Natural selection

Definition

Natural selection is the process by which organisms that are better adapted to their environment tend to survive and reproduce more than those that are less well adapted. This mechanism leads to the gradual evolution of species over time, influencing genetic diversity and the overall biodiversity of ecosystems. By favoring advantageous traits, natural selection plays a crucial role in shaping species and their interactions within various ecosystems.

5 Must Know Facts For Your Next Test

1. Natural selection operates on existing variations within a population, leading to changes in allele frequencies over generations.
2. This process does not create new traits but selects for traits that already exist, improving the organism's fit to its environment.
3. Natural selection can result in different forms of selection, including stabilizing, directional, and disruptive selection, which shape populations in various ways.
4. The concept of natural selection was independently proposed by Charles Darwin and Alfred Russel Wallace in the mid-19th century.
5. Understanding natural selection is fundamental for conservation efforts as it helps explain how species adapt to changing environments and influences biodiversity.

Review Questions

• How does natural selection contribute to the evolution of species over time?
  • Natural selection contributes to evolution by favoring organisms with traits that enhance their survival and reproductive success. Over time, these advantageous traits become more common in the population, leading to gradual changes in the species. This process not only shapes individual species but also influences the diversity of life forms as they adapt to various environments.
• Compare and contrast natural selection with genetic drift, explaining how each impacts biodiversity.
  • Natural selection is a non-random process that favors individuals with advantageous traits, thereby enhancing adaptation and survival in specific environments. In contrast, genetic drift is a random process that can lead to changes in allele frequencies due to chance events, which may or may not enhance survival. While natural selection tends to increase biodiversity by promoting beneficial adaptations, genetic drift can reduce genetic variation and lead to loss of biodiversity through random fluctuations.
• Evaluate the implications of natural selection on ecosystem diversity and stability.
  • Natural selection has significant implications for ecosystem diversity and stability as it drives the adaptation of species to their environments. By favoring traits that enhance survival, natural selection promotes biodiversity, allowing ecosystems to thrive with a variety of organisms performing different roles. This diversity contributes to ecosystem resilience; diverse ecosystems are often more stable and better able to recover from disturbances compared to less diverse ones, as they possess a wider range of adaptations that can respond to environmental changes.

Related terms

adaptation: A characteristic or trait that enhances an organism's ability to survive and reproduce in its environment.

genetic drift: A random process that can cause changes in allele frequencies in a population, affecting genetic variation independently of natural selection.

speciation: The formation of new and distinct species in the course of evolution, often driven by processes like natural selection.