Natural selection:
Process where certain inherited traits make it easier for some individuals to thrive and reproduce, changing genetic makeup of population over time
Adaptation:
Way in which organisms seem to be ideally shaped to enhance their survival and reproductibility in their environment
Fitness:
Relative ability to survive and create offspring
Principles of natural selection:
1.Different members of a population have various variations
2.Many of these are inheritable
3.Populations can have way more offspring than resources, leading to "The struggle for existence"
4.Favourable traits are more likely to come out on top and spread in a population because more offspring
These lead to change in both phenotype and genotype.
Some types of selection:
Directional selection:
Favoured trait is at one extreme.
Ex:Tall trees made giraffes grow longer necks
Stabilising selection:
Selection against extreme phenotypes.
Ex:Birth weight in humans
Disruptive selection:
Favouring extremes at both extremes, selecting against common traits.
Ex:Peppered moths adopted dark coloration in urban areas and light coloration in rural areas to camoflague themselves
Sexual selection:
Make oneself attractive to the opposite sex or intimidate the same sex for the production of more offspring
Ex:Male peacocks
Artificial selection:
Humans select traits and breed for them in animals/plants
Ex:Crops grown by people