Natural Selection

Definition

Natural selection is a process in evolution where organisms that are better adapted to their environment tend to survive and produce more offspring. This concept explains how species evolve over time through the differential survival and reproduction of individuals based on their traits. It serves as a key mechanism for evolution, linking genetics and environmental pressures to changes in populations across generations.

5 Must Know Facts For Your Next Test

1. Natural selection operates on existing variations within a population, meaning that new traits do not arise because they are needed; rather, advantageous traits already present become more common.
2. The concept was first formulated by Charles Darwin and Alfred Russel Wallace in the 19th century, fundamentally changing our understanding of biological evolution.
3. Natural selection can lead to speciation, where populations evolve into distinct species due to adaptation to different environments or ecological niches.
4. Factors such as environmental changes, competition for resources, and predation pressure can influence which traits are favored by natural selection.
5. Natural selection acts on phenotypes, the observable traits of an organism, which are influenced by genetic factors; this means that it is the expression of genes that determines survival, not the genes themselves.

Review Questions

• How does genetic variation play a role in natural selection?
  • Genetic variation is crucial for natural selection because it provides the diverse traits on which natural selection can act. Without variation, all individuals in a population would be similar, and there would be no advantageous traits to favor. As environmental pressures change, those individuals with beneficial traits are more likely to survive and reproduce, passing those advantageous traits onto the next generation, thereby driving evolution.
• Discuss how natural selection contributes to adaptation in populations over time.
  • Natural selection contributes to adaptation by favoring individuals with traits that enhance their survival and reproductive success in a given environment. Over successive generations, these advantageous traits become more common within the population, leading to gradual changes that improve the population's overall fitness. This process can result in populations becoming better suited to their environments as they adapt to challenges like climate changes or competition for resources.
• Evaluate the implications of natural selection for understanding the molecular basis of evolution.
  • The implications of natural selection for understanding the molecular basis of evolution lie in its ability to connect genetic changes at the molecular level with observable evolutionary outcomes. Natural selection acts on phenotypes shaped by genetic variation, which is rooted in DNA mutations and recombination. As certain genetic variations confer advantages that enhance fitness, they become more prevalent through reproduction. This interplay highlights how molecular mechanisms drive evolutionary processes and how natural selection leads to both short-term adaptations and long-term evolutionary trajectories within populations.

Related terms

Genetic Variation: The diversity in gene frequencies within a population, which is essential for natural selection to act upon as it provides the raw material for evolution.

Adaptation: A characteristic or trait that has evolved over time through natural selection, allowing an organism to better survive and reproduce in its environment.

Survival of the Fittest: A phrase often associated with natural selection, describing the idea that individuals with advantageous traits are more likely to survive and reproduce than those without them.