NATURAL SELECTION Involves the environment selecting
for/against certain phenotypes
Slide 3
NATURAL SELECTION Involves the environment selecting
for/against certain phenotypes These better adapted phenotypes
survive and leave more offspring carrying the better allele.
Slide 4
NATURAL SELECTION Involves 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).
Slide 5
NATURAL SELECTION Involves 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.
Slide 6
NATURAL SELECTION Involves 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.
Slide 7
NATURAL SELECTION Involves 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.
Slide 8
GENETIC DRIFT Involves the loss, decrease, or increase of an
allele in a small population by chance alone.
Slide 9
GENETIC DRIFT Involves 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.
Slide 10
GENETIC DRIFT Involves 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)
Slide 11
GENETIC DRIFT Involves 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
Slide 12
GENETIC DRIFT Involves 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
)
Slide 13
GENETIC DRIFT Involves 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.
Slide 14
GENETIC DRIFT Involves 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.
Slide 15
THE FOUNDER EFFECT If 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.
Slide 16
THE FOUNDER EFFECT If 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.
Slide 17
THE FOUNDER EFFECT If 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.
Slide 18
THE FOUNDER EFFECT If 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.
Slide 19
BOTTLENECK EFFECT Disasters can reduce a population to a few
survivors.
Slide 20
BOTTLENECK EFFECT Disasters can reduce a population to a few
survivors. Deaths are often random so the survivors are not
representative of the original gene pool.
Slide 21
BOTTLENECK EFFECT Disasters 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.
Slide 22
BOTTLENECK EFFECT Disasters 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
Slide 23
BOTTLENECK EFFECT Disasters 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 EG Chatham
Island robin.
