Biology – Evolution | e-Consult

The theory of evolution by natural selection, primarily developed by Charles Darwin, proposes that species change over time through a process driven by differential survival and reproduction. The core principle is that individuals within a population exhibit variation in their traits. Some of these variations are heritable, meaning they can be passed on to offspring.

Key components of natural selection include:

• Variation: Individuals within a population show differences in their characteristics (phenotypes). This variation arises from random mutations in DNA.
• Inheritance: Many of these variations are heritable, meaning they can be passed from parents to offspring through genes.
• Differential Survival and Reproduction: Individuals with traits that are better suited to their environment are more likely to survive and reproduce. This is often referred to as 'fitness'.
• Adaptation: Over generations, the frequency of advantageous traits increases in the population, leading to adaptation to the environment.

Changes to gene pools from generation to generation occur through these mechanisms:

• Mutation: Random changes in DNA sequence introduce new alleles into the gene pool.
• Gene Flow: The movement of alleles between populations can alter allele frequencies.
• Genetic Drift: Random fluctuations in allele frequencies, particularly in small populations, can lead to the loss or fixation of alleles.
• Natural Selection: As described above, this directly influences allele frequencies by favoring individuals with advantageous traits.

Over long periods, these changes in allele frequencies can accumulate, leading to significant differences between populations. If populations become reproductively isolated (e.g., by geographical barriers), they can diverge genetically until they become distinct species. This process is known as speciation.