5.1 Natural and Artificial Selection
2026-05-17 13:29
Status: #new
Tags: #evolution #biology
5.1 Natural and Artificial Selection
Defining Selection
Types of Selection
- The environment applies a selective pressure on a population.
Selective Pressure
- Environmental factors that favour specific traits (phenotypes) in certain individuals while being disadvantageous to others
Gene Pool
- The genetic information of a entire population
Allele Frequency
- The number of copies of an allele (versions of a trait) compared to the total number of alleles of a population
Natural Selection
Definition
- The process through which species adapt to their environment leading to changes in traits over generations
- Individuals with more fitness pass advantageous traits to their offspring
- Does not anticipate or expect change in the environment.
- Selective pressures (abiotic and biotic) influence natural selection
- Changes in organisms are purely situational
Biotic Pressures
- Living pressures (ie. predators, parasites, resource competition)
Abiotic Pressures
- Non-living pressures (ie. light, wind, soil, water)
Fitness
- Refers to the lifetime reproductive success of an organism, specifically its contribution to the gene pool by producing offspring that will survive
- More offspring
Fitness Level
- More offspring
Artificial Selection
- Selective Breeding for the most desirable alleles found in the gene pool.
- For example: later generations of species will be unlike their original wild sources.
Selective Breeding
- Selective pressures are exerted by humans on a population in order to improve or modify particularly desirable traits
Monoculture
- Extensive plantings of the same varieties of a species over a large expanse of land
Polyculture
- Spreading out of different species over large expanses of land