms through their evolutionary histories.

Related terms

allele frequency:

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

genetic drift:

A mechanism of evolution that involves random changes in allele frequencies due to chance events, particularly affecting small populations.

natural selection:

The process by which organisms better adapted to their environment tend to survive and reproduce more than those less suited to the environment.