Natural selection

Definition

Natural selection is the process through which certain traits become more or less common in a population based on their impact on the survival and reproduction of individuals. This mechanism plays a critical role in evolution, as individuals with advantageous traits are more likely to survive and pass those traits to future generations, shaping genetic diversity over time. It helps explain variations in traits such as copy number variations and the distribution of alleles within populations.

5 Must Know Facts For Your Next Test

1. Natural selection can lead to both microevolution and macroevolution, influencing short-term and long-term changes in populations.
2. Variation in a population is essential for natural selection to occur; without genetic diversity, there would be no traits for selection to act upon.
3. Natural selection acts on phenotypes, which are the observable traits of an organism, rather than directly on genotypes.
4. The process of natural selection can result in speciation when populations become isolated and adapt to different environments over time.
5. Natural selection is one of the key mechanisms of evolution, alongside mutation, gene flow, and genetic drift.

Review Questions

• How does natural selection influence copy number variations within a population?
  • Natural selection influences copy number variations by favoring certain genetic variants that confer advantages in survival and reproduction. For example, if an organism possesses a copy number variation that enhances its ability to thrive in a particular environment, those individuals are more likely to reproduce successfully. Over time, this can increase the prevalence of beneficial copy number variations within the population while deleterious variations may diminish.
• In what ways can natural selection disrupt Hardy-Weinberg equilibrium in a population?
  • Natural selection disrupts Hardy-Weinberg equilibrium by altering allele frequencies due to differential survival and reproduction among individuals with varying phenotypes. When certain traits confer advantages or disadvantages, those alleles associated with beneficial traits increase in frequency while those linked to detrimental traits decrease. This change violates the assumptions of Hardy-Weinberg equilibrium, particularly the assumption that all genotypes have equal chances of survival and reproduction.
• Evaluate the role of natural selection in shaping genetic diversity and adaptation within a population over time.
  • Natural selection plays a fundamental role in shaping genetic diversity by promoting the survival of individuals with advantageous traits, leading to changes in allele frequencies over generations. As environmental conditions change or new challenges arise, natural selection drives adaptation by favoring those traits that enhance survival and reproductive success. This ongoing process contributes not only to the development of new adaptations but also maintains genetic diversity, ensuring that populations remain resilient in the face of changing environments.

Related terms

Adaptive Traits: Characteristics that enhance an organism's ability to survive and reproduce in a specific environment.

Gene Flow: The transfer of genetic material between populations, which can influence allele frequencies and affect natural selection.

Genetic Drift: A random process that can lead to changes in allele frequencies in small populations, potentially countering the effects of natural selection.