Natural and artificial selection

Natural and Artificial Selection

Definition and Principles

  • Natural selection is the process where organisms with favourable traits are more likely to reproduce, therefore passing these traits to their offspring.
  • In natural selection, environmental pressures, like predation, disease, and limited resources, influence an organism’s survival.
  • Organisms possessing traits that enhance survival and reproduction in their environments are more likely to pass on these traits to future generations, leading to evolutionary change.
  • Artificial selection deals with the selective breeding of animals or plants by humans, intending to develop, enhance, or suppress specific traits.

Factors for Natural Selection

  • Three necessary elements for natural selection include variation, inheritance, and differential survival and reproduction.
  • Variation: There must be differences in traits among individuals within a population.
  • Inheritance: These traits must be heritable, meaning they can be passed on to offspring.
  • Differential survival and reproduction: Organisms with advantageous traits must reproduce at a greater rate than those with less favourable traits.

Artificial Selection and Breeding

  • Humans have used artificial selection for centuries in plant and animal breeding to enhance traits of economic, aesthetic, or health importance.
  • Common examples include breeding dogs with specific physical traits and crops with higher yields or disease resistance.
  • However, artificial selection can lead to unintentional consequences, such as increased health problems in pedigree dog breeds due to inbreeding.

Impact of Natural Selection on Populations

  • Over time, natural selection shapes populations, favouring traits that boost survival and reproduction.
  • This may lead to speciation, or the formation of a new species if a population splits and evolves separately.
  • Natural selection may also drive adaptive radiation, an evolutionary process where a species diversifies into several different forms to exploit different environmental niches.

Human Influence on Selection

  • Humans can influence natural selection through activities such as habitat destruction, pollution, and climate change.
  • Overfishing, for example, can lead to changes in fish populations, favouring smaller sizes or earlier maturation rates.
  • Similarly, the use of antibiotics can drive natural selection in bacteria, leading to the rise of antibiotic-resistant strains.

Significance of Selection

  • Both kinds of selection allow for adaptation to changing environments, ensuring the survival of organisms across generations.
  • Understanding these processes is critical in many fields, including conservation biology, medicine, and agriculture.
  • For instance, recognising the risks of overusing antibiotics can aid in controlling antibiotic resistance, and understanding what traits are chosen in breeding can help prevent unintended health issues.