The Evolution of PopulationsThe Evolution of Populations

VariationsVariations

Genetic Variations Differences in individuals based on DNA or genes

For example different hair color through DNA differences

Geographic Variations Differences in individuals based on separations

between two groups For example, variations in beak size of birds based on

the resources available in the geographic area

Genetic Variations Differences in individuals based on DNA or genes

For example different hair color through DNA differences

Geographic Variations Differences in individuals based on separations

between two groups For example, variations in beak size of birds based on

the resources available in the geographic area

Population requirementsPopulation requirements

Populations Same species Live in the same area Interbreed producing fertile offspring

Populations are determined by their gene pool - the imaginary “pool” that consists of all copies of every type of allele at every locus

Populations Same species Live in the same area Interbreed producing fertile offspring

Populations are determined by their gene pool - the imaginary “pool” that consists of all copies of every type of allele at every locus

Hardy-Weinberg PrincipleHardy-Weinberg Principle

It makes many assumptions Mating is random No migration in or out of populations No gene flow No mutations No natural selection Infinite population

It makes many assumptions Mating is random No migration in or out of populations No gene flow No mutations No natural selection Infinite population

Hardy-Weinberg MathHardy-Weinberg Math

p = frequency of dominant allele q = frequency of recessive allele p2 = frequency of homozygous dominant alleles q2 = frequency of homozygous recessive alleles 2pq = frequency of heterozygous alleles

p = frequency of dominant allele q = frequency of recessive allele p2 = frequency of homozygous dominant alleles q2 = frequency of homozygous recessive alleles 2pq = frequency of heterozygous alleles

Hardy-Weinberg EquationHardy-Weinberg Equation

p2 + 2pq + q2 = 1

p2 + 2pq + q2 = 1

Expected frequency of homozygous dominant alleles

Expected frequency of heterozygous alleles

Expected frequency of homozygous recessive alleles

Genetic DriftGenetic Drift Genetic Drift is the chance events can cause

allele frequencies to fluctuate unpredictably from generation to generation Founder Effect Bottleneck Effect

Genetic Drift is the chance events can cause allele frequencies to fluctuate unpredictably from generation to generation Founder Effect Bottleneck Effect

Founder EffectFounder Effect A few members of a larger population

become isolated

This group then establishes a new population whose gene pool differs from that of the source

A few members of a larger population become isolated

This group then establishes a new population whose gene pool differs from that of the source

Founder Effect ExampleFounder Effect Example

The Dutch population moving from their homeland of the Netherlands to South Africa, creating a small population In this population today, the rate of Huntington’s

Disease is extremely high This is because a few people out of the small

amount of original settlers had the disease, thus there was a higher chance for people to inherit it than in the large population

Therefore, more people have the disease

The Dutch population moving from their homeland of the Netherlands to South Africa, creating a small population In this population today, the rate of Huntington’s

Disease is extremely high This is because a few people out of the small

amount of original settlers had the disease, thus there was a higher chance for people to inherit it than in the large population

Therefore, more people have the disease

Bottleneck EffectBottleneck Effect

A natural disaster causes a large reduction in population size The surviving population by chance has a

different allele frequency than the large population and thus, the gene pool is changed

A natural disaster causes a large reduction in population size The surviving population by chance has a

different allele frequency than the large population and thus, the gene pool is changed

Bottleneck Effect ExampleBottleneck Effect Example The Northern Elephant Seal was nearly completely

annihilated in the late 19th century through people hunting it for its blubber. Because of this, the Northern Elephant Seal does not have the same variations in the gene pool the Southern Elephant Seals do The Northern Elephant Seals are smaller than the Southern The Northern Elephant Seals have longer trunks

The Northern Elephant Seal was nearly completely annihilated in the late 19th century through people hunting it for its blubber. Because of this, the Northern Elephant Seal does not have the same variations in the gene pool the Southern Elephant Seals do The Northern Elephant Seals are smaller than the Southern The Northern Elephant Seals have longer trunks

Northern

Southern

Early EarthEarly Earth

Described as being a “hot thin soup” Everything lived in the water which was

made of amino acids, lipids, sugars and nitrogenous bases These are theorized to have come from comets

that hit Earth and underwater volcanoes

Described as being a “hot thin soup” Everything lived in the water which was

made of amino acids, lipids, sugars and nitrogenous bases These are theorized to have come from comets

that hit Earth and underwater volcanoes

Earth TimelineEarth Timeline

First prokaryotes (single celled)

First eukaryotes (single celled)

First multi-celled prokaryotes

First land animals and plants

3,500

2,100

1,200

500

Numbers are in millions of years ago

Descent with Modification: Darwinian View of Life

Descent with Modification: Darwinian View of Life

Darwin’s Theory of EvolutionDarwin’s Theory of Evolution

New species evolve from old species Populations undergo genetic changes over time Driven by natural selection Organisms that have a particular trait that allows

them to survive in their environment are more likely to reproduce and pass the trait onto the next generation

Every living organism shares a common ancestor

New species evolve from old species Populations undergo genetic changes over time Driven by natural selection Organisms that have a particular trait that allows

them to survive in their environment are more likely to reproduce and pass the trait onto the next generation

Every living organism shares a common ancestor

Darwin’s Theory of Evolution continued

Darwin’s Theory of Evolution continued

Four requirements for theory to be true More offspring are produced then can survive Must be competition for resources in

environment Must be genetic variation in population Some genetic combinations must give an

advantage in survival

Four requirements for theory to be true More offspring are produced then can survive Must be competition for resources in

environment Must be genetic variation in population Some genetic combinations must give an

advantage in survival

Natural SelectionNatural Selection Darwin believed in “survival of the fittest”

This means that organisms most suited to their environment, not necessarily the strongest, would survive to reproduce

According to Darwin’s theory, success is measured by reproductive accomplishment (having babies)

Darwin believed in “survival of the fittest” This means that organisms most suited to their environment,

not necessarily the strongest, would survive to reproduce

According to Darwin’s theory, success is measured by reproductive accomplishment (having babies)

Two Evolutionary TheoriesTwo Evolutionary Theories

Punctuated Equilibrium - Species stay relatively similar for long periods of time (thousands of years) followed by rapid genetic change, forming new species Thought to be response to dramatic changes in

environment

Punctuated Equilibrium - Species stay relatively similar for long periods of time (thousands of years) followed by rapid genetic change, forming new species Thought to be response to dramatic changes in

environment

Two Evolutionary Theories continued

Two Evolutionary Theories continued

Gradualism - Species change very slowly over time, until they obtain sufficient changes to be called an independent species

Gradualism - Species change very slowly over time, until they obtain sufficient changes to be called an independent species

Two Evolutionary Theories continued

Two Evolutionary Theories continued

Evidence for Natural SelectionEvidence for Natural Selection Fossil Record

Much of the evidence for Natural Selection is found in similarities in fossils

Comparative anatomy Homologous Structures: Come from same embryological tissue

(hands and wings, similar bone structure + DNA similarities) Analogous Structures: Similar purpose, different origin (Bat and

Bee wings, both used to fly but few similarities in DNA) Vestigial Organs

Remnants of features no longer used in an organism (Tailbone in humans, leg stubs in whale, etc)

No other explanation for their presence other then evolution

Fossil Record Much of the evidence for Natural Selection is found in similarities

in fossils Comparative anatomy

Homologous Structures: Come from same embryological tissue (hands and wings, similar bone structure + DNA similarities)

Analogous Structures: Similar purpose, different origin (Bat and Bee wings, both used to fly but few similarities in DNA)

Vestigial Organs Remnants of features no longer used in an organism (Tailbone in

humans, leg stubs in whale, etc) No other explanation for their presence other then evolution

Types of SelectionTypes of Selection

Directional Selection - Selection favors one phenotype and causes a shift toward an extreme

Example - If a certain coloration provides rats with good camouflage to hide from predators, more organisms with that coloration would survive and reproduce

Directional Selection - Selection favors one phenotype and causes a shift toward an extreme

Example - If a certain coloration provides rats with good camouflage to hide from predators, more organisms with that coloration would survive and reproduce

Types of Selection cont.Types of Selection cont.

Stabilizing Selection - Average phenotype is favored, extremes selected against

Example - If the color of the rocks in which rats hide is a dull gray, and the average rat coloration is gray, any differently colored rats will stand out to predators and be less likely to survive

Stabilizing Selection - Average phenotype is favored, extremes selected against

Example - If the color of the rocks in which rats hide is a dull gray, and the average rat coloration is gray, any differently colored rats will stand out to predators and be less likely to survive

Types of Selection cont.Types of Selection cont.

Disruptive Selection - Extremes are favored and average is selected against

Example - If rats hide in light and dark colored rocks, any intermediately colored rats will be easily targeted and the extremes will be more likely to reproduce

Disruptive Selection - Extremes are favored and average is selected against

Example - If rats hide in light and dark colored rocks, any intermediately colored rats will be easily targeted and the extremes will be more likely to reproduce

Species and SpeciationSpecies and Speciation

Species - a group of potentially, breeding natural populations that are reproductively isolated from other groups

Speciation - Emergence of a new species

Species - a group of potentially, breeding natural populations that are reproductively isolated from other groups

Speciation - Emergence of a new species

Phyletic SpeciationPhyletic Speciation

Phyletic Speciation - Slow changes occur over thousands of years until enough changes have been acquired for the new species to be reproductively isolated from the “mother” species Species A -> A1 -> A2->…A20

One would never find Ax living at the same time as species “A”, the original species will turn into the new species

Phyletic Speciation - Slow changes occur over thousands of years until enough changes have been acquired for the new species to be reproductively isolated from the “mother” species Species A -> A1 -> A2->…A20

One would never find Ax living at the same time as species “A”, the original species will turn into the new species

Divergent SpeciationDivergent Speciation

Divergent Speciation - Species will branch off origin species to create new species “Mother” species and offshoot species can exist at the

same time

Wolves gave rise to dogs, but wolves still exist

Divergent Speciation - Species will branch off origin species to create new species “Mother” species and offshoot species can exist at the

same time

Wolves gave rise to dogs, but wolves still exist

Types of Divergent SpeciationTypes of Divergent Speciation

Allopatric speciation - Most common type of Divergent speciation, deals with actually physical separation Geographic Barriers - 2 populations evolve differently Natural disasters - drive populations away to new

environments Adaptive radiation - Spread of population into new environment

with lany new evolutionary adaptations, normally forms many new species

Character displacement - If competition with other species, organisms evolve exaggerated differences between species

Because natural selection favors species that can find unoccupied niche in environment

Allopatric speciation - Most common type of Divergent speciation, deals with actually physical separation Geographic Barriers - 2 populations evolve differently Natural disasters - drive populations away to new

environments Adaptive radiation - Spread of population into new environment

with lany new evolutionary adaptations, normally forms many new species

Character displacement - If competition with other species, organisms evolve exaggerated differences between species

Because natural selection favors species that can find unoccupied niche in environment

Types of Divergent SpeciationTypes of Divergent Speciation

Sympatric speciation - New species forms while still with old species geographically More common with plants Happens most easily with hybridization - mating 2

species Usually doesn’t work because the mismatch of homologous

chromosomes Plants avoid this with polyploidy - Doubles each chromosome

during mitosis -> instant homologous chromosomes

Sympatric speciation - New species forms while still with old species geographically More common with plants Happens most easily with hybridization - mating 2

species Usually doesn’t work because the mismatch of homologous

chromosomes Plants avoid this with polyploidy - Doubles each chromosome

during mitosis -> instant homologous chromosomes

Allopatric vs Divergent Speciation

Allopatric vs Divergent Speciation

Reproductive Isolating Mechanisms

Reproductive Isolating Mechanisms

Prezygotic - Occurs before fertilization Different mating rituals Different mating seasons Different “lock and key”

Prezygotic - Occurs before fertilization Different mating rituals Different mating seasons Different “lock and key”

Mating Ritual VideoMating Ritual Video

http://www.youtube.com/watch?v=ACTwvx_STK4&feature=related

When you finish watching this video do not quit safari, instead just click back to the PowerPoint

http://www.youtube.com/watch?v=ACTwvx_STK4&feature=related

When you finish watching this video do not quit safari, instead just click back to the PowerPoint

Reproductive Isolating Mechanisms

Reproductive Isolating Mechanisms

Postzygotic - Occurs after fertilization Embryo will most likely not survive, or if born

will be weak or infertile, because chromosome mismatch

Mules are examples of infertile survivors

of postzygotic reproductive isolation

Postzygotic - Occurs after fertilization Embryo will most likely not survive, or if born

will be weak or infertile, because chromosome mismatch

Mules are examples of infertile survivors

of postzygotic reproductive isolation

Evolutionary TrendsEvolutionary Trends

Divergent Evolution - Separation of related species Adapt to differences in environments

Divergent Evolution - Separation of related species Adapt to differences in environments

Evolutionary TrendsEvolutionary Trends

Convergent Evolution - Different unrelated species evolve into similar organisms Again, to adapt to environment, (ex. Whales

and Fish) but different

Convergent Evolution - Different unrelated species evolve into similar organisms Again, to adapt to environment, (ex. Whales

and Fish) but different

Evolutionary TrendsEvolutionary Trends

Coevolution - Two species evolve together and affect each other Example: Bees pollinate flowers and spread

their seeds

Coevolution - Two species evolve together and affect each other Example: Bees pollinate flowers and spread

their seeds

Works CitedWorks Cited http://www.turbosquid.com/FullPreview/Index.cfm/ID/255352 DNA picture http://www.zastavki.com/pictures/1024x768/2010/Animals_Birds_Birdies_with_dark_blue_paws_023799_.jpg Blue footed booby picture for populations http://www.cancer.gov/cancertopics/understandingcancer/cancergenomics/page36 founder effect picture http://faculty.fortlewis.edu/dott_c/Bio125-ConsBio/ClassMeetings/Week08-ExtinctVortex/8a-Endangerment.htm picture of bottleneck effect http://www.eleseal.org/bio/north.html slide 11 information http://www.deeproot.com/blog/blog-entries/celebrating-the-earth-on-earth-day/earth-day Earth picture http://www.tutorvista.com/content/biology/biology-iii/origin-life/origin-life-steps.php picture of first prokaryote http://www.aenvirocure.com/DB_DATA/contams/organic/BACTERIA.HTML picture of first unicellular prokaryote http://www.networlddirectory.com/blogs/permalinks/4-2006/gap-between-fish-and-land-animals.html first land animal picture http://images.nationalgeographic.com/wpf/media-live/photos/000/005/cache/grey-wolf_565_600x450.jpg wolf picture http://goldcountryhoney.com/plant-a-garden-that-welcomes-nature%E2%80%99s-insect-pollinators/ bee picture http://seacloud-2.appspot.com/images/baby2.gif Picture of baby http://anthro.palomar.edu/synthetic/images/graph_of_punctuated_equilibrium.gif picture of punctuated equilibrium http://anthro.palomar.edu/synthetic/images/graph_of_phyletic_gradualism.gifPicture of Gradualism http://casarcia.com/life/ch06/6-1not3.jpg Pict of gradualism+PE http://avonapbio.pbworks.com/f/directional_selection.gif Pict of directional selection http://img.sparknotes.com/figures/A/a3aa6bb95c7d70781cc0089d17f9160f/stable.gif Pict of stabalizing selection http://img.sparknotes.com/figures/A/a3aa6bb95c7d70781cc0089d17f9160f/disrupt.gif pic of disruptive selection Theory of Evolution slides- Roisen http://melinabeachturtlehatchery.files.wordpress.com/2010/07/turtle4.jpg turtle picture http://seacloud-2.appspot.com/images/baby2.gif picture of baby http://anthro.palomar.edu/synthetic/images/graph_of_phyletic_gradualism.gif Picture of Gradualism http://a-z-animals.com/media/animals/images/470x370/mule1.jpg Picture of mule http://thisoldearth.net/Images/diverge_evol.gif Picture of divergent evolution Bio textbook – alloptric and divergent speciation picture

http://www.turbosquid.com/FullPreview/Index.cfm/ID/255352 DNA picture http://www.zastavki.com/pictures/1024x768/2010/Animals_Birds_Birdies_with_dark_blue_paws_023799_.jpg Blue footed booby picture for populations http://www.cancer.gov/cancertopics/understandingcancer/cancergenomics/page36 founder effect picture http://faculty.fortlewis.edu/dott_c/Bio125-ConsBio/ClassMeetings/Week08-ExtinctVortex/8a-Endangerment.htm picture of bottleneck effect http://www.eleseal.org/bio/north.html slide 11 information http://www.deeproot.com/blog/blog-entries/celebrating-the-earth-on-earth-day/earth-day Earth picture http://www.tutorvista.com/content/biology/biology-iii/origin-life/origin-life-steps.php picture of first prokaryote http://www.aenvirocure.com/DB_DATA/contams/organic/BACTERIA.HTML picture of first unicellular prokaryote http://www.networlddirectory.com/blogs/permalinks/4-2006/gap-between-fish-and-land-animals.html first land animal picture http://images.nationalgeographic.com/wpf/media-live/photos/000/005/cache/grey-wolf_565_600x450.jpg wolf picture http://goldcountryhoney.com/plant-a-garden-that-welcomes-nature%E2%80%99s-insect-pollinators/ bee picture http://seacloud-2.appspot.com/images/baby2.gif Picture of baby http://anthro.palomar.edu/synthetic/images/graph_of_punctuated_equilibrium.gif picture of punctuated equilibrium http://anthro.palomar.edu/synthetic/images/graph_of_phyletic_gradualism.gifPicture of Gradualism http://casarcia.com/life/ch06/6-1not3.jpg Pict of gradualism+PE http://avonapbio.pbworks.com/f/directional_selection.gif Pict of directional selection http://img.sparknotes.com/figures/A/a3aa6bb95c7d70781cc0089d17f9160f/stable.gif Pict of stabalizing selection http://img.sparknotes.com/figures/A/a3aa6bb95c7d70781cc0089d17f9160f/disrupt.gif pic of disruptive selection Theory of Evolution slides- Roisen http://melinabeachturtlehatchery.files.wordpress.com/2010/07/turtle4.jpg turtle picture http://seacloud-2.appspot.com/images/baby2.gif picture of baby http://anthro.palomar.edu/synthetic/images/graph_of_phyletic_gradualism.gif Picture of Gradualism http://a-z-animals.com/media/animals/images/470x370/mule1.jpg Picture of mule http://thisoldearth.net/Images/diverge_evol.gif Picture of divergent evolution Bio textbook – alloptric and divergent speciation picture