Natural Selection

  • Natural Selection is a fundamental concept in biology that describes the gradual process by which biological traits become either more or less common in a population. This process is driven by environmental factors and results in the evolution of species.

  • The theory of natural selection was proposed by Charles Darwin during the 19th century. He suggested that ‘survival of the fittest’ was a fundamental law of nature, leading to evolution over time.

  • ‘Survival of the fittest’ refers to individuals within a species who are best adapted to their environment being most likely to survive and reproduce. This, in turn, results in the inheritance of their successful traits in future generations.

  • Variation within species influences natural selection. These differences can be a result of genetic variation (such as mutation or recombination) or environmental factors. For example, some members of a beetle population might be green, while others might be brown. Such variability could affect their survival.

  • Organisms produce more offspring than can survive due to constraints like predation, disease, and food scarcity. This leads to competition for resources - a major driving force for natural selection.

  • Over time, characteristics that enable an organism to survive and reproduce more successfully will become more common in the population. This change in the frequency of characteristics (or traits) in a population over generations is an example of evolution by natural selection.

  • As environments can change, adaptability is vital. If the environment changes, different traits might become more beneficial, leading to different organisms surviving and reproducing - this is also part of the natural selection process.

  • An example of natural selection in action is the development of antibiotic resistance. Bacteria that are resistant to antibiotics survive and reproduce more successfully than non-resistant bacteria when exposed to these drugs.

  • Human activity can also drive natural selection. Examples include selective breeding and the creation of environments in which certain traits are more advantageous, such as pesticide resistance in insects.

  • It’s essential to understand that natural selection does not come with a purpose or forethought. It is a result of random, spontaneous changes that can be beneficial, neutral, or deleterious. Only beneficial ones lead to adaptation due to increased survival and reproduction.

  • An understanding of natural selection leads to improved strategies in conservation, medicine, agriculture, and other fields. It can help predict which species might be at risk from environmental changes or how disease-causing organisms might evolve.

Remember to check past papers, specification details, and practise questions to ensure a thorough understanding of natural selection for your biology study.