Natural Selection

Definition

Natural selection is the process by which organisms that are better adapted to their environment tend to survive and reproduce more successfully than others. This concept, introduced by Charles Darwin, emphasizes how certain traits become more common in a population due to their advantages in survival and reproduction, ultimately shaping the evolution of species over time.

5 Must Know Facts For Your Next Test

1. Natural selection operates on existing variations within a population; it does not create new traits but favors those that are advantageous.
2. The process of natural selection can lead to speciation, where new species arise from populations that adapt to different environments.
3. Environmental pressures, such as predation, climate changes, and availability of resources, play a crucial role in determining which traits are favored through natural selection.
4. Natural selection can be observed in both short-term adaptations (like pesticide resistance in insects) and long-term evolutionary changes (like the development of new species).
5. While natural selection is a key mechanism of evolution, it works alongside other processes like mutation, gene flow, and genetic drift to shape the genetic landscape of populations.

Review Questions

• How does natural selection contribute to the adaptation of species in changing environments?
  • Natural selection contributes to the adaptation of species by favoring individuals with traits that enhance their ability to survive and reproduce in specific environments. As environmental conditions change, those organisms best suited for the new circumstances are more likely to thrive and pass on their advantageous traits to future generations. Over time, this leads to a population that is better adapted to its environment, showcasing the dynamic nature of natural selection.
• In what ways can natural selection lead to the emergence of new species?
  • Natural selection can lead to speciation through processes such as adaptive radiation or reproductive isolation. When populations of a species become separated by geographical barriers or ecological niches, they may experience different selective pressures. Over time, these populations adapt to their unique environments through natural selection, which may result in significant genetic divergence. Eventually, if these differences become pronounced enough, they can no longer interbreed, leading to the formation of new species.
• Evaluate the impact of natural selection on reproductive behaviors and how this relates to evolutionary fitness.
  • Natural selection significantly impacts reproductive behaviors by favoring those strategies that enhance reproductive success and ensure the survival of offspring. For example, traits such as mating displays or parental care may evolve because they increase an organism's chances of attracting mates or successfully raising young. These behaviors are linked directly to evolutionary fitness, as individuals exhibiting favorable reproductive strategies are more likely to pass on their genes. Understanding this relationship illustrates how behavior is a vital component of natural selection and evolutionary processes.

Related terms

Adaptation: A characteristic that enhances the survival and reproductive success of an organism in its environment.

Survival of the Fittest: A phrase that summarizes the outcome of natural selection, where 'fittest' refers to those best suited to their environment, not necessarily the strongest.

Genetic Drift: A mechanism of evolution that involves random changes in the frequency of alleles in a population, which can impact genetic variation over time.