Natural selection

Definition

Natural selection is the process through which organisms that are better adapted to their environment tend to survive and reproduce more successfully than those that are less well adapted. This mechanism drives evolution by favoring advantageous traits, leading to changes in the genetic composition of populations over time. It is a fundamental concept in understanding how biological networks and systems maintain robustness and adaptiveness in changing environments.

5 Must Know Facts For Your Next Test

1. Natural selection operates on the variation within a population, where individuals with advantageous traits are more likely to survive and reproduce.
2. The concept was first articulated by Charles Darwin in the 19th century and remains a cornerstone of evolutionary biology.
3. Natural selection can lead to speciation, where populations evolve into distinct species due to accumulated changes over time.
4. It acts on phenotypes (observable traits) rather than genotypes (genetic makeup), influencing which traits become more common in subsequent generations.
5. The robustness of biological networks is often a result of natural selection, as systems evolve to be resilient against perturbations and environmental changes.

Review Questions

• How does natural selection contribute to the robustness of biological networks?
  • Natural selection enhances the robustness of biological networks by favoring traits that enable organisms to cope with environmental stressors. As variations arise within a population, those individuals with beneficial adaptations are more likely to survive and reproduce. Over time, this leads to the accumulation of traits that increase the overall resilience of the network, allowing it to maintain function despite changes or disruptions in the environment.
• Discuss the role of genetic variation in the process of natural selection and its implications for evolutionary change.
  • Genetic variation is crucial for natural selection, as it provides the raw material upon which selective pressures act. Without variation, there would be no differences among individuals for natural selection to favor. This variation can arise from mutations, gene flow, or sexual reproduction. Consequently, populations with higher genetic diversity have a greater potential for adaptation and survival as they face changing environments or challenges.
• Evaluate how natural selection can lead to both adaptation and speciation within populations over time.
  • Natural selection drives adaptation by promoting traits that improve survival and reproduction in specific environments. As these traits become prevalent, populations may diverge significantly if they inhabit different ecological niches or face distinct selective pressures. This divergence can eventually lead to speciation, where populations become reproductively isolated and evolve into separate species. Thus, natural selection not only shapes individual fitness but also contributes to the broader patterns of biodiversity observed in nature.

Related terms

Fitness: Fitness refers to an organism's ability to survive, reproduce, and pass its genes to the next generation, often measured by its contribution to the gene pool of future generations.

Adaptation: Adaptation is the process by which a species becomes better suited to its environment through changes in physical characteristics or behaviors over generations.

Genetic Drift: Genetic drift is a mechanism of evolution that involves random changes in the frequency of alleles within a population, which can lead to significant evolutionary changes over time.