Natural selection

Definition

Natural selection is the process by which organisms that are better adapted to their environment tend to survive and produce more offspring. This mechanism drives evolution by favoring traits that enhance survival and reproduction, leading to gradual changes in species over generations. It connects to understanding variations in populations, the evidence supporting evolutionary theory, genetic principles, and the emergence of new species.

5 Must Know Facts For Your Next Test

1. Natural selection can lead to the evolution of new species by favoring adaptations that are advantageous in changing environments.
2. The process relies on genetic variation within populations, as these variations provide the raw material for selection.
3. Natural selection is not a conscious choice; it occurs naturally through environmental pressures and competition for resources.
4. This mechanism can result in both positive adaptations and negative traits being selected against, influencing the overall fitness of populations.
5. The concept of natural selection was independently discovered by both Charles Darwin and Alfred Russel Wallace in the 19th century.

Review Questions

• How does natural selection contribute to the evolution of species over time?
  • Natural selection contributes to the evolution of species by favoring individuals with traits that provide a survival advantage in their environment. Over time, these advantageous traits become more common within the population as those individuals reproduce more successfully. This gradual change can lead to the emergence of new species, especially when populations become isolated from one another, allowing differing traits to be selected based on local conditions.
• Discuss the role of genetic variation in natural selection and how it impacts population dynamics.
  • Genetic variation is crucial for natural selection because it provides the diversity necessary for some individuals within a population to possess traits better suited for survival and reproduction. Without variation, all individuals would respond similarly to environmental pressures, limiting adaptation potential. As environmental conditions change, those with advantageous traits are more likely to survive and reproduce, thereby influencing population dynamics by changing allele frequencies within the gene pool over generations.
• Evaluate the interplay between natural selection and speciation, providing examples of how these concepts are connected.
  • The interplay between natural selection and speciation is essential for understanding how new species arise. Natural selection drives speciation by favoring different adaptations in populations that become isolated due to geographic barriers or other factors. For example, if two populations of a species adapt to different environments, they may develop distinct traits over time that lead them down separate evolutionary paths. Eventually, these differences can become significant enough that interbreeding is no longer possible, resulting in the formation of new species. This dynamic illustrates how natural selection shapes biodiversity on Earth.

Related terms

Adaptation: A trait that enhances an organism's ability to survive and reproduce in a specific environment.

Gene Pool: The total collection of genes and their variants in a population, influencing the genetic diversity available for natural selection.

Fitness: A measure of an organism's ability to survive and reproduce, relative to other organisms in a population.