Natural Selection

Definition

Natural selection is the process through which organisms better adapted to their environment tend to survive and produce more offspring. This concept is a key mechanism of evolution, linking genetic variation, adaptation, and the survival of the fittest in the dynamic interplay of species and their environments.

5 Must Know Facts For Your Next Test

1. Natural selection operates on existing variations within populations, favoring traits that enhance survival and reproduction.
2. This process leads to evolutionary change over generations, as advantageous traits become more common in a population.
3. Natural selection can result in speciation, where new species arise when populations adapt to different environments or ecological niches.
4. Environmental factors such as climate, food availability, and predators influence the direction and intensity of natural selection.
5. Natural selection is one of several mechanisms of evolution, along with genetic drift, mutation, and gene flow, which can also shape genetic diversity.

Review Questions

• How does natural selection relate to the concepts of adaptation and fitness in evolutionary biology?
  • Natural selection is fundamentally linked to adaptation and fitness because it is the mechanism through which these concepts operate. Fitness refers to an organism's ability to survive and reproduce in its environment. When individuals possess traits that enhance their fitness—such as better camouflage or resistance to disease—they are more likely to survive and pass those advantageous traits on to their offspring. Over time, this leads to adaptations in populations as beneficial traits become more common due to natural selection.
• Evaluate the significance of natural selection in shaping genetic variation within a population over time.
  • Natural selection plays a crucial role in shaping genetic variation within populations by promoting certain alleles that confer advantages in survival and reproduction. As environmental conditions change, the selective pressures can shift, leading to changes in which traits are favored. This results in a dynamic genetic landscape where alleles that enhance adaptability proliferate while less advantageous ones diminish. Over time, this process contributes significantly to the evolution of populations and their ability to thrive in varying environments.
• Analyze how natural selection interacts with genetic drift and environmental changes during the process of speciation.
  • Natural selection interacts with genetic drift and environmental changes during speciation by influencing which traits are preserved or lost within isolated populations. When populations are separated geographically or ecologically, they experience different selective pressures leading to divergent adaptations. Genetic drift may cause random changes in allele frequencies, particularly in small populations. Together, these factors can result in significant evolutionary divergence, ultimately leading to speciation when reproductive isolation occurs. This interplay demonstrates how natural selection not only drives adaptation but also facilitates the emergence of new species in response to changing environments.

Related terms

Adaptation: The process by which a species becomes better suited to its environment, often resulting from natural selection.

Fitness: A measure of an organism's ability to survive and reproduce in its environment, influencing its contribution to the gene pool of the next generation.

Survival of the Fittest: A phrase often associated with natural selection, it refers to the idea that only those individuals best adapted to their environment will survive and reproduce.