Natural selection

Definition

Natural selection is the process by which certain traits increase in frequency within a population due to the advantages they confer for survival and reproduction. This mechanism is fundamental to evolution, as it explains how species adapt to their environments over time, with those best suited for their habitats being more likely to survive and reproduce.

5 Must Know Facts For Your Next Test

1. Natural selection operates on existing genetic variation within a population; it does not create new traits but favors those that provide survival advantages.
2. The concept of natural selection was first formulated by Charles Darwin and is often summarized by the phrase 'survival of the fittest.'
3. Natural selection can lead to speciation, where populations diverge into new species when they adapt to different environmental pressures.
4. Environmental changes can shift the dynamics of natural selection, potentially making previously advantageous traits less beneficial or even harmful.
5. Evidence of natural selection can be observed through phenomena such as antibiotic resistance in bacteria and changes in beak size among finches in response to food availability.

Review Questions

• How does natural selection contribute to the process of adaptation in populations over time?
  • Natural selection drives adaptation 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 as it becomes better suited for its surroundings. This ongoing process results in a population that is increasingly adapted to its ecological niche.
• Discuss the role of genetic variation in the mechanism of natural selection and its importance for evolution.
  • Genetic variation is crucial for natural selection because it provides the raw material on which selection acts. Without variation, all individuals would be identical, and there would be no differences for natural selection to favor or eliminate. Genetic diversity allows populations to adapt to changing environments; as some individuals carry beneficial mutations, they are more likely to survive and reproduce, passing those traits on to future generations, thus driving evolutionary change.
• Evaluate the impact of environmental changes on the dynamics of natural selection and its implications for biodiversity.
  • Environmental changes can significantly influence natural selection by altering which traits are advantageous for survival. For instance, climate change may shift habitats, impacting food availability or introducing new predators. This can lead to a decrease in certain species while allowing others to thrive, potentially causing shifts in biodiversity. Such dynamics emphasize the importance of adaptability and resilience within ecosystems, as species must continually respond to evolving conditions or face extinction.

Related terms

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

Genetic Variation: Differences in DNA sequences among individuals within a population that contribute to diversity in traits and can influence evolutionary outcomes.

Fitness: A measure of an organism's ability to survive and reproduce in its environment, often determined by the presence of advantageous traits.