9B Selection pressures

Question 1

Natural Selection

Answer 1

1. Individuals in a population vary genetically, which leads to phenotypic differences
2. An environmental selection pressures impacts the survivability of organisms within a population and their ability to reproduce
3. Individuals with phenotypes that are fitter or more advantageous under the environmental seleection pressures are conferred a selective advantage, allowing them to survive and reproduce successfully
4. The advantageos tait must be heritable, allowing it to be passd on from the parents to their offspring. Therefore, over time, the frequency of the advantageous allele will increase

Question 2

Sexual selection

Answer 2

A form of natural selection in which the selection pressures is the ability to obtain a mate

Question 3

What are the three graphs of natural selection effect

Answer 3

Stabilising selection - Natural selection select the advantageous population within the most abundant number of individuals within an existing population
Directional Selection - Natural selects smaller number of individuals with the advantageous phenotype resulting in a directional selection to that particular allele.
Disruptive Selection - Natural selections selects the least abundant phenotypes as advantageous which causes the most abundant phenotypes to undergo natural selection

Question 4

The elements of natural selection (3)

Answer 4

1. Decreases genetic diversity as t acts as an opposition to mutation by only selecting the fittest phenotypes within a genetic population
2. Natural selections does not always end up in speciation concepts of natural selection are (Bottleneck effect, Genetic drift, Founder effect)
3. Natural selection relies on th heritability of the advantageous allel and the presence of variation with the exisiting population