Agents that change gene frequencies

Agents that change gene frequenciesNatural SelectionInvolves the environment selecting for/against certain phenotypes

Natural SelectionInvolves the environment selecting for/against certain phenotypes These better adapted phenotypes survive and leave more offspring carrying the better allele.Natural SelectionInvolves the environment selecting for/against certain phenotypes These better adapted phenotypes survive and leave more offspring carrying the better allele.Eg Kea (mountain species of Sth Is) and Kaka (bush species of Nth Is).

Natural SelectionInvolves the environment selecting for/against certain phenotypes These better adapted phenotypes survive and leave more offspring carrying the better allele.Eg Kea (mountain species of Sth Is) and Kaka (bush species of Nth Is). Thought to share common ancestor Keas ancestor would tolerate harsh winters. Those that couldnt, would emigrate or die. Natural SelectionInvolves the environment selecting for/against certain phenotypes These better adapted phenotypes survive and leave more offspring carrying the better allele.Eg Kea (mountain species of Sth Is) and Kaka (bush species of Nth Is). Thought to share common ancestor Keas ancestor would tolerate harsh winters. Those that couldnt, would emigrate or die. The frequency of the cold tolerant allele would increase. Natural SelectionInvolves the environment selecting for/against certain phenotypes These better adapted phenotypes survive and leave more offspring carrying the better allele.Eg Kea (mountain species of Sth Is) and Kaka (bush species of Nth Is). Thought to share common ancestor Keas ancestor would tolerate harsh winters. Those that couldnt, would emigrate or die. The frequency of the cold tolerant allele would increase. With time, temp barriers, and change in behaviour would have separated the ancestral birds so much that they became two different species. Genetic driftInvolves the loss, decrease, or increase of an allele in a small population by chance alone. Genetic driftInvolves the loss, decrease, or increase of an allele in a small population by chance alone. Eg population of just one couple. Both are heterozygous for brown eyes. Genetic driftInvolves the loss, decrease, or increase of an allele in a small population by chance alone. Eg population of just one couple. Both are heterozygous for brown eyes. Bb x Bb (phenotype) B or b (genotype)

Genetic driftInvolves the loss, decrease, or increase of an allele in a small population by chance alone. Eg population of just one couple. Both are heterozygous for brown eyes. Bb x Bb (phenotype) B or b (genotype)The couple have 2 kids. The chances of 1 kid being BB is

Genetic driftInvolves the loss, decrease, or increase of an allele in a small population by chance alone. Eg population of just one couple. Both are heterozygous for brown eyes. Bb x Bb (phenotype) B or b (genotype)The couple have 2 kids. The chances of 1 kid being BB is Chances of both kids being BB is 1/16 ( x )

Genetic driftInvolves the loss, decrease, or increase of an allele in a small population by chance alone. Eg population of just one couple. Both are heterozygous for brown eyes. Bb x Bb (phenotype) B or b (genotype)The couple have 2 kids. The chances of 1 kid being BB is Chances of both kids being BB is 1/16 ( x )Therefore there is a 1/16 change of losing the b allele altogether by chance alone.

Genetic driftInvolves the loss, decrease, or increase of an allele in a small population by chance alone. Eg population of just one couple. Both are heterozygous for brown eyes. Bb x Bb (phenotype) B or b (genotype)The couple have 2 kids. The chances of 1 kid being BB is Chances of both kids being BB is 1/16 ( x )Therefore there is a 1/16 change of losing the b allele altogether by chance alone. The Founder effectIf only a few individuals move into a new area, they may only have a few of the available genes from the gene pool of that species. The Founder effectIf only a few individuals move into a new area, they may only have a few of the available genes from the gene pool of that species. Isolated islands have shown rapid evolution because of this. The Founder effectIf only a few individuals move into a new area, they may only have a few of the available genes from the gene pool of that species. Isolated islands have shown rapid evolution because of this. It is unlikely that the few individuals that colonise a new area will have the allele frequencies of the original population. The Founder effectIf only a few individuals move into a new area, they may only have a few of the available genes from the gene pool of that species. Isolated islands have shown rapid evolution because of this. It is unlikely that the few individuals that colonise a new area will have the allele frequencies of the original population. This new founder population will have the potential to be different so evolution will occur faster due to different gene pools. Bottleneck effectDisasters can reduce a population to a few survivors.

Bottleneck effectDisasters can reduce a population to a few survivors. Deaths are often random so the survivors are not representative of the original gene pool. Bottleneck effectDisasters can reduce a population to a few survivors. Deaths are often random so the survivors are not representative of the original gene pool. Some alleles will be above normal number, and some will be lost altogether.

Bottleneck effectDisasters can reduce a population to a few survivors. Deaths are often random so the survivors are not representative of the original gene pool. Some alleles will be above normal number, and some will be lost altogether. Bottleneck effect reduces genetic variability in the population

Bottleneck effectDisasters can reduce a population to a few survivors. Deaths are often random so the survivors are not representative of the original gene pool. Some alleles will be above normal number, and some will be lost altogether. Bottleneck effect reduces genetic variability in the populationEG Chatham Island robin.