Definition
Directional selection is a mode of natural selection in which one extreme phenotype is favored over others, leading to a shift in the population's phenotypic distribution toward that advantageous trait. This process can result in a change in allele frequencies over time, promoting adaptation to specific environmental conditions.
Summary
Directional selection is a fundamental concept in evolutionary biology that describes how certain traits become more common in a population due to environmental pressures. This process can lead to significant changes in the characteristics of a species over time, as individuals with advantageous traits are more likely to survive and reproduce. For example, the classic case of the peppered moth illustrates how industrial pollution favored darker moths, demonstrating the impact of environmental changes on natural selection. Understanding directional selection is crucial for grasping how species adapt to their environments. It highlights the importance of genetic variation and the role of selective pressures in shaping populations. As environments change, the traits that are favored can shift, leading to ongoing evolution and adaptation in the natural world.
Key Takeaways
Understanding Natural Selection
Natural selection is the process by which organisms better adapted to their environment tend to survive and produce more offspring.
highRole of Phenotypes
Phenotypes are the observable traits of an organism, influenced by genetics and environment, crucial for natural selection.
mediumDirectional Selection Effects
Directional selection can lead to significant changes in a population's traits, often reducing genetic diversity.
highReal-World Examples
Examples like the peppered moth illustrate how environmental changes can drive directional selection.
mediumWhat to Learn Next
Stabilizing Selection
Learning about stabilizing selection will help you understand how average traits are favored in populations, contrasting with directional selection.
intermediateDisruptive Selection
Disruptive selection provides insight into how extreme traits can be favored, leading to the formation of new species.
intermediate