Process of natural selection
Natural selection refers to the process by which a species gives rise to new species that has characteristics that can make them better adapted for survival in a particular environment or it may hinder them.
Key steps in natural selection
The key steps/components of natural selection include:
- Variation - A random mutation may occur that can change a certain organism's characteristics. This the reason that organisms can vary in size and colour.
- Inheritance - These different traits can be passed on to the next generation through genetic information.
- Selection - These different traits can benefit the organism by helping it survive or reproduce (e.g. brighter coloration may increase a male peacock's chance at finding a mate or sharper eyes and claws may help an eagle find food etc.)
- Time - Generation after generation, advantageous traits are passed on to greater and greater numbers of offsprings.
- Adaption - After some time, the trait becomes common in the population which results in that population being better adapted to it's environment.
Example of how natural selection occurs
A common example of natural selection would be The British Peppered Moth's change in color from mainly pale to mainly dark during British's industrial age. This started when parts of Britain became polluted and the smoke killed lichens growing on trees and blackened their bark. Pale colored moths which were well camouflaged before they became conspicuous and were then eaten by birds. The rare dark moths, however, were now well camouflaged in the black background. As birds switched from eating mainly dark moths to mainly pale moths, the most common moth color changed from pale to dark, the moths had evolved to suit their environment. This is a clear and common example of natural selection taking place
Selection pressures
Selection pressures are referred to as environmental factors that contribute to selecting which variations will provide the individual with an increased chance of surviving over the others. This means they contribute to the evolutionary change or extinction. Examples include competition, disease, climate change, pollutants etc. A well known example of selection pressure would be the long legs and neck of the giraffe.