natural selection

What is natural selection?

Natural selection is a fundamental process in evolution that leads to the adaptation of organisms to their environment over time. It is a mechanism by which certain heritable traits become more or less common in a population based on their effects on an individual's reproductive success. In other words, individuals with advantageous traits are more likely to survive and reproduce, passing those traits on to future generations.

How does natural selection work?

Natural selection operates through four main principles: variation, inheritance, selection, and time.

  1. Variation: Within a population, there is genetic variation due to random mutations and genetic recombination during reproduction. This variation results in individuals having different traits.

  2. Inheritance: Individuals pass on their genetic information to their offspring through reproduction.

  3. Selection: The environment acts as a selective pressure, favoring certain traits that increase an individual's chances of survival and reproduction. These advantageous traits are more likely to be passed on to the next generation.

  4. Time: Over generations, the frequency of advantageous traits increases in the population as they are favored by natural selection.

Examples of natural selection

There are numerous examples of natural selection observed in nature:

  1. Peppered Moths: During the Industrial Revolution in England, pollution caused trees to become covered in dark soot. Previously, light-colored peppered moths were well-camouflaged against tree bark and had higher survival rates than dark-colored moths. However, as trees became darker due to pollution, dark-colored moths had increased survival rates since they were now better camouflaged against the soot-covered trees.

  2. Antibiotic Resistance: Bacteria can evolve resistance to antibiotics through natural selection. When exposed to antibiotics, most bacteria die; however, some may have genetic variations that make them resistant to the drug. These resistant bacteria survive and reproduce, passing on their resistance genes to future generations, leading to the emergence of antibiotic-resistant strains.

  3. Darwin's Finches: The Galapagos Islands are home to a group of finches with different beak shapes and sizes. Each type of beak is adapted for a specific food source available on different islands. Over time, natural selection favored finches with beaks suited for the available food, leading to the diversification of beak shapes among the finch species.