Natural Selection

Definition

Natural selection is the process by which organisms that are better adapted to their environment tend to survive and reproduce more successfully than others. This mechanism of evolution explains how species change over time, leading to adaptations that enhance survival in specific habitats. It emphasizes variation among individuals, competition for resources, and the role of environmental pressures in shaping the evolutionary trajectory of organisms.

5 Must Know Facts For Your Next Test

1. Natural selection was first articulated by Charles Darwin in the 19th century as a key mechanism of evolution.
2. This process relies on genetic variation within populations, which provides the raw material for evolutionary change.
3. Natural selection acts on phenotypes, or observable traits, rather than directly on genotypes or genetic makeup.
4. Environmental factors such as climate, food availability, and predators can significantly influence which traits are favored through natural selection.
5. Over time, natural selection can lead to speciation, where populations evolve into distinct species due to accumulated adaptations.

Review Questions

• How does natural selection contribute to the evolutionary changes observed in human evolution?
  • Natural selection plays a crucial role in human evolution by favoring traits that enhance survival and reproductive success in changing environments. For instance, adaptations such as bipedalism and increased brain size provided early humans with advantages in locomotion and problem-solving. Over generations, these beneficial traits became more common in the population, demonstrating how natural selection shapes human development in response to environmental pressures.
• Discuss the impact of natural selection on the evolution of fish species in aquatic environments.
  • Natural selection profoundly impacts fish evolution by favoring adaptations that improve survival in specific aquatic environments. For example, variations in body shape and coloration can influence predation risk and mating success. Fish that possess traits allowing them to better exploit available resources or evade predators tend to reproduce more successfully, leading to a gradual change in population characteristics over time. This process contributes to the incredible diversity of fish species found in different ecosystems.
• Evaluate the role of natural selection in the evolutionary changes observed in bird species, particularly regarding their adaptations for flight.
  • Natural selection has been instrumental in shaping bird species through adaptations related to flight. Birds with lighter bones, specialized wing structures, and feathers have better chances of surviving and reproducing as they are more efficient fliers. The variation in beak shape and size among different bird species also reflects adaptations that have arisen through natural selection based on available food sources. By analyzing these traits, we can understand how specific environmental pressures have driven evolutionary changes in birds over millions of years.

Related terms

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

Genetic Variation: The diversity in gene frequencies among individuals within a population, which is essential for natural selection to occur.

Survival of the Fittest: A phrase often used to describe natural selection, referring to the idea that individuals with advantageous traits are more likely to survive and reproduce.