Natural selection

Definition

Natural selection is a process in evolutionary biology where organisms better adapted to their environment tend to survive and reproduce more than those less suited. This mechanism drives the evolution of species by favoring advantageous traits, leading to changes in genetic makeup over generations and influencing population dynamics.

5 Must Know Facts For Your Next Test

1. Natural selection operates on existing variations within a population, meaning that it cannot create new traits but rather selects from those that are already present.
2. The concept of natural selection was independently proposed by Charles Darwin and Alfred Russel Wallace in the 19th century, revolutionizing our understanding of evolution.
3. Survival of the fittest does not necessarily mean the strongest; it refers to the reproductive success of individuals with favorable traits.
4. Natural selection can lead to speciation, where populations evolve into distinct species due to selective pressures in different environments.
5. Factors such as environmental changes, competition for resources, and predator-prey relationships play significant roles in shaping the natural selection process.

Review Questions

• How does natural selection contribute to the evolution of a species?
  • Natural selection contributes to evolution by favoring individuals with traits that enhance their survival and reproductive success in a given environment. Over generations, these advantageous traits become more common within the population, leading to gradual changes in the species' genetic makeup. This process allows species to adapt over time, ensuring their survival in changing environments.
• Discuss the role of genetic variation in natural selection and its importance for population dynamics.
  • Genetic variation is crucial for natural selection because it provides the raw material upon which selective pressures act. Without variation, all individuals would be genetically identical, and there would be no traits for natural selection to favor or disfavor. This variation helps populations respond dynamically to environmental changes, as some individuals may possess traits that allow them to thrive under new conditions while others may not.
• Evaluate the impact of environmental factors on the process of natural selection and provide examples.
  • Environmental factors significantly influence natural selection by determining which traits are advantageous in a given context. For instance, in a changing climate where temperatures rise, animals with traits for better heat tolerance may have higher survival rates. Similarly, in an area where certain food sources become scarce, individuals with adaptations for alternative diets may thrive. These examples illustrate how natural selection is not a static process but one that continually shapes populations based on their interactions with the environment.

Related terms

genetic drift: A random process that can lead to changes in the frequency of alleles in a population, independent of natural selection.

mutation: A change in the DNA sequence of an organism's genome that can introduce new traits and contribute to genetic variation.

adaptation: The process by which a species becomes better suited to its environment through the accumulation of advantageous traits over time.