Bell RingerBell Ringer for 5/23 for 5/23

► I need 2 volunteers to pass back I need 2 volunteers to pass back papers…papers…

►Everyone else, take out paper/notebook Everyone else, take out paper/notebook for notes and your Ch. 15.2 vocabfor notes and your Ch. 15.2 vocab

►Answer the following in your notes for Answer the following in your notes for today:today: What are three types of evidence we have What are three types of evidence we have

for the evolution of living organisms?for the evolution of living organisms?

Today’s agendaToday’s agenda

► Discuss 15.1 and review worksheetsDiscuss 15.1 and review worksheets► Lecture on 15.2Lecture on 15.2

Fossil Fossil EvidenceEvidence

► Though the fossil record is incomplete, it Though the fossil record is incomplete, it gives paleontologists a look into the gives paleontologists a look into the structure of ancient organisms.structure of ancient organisms.

► By comparing the anatomical (and in rare By comparing the anatomical (and in rare cases biochemical) evidence to modern day cases biochemical) evidence to modern day organisms, they can fill in the gaps of how organisms, they can fill in the gaps of how life has evolved over time.life has evolved over time.

Anatomical EvidenceAnatomical Evidence What type of structures is this picture What type of structures is this picture

showing?showing?

Homologous structures

These structures are formed in similar ways during embryonic development and share similar ____________; however, they have somewhat different forms and __________________.

origins functio

ns

Anatomical Evidence cont.Anatomical Evidence cont. What type of structures is this picture What type of structures is this picture

showing?showing?

Analogous structures

Some unrelated animals have organs with similar _____________, yet are very different in form and _____________. These organs are analogous.

functionorigin

Anatomical Evidence cont.Anatomical Evidence cont. What type of structures is this picture What type of structures is this picture

showing?showing?

Vestigial structures

Organs or structures that have lost their ________ in modern organisms and have become reduced in size are called vestigial structures.

function

Analysis and interpretationAnalysis and interpretation1.1. The homologous structures in Part 1 are evidence The homologous structures in Part 1 are evidence

of evo. relationships due to each organism having of evo. relationships due to each organism having the same bones present in structures that carry the same bones present in structures that carry out similar functions.out similar functions.

2.2. The is no recent evolutionary relationship between The is no recent evolutionary relationship between a fish fin and the flipper of a whale. While both a fish fin and the flipper of a whale. While both have a similar function, there is no evidence of have a similar function, there is no evidence of internal structures being related.internal structures being related.

3. Hip bones on a whale – as whales live their entire 3. Hip bones on a whale – as whales live their entire lives in the water, they no longer need hip bones lives in the water, they no longer need hip bones to support legs to walk on land.to support legs to walk on land.

Eyes in cave fish – as it is always dark, there is no Eyes in cave fish – as it is always dark, there is no light for their eyes to use to help guide them/find light for their eyes to use to help guide them/find food/etc, so they are unnecessary.food/etc, so they are unnecessary.

Biochemical (DNA) Evidence for Biochemical (DNA) Evidence for EvolutionEvolution

► What you should have noticed:What you should have noticed: In looking at the 2 different proteins (hemoglobin In looking at the 2 different proteins (hemoglobin

on the front, cytochrome c on the back), humans on the front, cytochrome c on the back), humans have the least # of differences with chimps and have the least # of differences with chimps and Rhesus monkeys.Rhesus monkeys.

Shows a close evolutionary relationship.Shows a close evolutionary relationship.► If the amino acid of an organism are similar, the If the amino acid of an organism are similar, the

DNA must also be similar because…DNA must also be similar because… Amino acids are made up of __________.Amino acids are made up of __________. Codons are made up of __________.Codons are made up of __________. mRna is made from ___________.mRna is made from ___________.

codons

3 mRNA basesDNA

Can Can II evolve?evolve?

Write these down!

► Only Only populationspopulations, NOT , NOT individuals, can evolve.individuals, can evolve.

Date: 5/23Date: 5/23

Topic: Chapter 15.2 – Mechanisms of Topic: Chapter 15.2 – Mechanisms of EvolutionEvolution

How does a How does a population population evolve?evolve?

► The The allelic frequencyallelic frequency of a of a stable, non-evolving pop. is stable, non-evolving pop. is unchanging. (it is in unchanging. (it is in genetic genetic equilibriumequilibrium))

► If there is a change in the If there is a change in the allelic freq., the pop is allelic freq., the pop is evolvingevolving

► Hanging around Hanging around the gene pool…the gene pool…

What causes What causes changes in changes in the freq of the freq of alleles?alleles?

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► MutationsMutations in individuals that in individuals that can be passed down to can be passed down to offspring.offspring.

► Genetic driftGenetic drift can greatly affect can greatly affect small pops. small pops. either brings, or takes away, either brings, or takes away,

genes from a popgenes from a pop’’s gene pools gene pool

Topic: Chapter 15.2 – Mechanisms of Topic: Chapter 15.2 – Mechanisms of EvolutionEvolution

Where does Where does natural natural selection fit selection fit in?in?

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► It tests It tests ‘‘newnew’’ genes or alleles genes or alleles to see how well they will to see how well they will survive.survive.

► Allelic freq.Allelic freq.’’s of a pop. s of a pop. change over generations change over generations duedue to the natural selection of to the natural selection of those variations.those variations.

VIDEOVIDEO► 3 patterns/types of natural 3 patterns/types of natural

selectionselection

Topic: Chapter 15.2 – Mechanisms of Topic: Chapter 15.2 – Mechanisms of EvolutionEvolution

StabilizingStabilizing

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Topic: Chapter 15.2 – Mechanisms of Topic: Chapter 15.2 – Mechanisms of EvolutionEvolution

► Favors Favors average average individualsindividuals

► Reduces Reduces variation in variation in pop.pop.

DirectionalDirectional DisruptiveDisruptive► Favors 1 of Favors 1 of

the extreme the extreme variationsvariations

► Leads to Leads to rapid rapid evolution of evolution of a pop.a pop.

► Favors both Favors both of the of the extreme extreme individualsindividuals

► Leads to the Leads to the formation of formation of 2 new species 2 new species in a pop.in a pop.

Which type of natural Which type of natural selection?selection?

Average skin color over time for the human species

Shell colors

Video on peppered moths.

Initially peppered moths were light, over time they became dark.

How do new How do new species species come to be?come to be?

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► Members of similar pops can no Members of similar pops can no longer mate to produce longer mate to produce fertile fertile offspring = new speciesoffspring = new species

► Physical barriersPhysical barriers Geographic isolationGeographic isolation VIDEOVIDEO

► Reproductive isolationReproductive isolation Genetic material is too different Genetic material is too different Different mating behaviors/seasonsDifferent mating behaviors/seasons

► Change in chromosome #sChange in chromosome #s polyploidypolyploidy

Topic: Chapter 15.2 – Mechanisms of Topic: Chapter 15.2 – Mechanisms of EvolutionEvolution

What can What can cause the cause the pops to be pops to be so diff?so diff?

But ligers and tigons exist, they But ligers and tigons exist, they mustmust be a species…right?!?! be a species…right?!?!

► Nope!!Nope!!► In order for an animal In order for an animal

to be considered a to be considered a separate species, it separate species, it needs to be able to needs to be able to produce offspring that produce offspring that can give birth.can give birth.

► Ligers, tigons…and Ligers, tigons…and mules, zorses, and mules, zorses, and beefalos…are all beefalos…are all unable to make unable to make babies!babies!

Convergent Convergent vsvs

DivergentDivergent

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► Convergent evolutionConvergent evolution 2 distantly related organisms 2 distantly related organisms

evolve similar traits evolve similar traits Like meeting someone fr. ½ way Like meeting someone fr. ½ way

around the world and finding out around the world and finding out you are exactly alike.you are exactly alike.

► Divergent evolutionDivergent evolution Species that were similar, evolve Species that were similar, evolve

apartapart Like you and your best childhood Like you and your best childhood

friend becoming 2 very diff. friend becoming 2 very diff. people.people.

VIDEOVIDEO

Topic: Chapter 15.2 – Mechanisms of Topic: Chapter 15.2 – Mechanisms of EvolutionEvolution