Table of Contents
Examples of Natural Selection
i. Darwin's Finches
Darwin’s finches are a great illustration of how species’ gene pools have evolved to ensure long-term survival of their progeny. The figure below depicts how Darwin’s Finches have evolved to take advantage of diverse ecological niches for feeding. Their beaks have developed over time to be the most functional for them.
Finches that consume grubs, for example, have a narrow extended beak that they use to dig into holes in the ground and retrieve the grubs. Finches that consume buds and fruit would have a harder time doing so, but their claw-like beaks can crush down their food, giving them a selective advantage in situations where buds are the only true food supply.
Darwin made observations while charting the Galapagos Islands that would eventually give rise to his theory of evolution.
ii. Industrial Melanism
Polymorphism is the occurrence of two separate groups of species that are both members of the same species. Natural selection governs the evolution of these creatures’ alleles through time, and genetic differences between groups in various settings emerge quickly, as in the case of industrial melanism.
Industrial melanism affects a moth species known as the peppered moth, and it has become increasingly common since the beginning of the industrial age. In terms of industrial melanism, the following argument elaborates on the concepts involved in natural selection.
1. Pollution, which has been increasingly prevalent in today’s society since the industrial revolution, alters the environment, notably in the 1800s when soot from chimneys and factories accumulated on the sides of buildings, turning them a deeper hue.
2. As a result, the peppered moth, which had a light look, stood out more against the darker backdrops of sooty structures.
3. Because they are more noticeable against a dark backdrop, predators of the peppered moth were able to discover them more quickly.
4. Mutations resulted in the emergence of a new peppered moth strain with a darker phenotypic than the white peppered moth.
5. This meant that in areas where industry had taken its toll, these new, darker peppered moths were once again more difficult to hunt down for their prey.
6. In this case, natural selection would prefer darker moths in polluted settings and whiter moths in less polluted areas due to their ability to blend in with their surroundings and reduce their vulnerability to predators.
iii. Sickle Cell Trait
Consider this natural selection argument in the instance of sickle cell trait, a prevalent genetic abnormality in Africa.
1. Sickle cell trait is a condition that arises when a recessive gene coding for haemoglobin, a component in the blood that transports gases such as oxygen, is present. The allele is either moderately exhibited recessively (sickle cell anaemia) or entirely expressed recessively (full-blown anaemia). No sickle cell trait is expressed in the phenotypic if this specific allele is dominant.
2. In the case of a recessive gene, the foregoing events result in structural abnormalities in red blood cells, significantly limiting the organism’s ability to absorb oxygen.
3. It was mentioned that this mutation occurs often in Africa, where malaria cases are common.
4. A proven relationship was established, stating that those with sickle cell trait or anaemia are immune to malaria’s effects.
5. This is another another example of natural selection at action. Although sickle cell trait or anaemia are not favourable traits in and of themselves, they are beneficial in locations where malaria poses a larger danger to genome preservation (i.e. surviving).
6. Either way, the partial dominance of this genetic expression is advantageous.
Examples of Natural Selection FAQ
Since Darwin’s initial investigations, scientists have viewed natural selection in this light. Humans deliberately breed species in the twenty-first century to create hybrid species with the best DNA of both parents, a process known as selective breeding. Adaptive radiation is the evolution of multiple new species from a recent ancestral source, each suited to use or occupy an empty adaptive zone.
Examples of Natural Selection Citations
- Natural selection in mimicry. Biol Rev Camb Philos Soc . 2020 Apr;95(2):291-304.
- Natural selection. VII. History and interpretation of kin selection theory. J Evol Biol . 2013 Jun;26(6):1151-84.