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AIM: What are the overall factors causing evolution?
Warm-up: Briefly describe 2 mechanisms that could
account for speciation.
5 Agents of evolutionary change
5 Agents of evolutionary changeMutation
5 Agents of evolutionary changeMutation Gene Flow
5 Agents of evolutionary changeMutation Gene Flow Non-random mating
5 Agents of evolutionary changeMutation Gene Flow
Genetic Drift
Non-random mating
5 Agents of evolutionary changeMutation Gene Flow
Genetic Drift Selection
Non-random mating
1. Mutation & Variation
1. Mutation & Variation
1. Mutation & Variation
§Mutation creates variation
1. Mutation & Variation
§Mutation creates variationu new mutations are constantly appearing
1. Mutation & Variation
§Mutation creates variationu new mutations are constantly appearing
§Mutation changes DNA sequence
1. Mutation & Variation
§Mutation creates variationu new mutations are constantly appearing
§Mutation changes DNA sequenceu changes amino acid sequence
1. Mutation & Variation
§Mutation creates variationu new mutations are constantly appearing
§Mutation changes DNA sequenceu changes amino acid sequenceu changes protein
1. Mutation & Variation
§Mutation creates variationu new mutations are constantly appearing
§Mutation changes DNA sequenceu changes amino acid sequenceu changes proteinu changes in protein may
change phenotype & therefore change fitness
2. Gene Flow
2. Gene Flow
2. Gene Flow
§Movement of individuals & alleles in & out of populations
2. Gene Flow
§Movement of individuals & alleles in & out of populationsu seed & pollen distribution by
wind & insect
2. Gene Flow
§Movement of individuals & alleles in & out of populationsu seed & pollen distribution by
wind & insectu migration of animals
2. Gene Flow
§Movement of individuals & alleles in & out of populationsu seed & pollen distribution by
wind & insectu migration of animals§ sub-populations may have
different allele frequencies
2. Gene Flow
§Movement of individuals & alleles in & out of populationsu seed & pollen distribution by
wind & insectu migration of animals§ sub-populations may have
different allele frequencies
§ causes genetic mixing across regions
2. Gene Flow
§Movement of individuals & alleles in & out of populationsu seed & pollen distribution by
wind & insectu migration of animals§ sub-populations may have
different allele frequencies
§ causes genetic mixing across regions
§ reduce differences between populations
Human evolution today§ Gene flow in human
populations is increasing todayu transferring alleles
between populations
Human evolution today§ Gene flow in human
populations is increasing todayu transferring alleles
between populations
Human evolution today§ Gene flow in human
populations is increasing todayu transferring alleles
between populations
Are we moving towards a blended world?
3. Non-random mating
§ Sexual selection
3. Non-random mating
§ Sexual selection
4. Genetic drift
4. Genetic drift
4. Genetic drift
§ Effect of chance events
4. Genetic drift
§ Effect of chance eventsu founder effect
4. Genetic drift
§ Effect of chance eventsu founder effect§ small group splinters off & starts a new colony
Warbler
finch
Tree
finc
hes
Ground finches
4. Genetic drift
§ Effect of chance eventsu founder effect§ small group splinters off & starts a new colony
Warbler
finch
Tree
finc
hes
Ground finches
4. Genetic drift
§ Effect of chance eventsu founder effect§ small group splinters off & starts a new colony
u bottleneck
Warbler
finch
Tree
finc
hes
Ground finches
4. Genetic drift
§ Effect of chance eventsu founder effect§ small group splinters off & starts a new colony
u bottleneck § some factor (disaster) reduces population to
small number & then population recovers & expands again
Warbler
finch
Tree
finc
hes
Ground finches
4. Genetic drift
§ Effect of chance eventsu founder effect§ small group splinters off & starts a new colony
u bottleneck § some factor (disaster) reduces population to
small number & then population recovers & expands again
Founder effect
Founder effect
§When a new population is started by only a few individualsu some rare alleles may be at high
frequency; others may be missing
u skew the gene pool of new population§ human populations that
started from small group of colonists
§ example: colonization of New World
Distribution of blood types§ Distribution of the O type blood allele in native
populations of the world reflects original settlement
Distribution of blood types§ Distribution of the O type blood allele in native
populations of the world reflects original settlement
Distribution of blood types§ Distribution of the O type blood allele in native
populations of the world reflects original settlement
Distribution of blood types§ Distribution of the B type blood allele in native
populations of the world reflects original migration
Distribution of blood types§ Distribution of the B type blood allele in native
populations of the world reflects original migration
Distribution of blood types§ Distribution of the B type blood allele in native
populations of the world reflects original migration
Distribution of blood types§ Distribution of the B type blood allele in native
populations of the world reflects original migration
Bottleneck effect
Bottleneck effect
§When large population is drastically reduced by a disaster
Bottleneck effect
§When large population is drastically reduced by a disasteru famine, natural disaster, loss of habitat…
Bottleneck effect
§When large population is drastically reduced by a disasteru famine, natural disaster, loss of habitat…u loss of variation by chance event
Bottleneck effect
§When large population is drastically reduced by a disasteru famine, natural disaster, loss of habitat…u loss of variation by chance event§ alleles lost from gene pool
Bottleneck effect
§When large population is drastically reduced by a disasteru famine, natural disaster, loss of habitat…u loss of variation by chance event§ alleles lost from gene poolwnot due to fitness
Bottleneck effect
§When large population is drastically reduced by a disasteru famine, natural disaster, loss of habitat…u loss of variation by chance event§ alleles lost from gene poolwnot due to fitness
§ narrows the gene pool
Cheetahs
Cheetahs
§ All cheetahs share a small number of alleles
Cheetahs
§ All cheetahs share a small number of allelesu less than 1% diversity
Cheetahs
§ All cheetahs share a small number of allelesu less than 1% diversityu as if all cheetahs are
identical twins
Cheetahs
§ All cheetahs share a small number of allelesu less than 1% diversityu as if all cheetahs are
identical twins
§ 2 bottlenecks
Cheetahs
§ All cheetahs share a small number of allelesu less than 1% diversityu as if all cheetahs are
identical twins
§ 2 bottlenecksu 10,000 years ago
Cheetahs
§ All cheetahs share a small number of allelesu less than 1% diversityu as if all cheetahs are
identical twins
§ 2 bottlenecksu 10,000 years ago§ Ice Age
Cheetahs
§ All cheetahs share a small number of allelesu less than 1% diversityu as if all cheetahs are
identical twins
§ 2 bottlenecksu 10,000 years ago§ Ice Age
u last 100 years
Cheetahs
§ All cheetahs share a small number of allelesu less than 1% diversityu as if all cheetahs are
identical twins
§ 2 bottlenecksu 10,000 years ago§ Ice Age
u last 100 years§ poaching & loss of habitat
Conservation issuesPeregrine Falcon
Golden Lion Tamarin
Conservation issues§ Bottlenecking is an important
concept in conservation biology of endangered species
Peregrine Falcon
Golden Lion Tamarin
Conservation issues§ Bottlenecking is an important
concept in conservation biology of endangered speciesu loss of alleles from gene pool
Peregrine Falcon
Golden Lion Tamarin
Conservation issues§ Bottlenecking is an important
concept in conservation biology of endangered speciesu loss of alleles from gene poolu reduces variation
Peregrine Falcon
Golden Lion Tamarin
Conservation issues§ Bottlenecking is an important
concept in conservation biology of endangered speciesu loss of alleles from gene poolu reduces variationu reduces adaptability
Breeding programs must consciously outcross
Peregrine Falcon
Golden Lion Tamarin
5. Natural selection
5. Natural selection
§ Differential survival & reproduction due to changing environmental conditions
5. Natural selection
§ Differential survival & reproduction due to changing environmental conditions
§ climate change
5. Natural selection
§ Differential survival & reproduction due to changing environmental conditions
§ climate change§ food source availability
5. Natural selection
§ Differential survival & reproduction due to changing environmental conditions
§ climate change§ food source availability
§ predators, parasites, diseases
5. Natural selection
§ Differential survival & reproduction due to changing environmental conditions
§ climate change§ food source availability
§ predators, parasites, diseases§ toxins
5. Natural selection
§ Differential survival & reproduction due to changing environmental conditions
§ climate change§ food source availability
§ predators, parasites, diseases§ toxins
u combinations of alleles that provide “fitness” increase in the population
5. Natural selection
§ Differential survival & reproduction due to changing environmental conditions
§ climate change§ food source availability
§ predators, parasites, diseases§ toxins
u combinations of alleles that provide “fitness” increase in the population§ adaptive evolutionary change