Natural Selection

Definition

Natural selection is the process through which organisms that are better adapted to their environment tend to survive and reproduce more than those that are less well adapted. This concept highlights how advantageous traits become more common in a population over generations, leading to adaptation and evolution. It is a fundamental mechanism of evolution that explains the diversity of life on Earth.

5 Must Know Facts For Your Next Test

1. Natural selection operates on existing variation within a population, meaning that traits must be present before selection can occur.
2. The concept of 'survival of the fittest' refers to reproductive success rather than physical survival, emphasizing that fitness is about passing genes to the next generation.
3. Natural selection can lead to speciation when populations become isolated and experience different selective pressures over time.
4. Factors such as environmental changes, competition for resources, and predator-prey relationships can influence which traits are favored by natural selection.
5. Natural selection is one of the key mechanisms of evolutionary change, alongside genetic drift, gene flow, and mutation.

Review Questions

• How does natural selection contribute to adaptation in populations?
  • Natural selection contributes to adaptation by favoring individuals with traits that enhance their survival and reproductive success in a given environment. Over time, these advantageous traits become more common in the population as those individuals reproduce more effectively. This process leads to a population that is better suited to its environment, demonstrating how natural selection drives evolutionary change.
• Discuss the role of genetic variation in natural selection and how it influences evolutionary processes.
  • Genetic variation provides the raw material on which natural selection acts. Without variation in traits among individuals in a population, there would be no differences for natural selection to favor or disfavor. This variation can arise from mutations, gene flow, and sexual reproduction. As certain traits confer advantages under specific environmental conditions, these traits increase in frequency through natural selection, shaping the evolutionary trajectory of the population.
• Evaluate the implications of natural selection on species diversity and the emergence of new species over time.
  • Natural selection has significant implications for species diversity and speciation. By favoring different traits in separate environments or isolated populations, natural selection can drive divergence among species. Over long periods, this process may lead to the emergence of new species as adaptations accumulate and populations become reproductively isolated. The interplay between natural selection and environmental factors ultimately shapes the rich tapestry of biodiversity we see today.

Related terms

Mutation: A change in the DNA sequence of an organism that can lead to new traits, providing raw material for natural selection to act upon.

Fitness: The ability of an organism to survive and reproduce in its environment, often determined by its traits and adaptations.

Adaptation:

A characteristic or trait that enhances the survival and reproductive success of an organism in its specific environment.