Natural selection

Definition

Natural selection is a process in biology where organisms better adapted to their environment tend to survive and produce more offspring. This mechanism drives evolution, as advantageous traits become more common in a population over generations, shaping the genetic makeup of species in response to environmental pressures.

5 Must Know Facts For Your Next Test

1. Natural selection operates on existing variations within a population, meaning it does not create new traits but rather selects from what is already present.
2. The concept of natural selection was first articulated by Charles Darwin, who observed variations in species during his voyage on the HMS Beagle.
3. In the context of skin pigmentation, natural selection favors melanin production in populations exposed to high UV radiation, protecting against skin damage and promoting reproductive success.
4. As human populations migrated and adapted to different environments, variations in skin pigmentation arose as a response to varying levels of sunlight exposure.
5. Natural selection continues to influence human traits, such as skin color, where individuals with advantageous pigmentation are more likely to thrive and pass on their genes.

Review Questions

• How does natural selection explain the variations in skin pigmentation among different populations?
  • Natural selection explains the variations in skin pigmentation as a response to environmental factors, particularly UV radiation. Populations in areas with high UV exposure developed darker skin due to the protective benefits of melanin against sun damage. Conversely, those in lower UV regions evolved lighter skin, which aids in vitamin D synthesis. This adaptive response highlights how natural selection shapes traits based on environmental conditions.
• Evaluate the role of genetic variation in the process of natural selection as it relates to skin pigmentation.
  • Genetic variation is essential for natural selection because it provides the diversity upon which selection can act. In terms of skin pigmentation, different alleles influence melanin production and thus affect an individual's response to UV radiation. Without genetic variation, there would be no differences for natural selection to favor or disfavor. The presence of varied pigmentation genes allows populations to adapt over generations to their specific environments.
• Analyze how the principles of natural selection might apply to other human traits beyond skin pigmentation.
  • The principles of natural selection can be applied to various human traits, such as resistance to diseases or adaptation to altitude. For example, individuals living in high-altitude regions may develop larger lung capacities or increased hemoglobin levels due to selective pressures from lower oxygen levels. Similarly, populations that have historically faced specific pathogens may exhibit genetic adaptations that confer immunity. This analysis underscores how natural selection continuously shapes human biology across diverse environments.

Related terms

Adaptation: A trait that enhances an organism's ability to survive and reproduce in its environment, often resulting from natural selection.

Genetic variation: Differences in DNA among individuals within a population, which are crucial for natural selection as they provide the raw material for evolutionary change.

Survival of the fittest: A phrase often associated with natural selection, it describes the idea that those individuals best suited to their environment are more likely to survive and reproduce.