Problem SolvingProblem Solving Cheetahs are the world’s fastest land mammal. Cheetahs are the world’s fastest land mammal.

They have the ability to run almost 70 mph in They have the ability to run almost 70 mph in pursuit of prey. All other big cats can only run pursuit of prey. All other big cats can only run about 35 mph over very short distancesabout 35 mph over very short distances Do you think the cheetah’s speed is important to its Do you think the cheetah’s speed is important to its

survival? Why or why not?survival? Why or why not? How do you think a biologist would explain the How do you think a biologist would explain the

cheetah’s speed, based on the fact that their cheetah’s speed, based on the fact that their ancestors (and all other cats) only run 35 mphancestors (and all other cats) only run 35 mph

Remember, you are trying to think of a way that Remember, you are trying to think of a way that all all cheetahs got faster over timecheetahs got faster over time

EvolutionEvolution

MicroevolutionMicroevolution MicroevolutionMicroevolution is the occurrence of small-scale is the occurrence of small-scale

changes in changes in allele frequenciesallele frequencies in a population, in a population, over a few generations. Therefore, species can over a few generations. Therefore, species can still breed.still breed.

These changes may be due to several processes: These changes may be due to several processes: MutationMutation: structural changes: structural changes natural selectionnatural selection//artificial selection:artificial selection: selection of certain selection of certain

allele for favorable characteristicsallele for favorable characteristics gene flow:gene flow: transfer of genes from one generation to transfer of genes from one generation to

nextnext genetic driftgenetic drift: random accumulation of genes in a : random accumulation of genes in a

population; some genes may be removed.population; some genes may be removed. http://www.wadsworthmedia.com/biology/http://www.wadsworthmedia.com/biology/

0495119814_starr/big_picture/ch16_bp.swf 0495119814_starr/big_picture/ch16_bp.swf

l Genetic DriftGenetic Drift

Population Population SelectionSelection

Directional Directional selection:selection:

Stabilizing Stabilizing selection:selection:

Disruptive Disruptive selection:selection:

http://http://bcs.whfreeman.cobcs.whfreeman.com/thelifewire/m/thelifewire/content/content/chp23/2302001.htchp23/2302001.htmlml

Gradualism vs punctuated Gradualism vs punctuated equilibriumequilibrium

GradualismGradualism - evolution proceeds at a - evolution proceeds at a steady pace, without the sudden steady pace, without the sudden development of new species or biological development of new species or biological featuresfeatures

Punctuated equilibriumPunctuated equilibriumspecies will experience little evolutionary species will experience little evolutionary

change for most of their geological historychange for most of their geological historyevolution occurs in localized rare, rapid evolution occurs in localized rare, rapid

events of branching speciation (called events of branching speciation (called cladogenesis)cladogenesis)

CladogenesisCladogenesis - the process by which species - the process by which species split into two distinct species, rather than one split into two distinct species, rather than one species gradually transforming into another species gradually transforming into another

•What caused these ancestral related owls to evolve?

•What is the process called?

SpeciationSpeciation Making of a new Making of a new

species over timespecies over time Sexual dimorphismSexual dimorphism

http://www.pbs.org/http://www.pbs.org/wgbh/evolution/wgbh/evolution/library/05/2/library/05/2/l_052_04.html l_052_04.html

Example:Geographic Example:Geographic isolationisolation

Jean-Baptiste LamarkJean-Baptiste Lamark 3 basic ideas3 basic ideas::

1.1. A change in the environment causes a resulting change A change in the environment causes a resulting change in the org. behaviorin the org. behavior

2.2. The behavior change causes the org. to use or not use The behavior change causes the org. to use or not use various organsvarious organs

3.3. The added use of an organ will cause it to grow & The added use of an organ will cause it to grow & become more complex, the disuse of an organ will become more complex, the disuse of an organ will cause it to atrophy or waste awaycause it to atrophy or waste away

For Example, Lamarck thought that giraffes got longer necks by For Example, Lamarck thought that giraffes got longer necks by stretching to reach food. By using all of the muscles in the neck, stretching to reach food. By using all of the muscles in the neck, their necks got longer. The giraffes would then pass on the extra their necks got longer. The giraffes would then pass on the extra height to their offspring, who would be born just as tall as their height to their offspring, who would be born just as tall as their parents.parents.““Use it or lose it”Use it or lose it”

Charles DarwinCharles Darwin A religious, naturalist who put A religious, naturalist who put

together evidence from his together evidence from his voyage to theorize “voyage to theorize “decent decent with modificationwith modification”. (”. (common common ancestor)ancestor)

He reluctantly published He reluctantly published On the Origin of SpeciesOn the Origin of Species in in 1859 after pressure from A. 1859 after pressure from A. Wallace. Wallace.

MacroevolutionMacroevolution

Darwin’s ideaDarwin’s idea

4 Basic Ideas:4 Basic Ideas:

1.1. There are There are variationsvariations w/in populations of organisms w/in populations of organisms and these variations can be passed to offspringand these variations can be passed to offspring

2.2. Each generation produces more offspring than survive Each generation produces more offspring than survive to adulthood = to adulthood = OverproductionOverproduction

3.3. The organism must The organism must struggle to exist.struggle to exist.4.4. The organism with the favorable characteristics The organism with the favorable characteristics

survive better and reproduce more often, thus survive better and reproduce more often, thus transmitting their traits to the next generation “Survival transmitting their traits to the next generation “Survival of the fittest” = of the fittest” = adaptationadaptation

Evolution by Natural SelectionEvolution by Natural Selection

http://www.teachersdomain.org/resource/tdc02.sci.life.evo.howreally/ http://www.teachersdomain.org/resource/tdc02.sci.life.evo.howreally/

SelectionSelection Artificial Selection:Artificial Selection:

Nature provides Nature provides variation, and humans variation, and humans selected useful selected useful variations.variations.

Example: dog Example: dog breedingbreeding

G. Mendel's work on G. Mendel's work on genetics supported genetics supported Darwin’s ideas.Darwin’s ideas.

Natural Selection:Natural Selection: In nature variations In nature variations

are selected for to are selected for to change the species change the species “fitness”.“fitness”.

Example: giraffe neckExample: giraffe neck

Does nature always select Does nature always select best?best?

Antibiotic resistanceAntibiotic resistance http://nortonbooks.com/college/biology/http://nortonbooks.com/college/biology/

animations/ch17a04.htm animations/ch17a04.htm

Evidence supporting EvolutionEvidence supporting EvolutionFossilFossilBiogeographyBiogeographyAnatomyAnatomyDevelopmentalDevelopmentalBiochemicalBiochemical

Time scaleTime scalehttp://www.johnkyrk.com/evolution.html http://www.johnkyrk.com/evolution.html

Nature of FossilsNature of Fossils A A fossilfossil is a trace of long- is a trace of long-

dead organisms. dead organisms. Fossils are often found in Fossils are often found in

layers of sedimentary layers of sedimentary rock, which is formed rock, which is formed when when sedimentsediment, such as , such as dust, sand, or mud is dust, sand, or mud is deposited by wind and deposited by wind and water.water.

Usually develop from the Usually develop from the hard body parts which are hard body parts which are replaced by minerals over replaced by minerals over timetime

Distribution of FossilsDistribution of Fossils The lowest The lowest stratumstratum, or layer, in a cross section , or layer, in a cross section

of Earth is oldest, while the top stratum is the of Earth is oldest, while the top stratum is the most recent.most recent.

Fossils found within a single stratum are of the Fossils found within a single stratum are of the same approximate age.same approximate age.

Relative ageRelative age of a fossil says that a given fossil of a fossil says that a given fossil is younger or older than another based on what is younger or older than another based on what stratum it is foundstratum it is found

Fossil ActivityFossil Activity Absolute ageAbsolute age could be estimated from could be estimated from

radioactive datingradioactive dating

Radioactive Radioactive datingdating

http://www.teachersdomain.org/resource/http://www.teachersdomain.org/resource/tdc02.sci.life.evo.radiodating/ tdc02.sci.life.evo.radiodating/

The Fossil RecordThe Fossil RecordFossil evidence shows a long history of life Fossil evidence shows a long history of life

on Earth. on Earth. The history of life is one of constant change The history of life is one of constant change

and a tremendous diversity of life-formsand a tremendous diversity of life-formsWe can trace how organisms have changed We can trace how organisms have changed

over time by comparing fossil remains from over time by comparing fossil remains from different erasdifferent eras

Lyell: “Principals of geology”; explained that Lyell: “Principals of geology”; explained that the geological features of the earth occurred the geological features of the earth occurred over long periods of time.over long periods of time.

Transitional fossils:Transitional fossils:

How did all these flightless birds, who are related, end up on different contents?

Biogeography EvidenceBiogeography Evidence Biogeographical: Biogeographical: is the study of the geological is the study of the geological

distribution of fossils and of living organisms.distribution of fossils and of living organisms. A comparison of recently formed fossil types with A comparison of recently formed fossil types with

types of living organisms in the same geographic area types of living organisms in the same geographic area shows that new organisms arise in areas where similar shows that new organisms arise in areas where similar forms already lived.forms already lived.

http://www.exploratorium.edu/origins/antarctica/ideas/http://www.exploratorium.edu/origins/antarctica/ideas/gondwana2.html gondwana2.html

How does Biogeography support evolution?How does Biogeography support evolution?

Anatomical EvidenceAnatomical Evidence Homologous Structures – similar features Homologous Structures – similar features

originated in shared ancestor.originated in shared ancestor. i.e. beaks of birds, forelimbs i.e. beaks of birds, forelimbs

Analogous Structures – same function & look Analogous Structures – same function & look alike, but developed independentlyalike, but developed independently

Vestigial Structures – Useful to ancestors but Vestigial Structures – Useful to ancestors but not to modern organism.not to modern organism. i.e. Whales evolved from land animals (hind legsi.e. Whales evolved from land animals (hind legs

Homologous StructuresHomologous Structures

AnalogousAnalogous Structures Structures

Analogous StructuresAnalogous Structures

VestigialVestigial Structures Structures

Developmental BiologyDevelopmental Biology

Embryology:Embryology: in early stages of life in early stages of life embryos are all similar, suggesting embryos are all similar, suggesting common ancestry. common ancestry.

What do evolutionary scientist think when What do evolutionary scientist think when the embryos all appear similar in early the embryos all appear similar in early development?development?

Biochemical EvidenceBiochemical EvidenceMolecular:Molecular: DNA is more similar than DNA is more similar than

different among most species.different among most species.

Human DNA is 99.9% alikeHuman DNA is 99.9% alikeWhat does that suggest about Humans? What does that suggest about Humans?

Patterns of EvolutionPatterns of EvolutionConvergent EvolutionConvergent Evolution – Look similar, but – Look similar, but

not related at all.not related at all. i.e. Shark & porpoisei.e. Shark & porpoise

Divergent Divergent EvolutionEvolution – 2 or – 2 or more related more related populations or populations or species species become more & become more & more dissimilar more dissimilar (Can result in (Can result in new species)new species) i.e. Galapagos i.e. Galapagos

Finches, dogsFinches, dogs

CoevolutionCoevolution – change of 2 or more – change of 2 or more species in close association w/ each other.species in close association w/ each other.Newts produce a potent nerve toxin that Newts produce a potent nerve toxin that

concentrates in their skin.concentrates in their skin.Garter snakes have evolved resistance to this Garter snakes have evolved resistance to this

toxin.toxin.The relationship between these animals has The relationship between these animals has

resulted in an evolutionary arms race that has resulted in an evolutionary arms race that has driven toxin levels in the newt to extreme driven toxin levels in the newt to extreme levels. levels.

What is a Primate?What is a Primate?A primate is a member of the biological A primate is a member of the biological

order Primates, the group that contains order Primates, the group that contains lemurs, lorisids, galagos, tarsiers, lemurs, lorisids, galagos, tarsiers, monkeys, and apes (including great apes monkeys, and apes (including great apes and humans).and humans).

Primate classification

Mountain gorillaMountain gorillaSpends more time on the ground more Spends more time on the ground more

than any other non-human primatethan any other non-human primateFeet most resemble those of humansFeet most resemble those of humansFound in Uganda and RwandaFound in Uganda and Rwanda

Australopithecus afarensisAustralopithecus afarensis

Australopithecus afarensisAustralopithecus afarensis Lived between 3.9 and 2.9 million years agoLived between 3.9 and 2.9 million years ago ““Lucy” was discovered in 1974Lucy” was discovered in 1974 Bipedal = walks on 2 legsBipedal = walks on 2 legs

Before the discoveries of Before the discoveries of A. afarensisA. afarensis in the 1970s, it in the 1970s, it was widely thought that an increase in brain size was widely thought that an increase in brain size preceded the shift to bipedal locomotion.preceded the shift to bipedal locomotion.

“ “Selam”Selam” 3 year old female 3 year old female A.A. afarensisafarensis discovered in Ethiopia discovered in Ethiopia

20062006

ComparingComparing skullsskulls

LUCY