[[Unit 3 (TBD)]]
Evolution is change in the population, not individuals. When changes in allele frequency occur, ==microevolution== has occurred, which is the smallest scale of evolution. Microevolution can eventually lead to ==macroevolution==, which is the creation of new species.

Example begin:

In the Richmond Hill High School forest there lives a population of bunnies.
Let B rep the allele for brown.
Let b rep the allele for white.
How many B? 3B/total 8 alleles
How many b? 5b/total 8 alleles.
Allele frequency of B is 0.375=p (represents allele frequency of dominant trait).
Allele frequency for b is 0.625=q (represents allele frequency of recessive trait).

| Generation       | B   | p           | b   | q           |
| ---------------- | --- | ----------- | --- | ----------- |
| 1-baseline       | 14  | 14/44=0.318 | 30  | 30/44=0.682 |
| 2                | 11  | 11/44=0.25  | 33  | 33/44=0.75  |
| 3                | 16  | 16/44=0.364 | 28  | 28/44=0.636 |
| 4                | 15  | 15/44=0.341 | 29  | 29/44=0.659 |
| 5                | 15  | 15/44=0.341 | 29  | 29/44=0.659 |
| 6-climate change | 2   | 2/44=0.046  | 42  | 42/44=0.954 |

![[Pasted image 20261110105109.png]]

Microevolution has occured because allele frequency changed.
From 0.318 to 0.409.
Natural selection.

To check if a change is significant, use chi square.

Example concluded.

Hardy-Weinberg equation.
If allele frequencies aren't changing, then the population is in ==Hardy-Weinberg== equilibrium (microevolution not occurring).
If allele frequencies change, then microevolution occurs, which can be due to:
* Natural selection.
* Genetic drift.
* Gene flow.
* Mutation.
* Non random mating.

For Hardy-Weinberg equilibrium to occur, these conditions need to be met:
* No mutation, no alleles can arise.
* No migration, no new members and alleles can join/leave.
* Large gene pool.
* Random mating.
* No selection, natural selection doesn't favor one phenotype over the other.
These 5 five things keep the population stable.

==Allele fixation== is when only one allele is present for a particular gene, allele frequency for one allele is 100%. It occurs more often in smaller populations.

![[Pasted image 20261110110316.png]]
Graph one represents Hardy Weinberg Equilibrium, graph 2 represents microevolution and graph 3 represents allele fixation.

$$p+q=1\\p^2+2pq+q^2=1$$  $p^2$ represents genotype frequency (homozygous dominant) while $q^2$ represents genotype frequency for homozygous recessive. $2pq$ represents genotype frequency of heterozygous.

Example 1: 
Black dominant white recessive, 263 black geese 413 white geese.

"what is genotypic frequency of the white geese"
Let B rep black feather.
Let b rep white feather.
bb=$q^2$=413/676=0.6109
"what is allele frequency of white allele"
b=$q^2$=$\sqrt{0.6109}$
=0.7816
"what is alele frequency of black allele"
1-0.7816=0.2184
"genotypic frequencies of homozygous black geese"e
$p^2+2*0.2184*0.7816+0.6109=1$
$p^2=0.0477$
==ALWAYS FIND RECESSIVE ALLELE FREQUENCY FIRST==
"heterozygous genotype frequency"
2pq=2(0.2184)(0.7816)
pq=0.3414

Example concluded.