Do Now• 1. What about the skeleton

in the photo reminds you of a living thing?

• 2. What about the skeleton reminds you of a nonliving thing?

• 3. What might studying this skeleton help you to learn about living things?

• 4. What might be some benefits of studying living things?

Answers• 1/2. The skeleton is made of organic materials and was

once part of a living thing, but the skeleton cannot move on its own, reproduce, or grow.

• 3. Studying the skeleton could reveal how the internal structure of a living thing is supported, how bones are formed, or how living things grow.

• 4. The study of living things can help people to understand themselves and might lead to practical benefits such as cures for disease, improvements to the environment, and more efficient use of Earth’s resources.

Evolution

Chapters 14 & 15

Objectives• To understand what evolution is.

• To explain spontaneous generation, theory of biogenesis and the primordial soup hypothesis.

What is Evolution?• The change in living organisms over time!

The Origin of Life: Early Ideas

14.2• Where do living things come from??

• Spontaneous Generation:– The idea that life arises from non-life

• Ex: mud gives rise to worms?? We can make mice out of hay??

• Fransisco Redi:– An Italian scientist– Tested the idea of spontaneous generation.

What happens when you leave meat out for a long

time?

Redi’s Experiment- 1668

• He placed meat in both an open container, and a closed container to see what happened…

Redi’s Conclusions• Maggots come from

FLIES, not meat.

• Life must come from life, not spontaneous generation right?– Not completely

rejected until later on…

Now what?• Louis Pasteur

experimented with the “Theory of biogenesis”.

• Theory of Biogenesis:– Only living organisms

can produce other living organisms.

Pasteur’s Experiment

• Tested the idea of spontaneous generation again

• Nutrient rich broth was exposed to air but not dust and spores

Pasteur’s Conclusion

• Living organisms must be able to enter the broth in order to grow

• Living things do NOT spontaneously generate

What about LIFE?• So we know that life can only come from

life… but where did the original life come from???

• What was in the Earth’s atmosphere??

Volcanoes!!• Gases were expelled

from volcanoes– Water Vapor (H2O)

– Carbon Dioxide (CO2)

– Sulfur Dioxide (SO2)

– Carbon Monoxide (CO)

– Hydrogen Sulfide (H2S)

– Hydrogen Cyanide (HCN)

– Nitrogen (N2)

– Hydrogen (H2)

– NO OXYGEN!!!!!!!

How do we KNOW that was what the atmosphere was

made of?• Miller and Urey!

– Created an experiment to show how the first molecules of life could be formed…

– Water + hypothesized gases + electric discharges (boiled)(methane, amonia, (energy: like lightning)

hydrogen)

Amino acids & other organic compounds!

Miller and Urey’s Conclusions

• Primordial soup hypothesis: – early hypothesis about the

origin of life– simple organic molecules

could be made from inorganic compounds.

• Primary Energy Sources:– UV light from the Sun – Electric discharge in

lightning

Overview of Evolution…

Cellular Evolution• Scientists hypothesize that the first cells

were prokaryotes

• Modern prokaryotes called archaea are the closest relatives of Earth’s first cells.

• Archaea are autotrophic

• They do not obtain their energy from the Sun.

Photosynthesizing Prokaryotes

• Photosynthesizing prokaryotes evolved not long after the archaea.

• Prokaryotes, called cyanobacteria, have been found in rocks as old as 3.5 billion years.

Conclusion Activity• State the scientist who came up with

different theories:• 1. Discovered part of cell theory.• 2. Created early earth environment to test

hypothesis.• 3. First to discover that spontaneous

generation was false.• 4. Worked with maggots and meat• 5. Discovered primordial soup hypothesis.

Do Now• Who were the 3 scientists we talked

about and what did each of them do?

Objectives• Determine how cells developed.

• Explain the endosymbiont theory.

• List and describe the steps of natural selection.

Think back…How are prokaryotes and

eukaryotes different?Prokaryotes Eukaryotes

How did we get Eukaryotes?“Endosymbiont Theory”

• Eukaryotic cells lived in association with prokaryotic cells.

• Relationship between the cells became mutually beneficial, and the prokaryotic symbionts became organelles inside eukaryotic cells.

• This theory explains the origin of chloroplasts and mitochondria.

Endosymbiont Theory

Animation• http://highered.mcgraw-hill.com/sites/9834

092339/student_view0/chapter4/animation_-_endosymbiosis.html

Evidence of Endosymbiosis

• Mitochondria have circular DNA like bacteria • Replicates like bacteria separate from the host

cell• DNA codes for proteins that are similar to

bacterial proteins• Mitochondria make their own proteins• Mitochondria have two membranes (one from

the host cell and one from their own cell membrane)

Fast forward a couple billion years…

Who is this guy?

Charles Darwin Darwin was a Naturalist He collect biological and geological

specimens during his travels on his ship the HMS Beagle.

Darwin and the Galapagos Islands

Darwin collected different birds on each of the 4 islands he went to. (mostly finches)

discovered that each island had their own, slightly different varieties of birds.

Populations from the mainland changed after reaching the Galápagos.

Darwin hypothesized that new species could appear gradually through small changes

So What?Darwin Concluded… Humans could

change species by artificial selection, then the same process could work in nature.

• Ex) Corn Selection

Other examples of “artificial selection”

Natural Selection• Some competitors in the struggle for

existence are better equipped for survival than others; those less equipped die.

Natural Selection 1) Individuals in a population show

variations.

Natural Selection• 2) Variations can be inherited.

Natural Selection• 3) Organisms have more offspring than

can survive on available resources.

Natural Selection• 4) Variations that increase reproductive

success will have a greater chance of being passed on.

Use the following example and explain the four parts of

natural selection.• A male peacock has bright colored feathers to

attract a mate– 1. Variation

– 2. Inherited

– 3. More offspring are produced than can survive

– 4.Varations with Reproductive Success

Go through the 4 steps of natural selection with these

moths…

1. What did Darwin infer from his observations of artificial selection?

A. Animal breeders could create new species.

B. A similar process could work in nature.

C. Reproductive success could be increased.

D. Variation in a species could be produced.

2. What is the relationship between natural selection and evolution?

A. They mean the same thing.

B. Evolution works against natural selection.

C. Evolution explains how natural selection works.

D. Natural selection explains how evolution works.

3. Which explains why the tortoises on the different islands of the Galápagos had slightly different variations in their shells?

A. The different tortoises were different species.

B. The environment on each island was different.

C. Each type of tortoise could survive only on its own island.

D. They arrived on the islands from different continents.

Think – Pair - Share

• Brainstorm- How do scientists know that evolution occurred?

• What is some evidence for evolution?

15.2 Evidence for Evolution

• 1. Fossil Evidence

• 2. Evidence from Anatomy

• 3. Embryology

• 4. Biochemistry– Genetic Evidence

• 5. Geographic Distribution

• 6. Direct Observation

1. Fossil Evidence

Fossils provide a record of species that lived long ago.

Fossils show that ancient species share similarities with species that now live on Earth.

2. Evidence from Anatomy

• A. Homologous Parts Anatomically similar structures inherited from

a common ancestor are called homologous structures.

2. Evidence from Anatomy • B. Vestigial Structures

Structures that are the reduced forms of functional structures in other organisms.

Evolutionary theory predicts that these features will become smaller over time until they are lost.

2. Evidence from Anatomy

• D. Analogous Structures:– Can be used for the same purpose (look

similar), but not inherited from a recent common ancestor

– Ex. Wings of an eagle and beetle

Think – Pair - Share

• Compare and contrast analogous and homologous structures.

• List 3 examples of each not mentioned in class.

3. Embryology

• Vertebrate embryos exhibit homologous structures during certain phases of development

• Become totally different structures in the adult forms.

Do Now

• What are homologous structures? Give an example

• What are analogous structures? Give an example

• What are vestigial structures? Give an example

4. Biochemistry

• Common ancestry can be seen in the complex metabolic molecules that many different organisms share.– Ex. Hemoglobin, amino acids

4. Biochemistry – Genetic Evidence

• Mutations are the raw material for evolutionary change

• Genetics can tell us how different groups of organisms are related back through time.

5. Geographic Distribution

• The distribution of plants and animals that Darwin saw first suggested evolution to Darwin.

• Ex. Animals on S. America mainland were more similar to other S. American animals than to animals living in comparable environments in Europe

6. Direct Observations

• Some evolution takes place more rapidly than others

• Ex. evolution of drug resistant bacteria. This type of evolution can be directly observed by scientists.

Conclusion Activity• Match the following with the type of evidence

1. The HIV virus is constantly changing and evolving.

A. Fossil Evidence

2. All living things share the same amino acids

B. Biochemical Evidence

3. Evidence that Dinosaurs were once on earth

C. Embryology

4. Humans and Chimps have similar bone structures

D. Direct Observation

5. The fetus of a pig and dog go through similar developments

E. Evidence from Anatomy

Do Now• What is an adaptation?

• Explain how adaptations are shaped by natural selection.

Adaptations• A trait shaped by natural selection that increases

an organism’s reproductive success• Fitness:

– How well an organism is suited for an environment – How well an organism can pass it’s traits to the next

generation

Types of Adaptation• Camouflage:

– Allows an organism to become almost invisible to predators

Mimicry One species evolves to resemble another

species.

Western coral snake California kingsnake

Speciation • A species is a group of organisms that can

interbreed and produce fertile offspring in nature.• interspecies breeding can sometimes produce

offspring that are infertile such as horses and donkeys producing mules

• Speciation: the development of a new species.

DO NOW• Work on the worksheet as a review of the

evidence of evolution.

15.3 Types of Natural Selection

• Stabilizing Selection– Eliminates extreme

expressions of a trait because the average expression increases survival

• Ex: most human babies are born with average weights

Directional Selection• This happens when an extreme version of

a trait makes an organism more fit. – Ex: when something happens to change the

environment of an organism such as a drought.

Disruptive Selection• A process that splits a population into two

groups because the organisms that express extreme traits survive and the average trait does not.– Ex: Snake coloration

Sexual Selection• Frequency of a trait is based on the ability

to attract a mate.

• Males evolve with threatening characteristics or bright colors to attract females.

Sexual Selection• Peacock Video

Get with a partner!

• Types of Natural Selection worksheet

Patterns of Evolution

1. Divergent Evolution

- Adaptive radiation

- Reproductive Isolation

2. Convergent Evolution

3. Coevolution

1. Divergent Evolution• When one species evolves into two or

more species with different characteristics– One type of Divergent evolution is called

adaptive radiation.

Adaptive Radiation• Can occur in a relatively short time

• One species gives rise to many different species in response to the creation of new habitat or some other ecological opportunity

1. Divergent Evolution (cont.)

• Divergent evolution can sometimes lead to reproductive isolation.

• Prevents two species from mating.

• It can be caused by:– 1. geographic isolation (allopatric speciation)– 2. genetic mutations (sympatric speciation)

• Polyploidy:

Types of Speciation• Allopatric-

– A physical barrier divides one population into two or more populations. Over time each species evolves and can no longer interbreed.

• Ex: grand canyon produced barrier that separated squirrels

• Sympatric-– A new species evolves without a physical barrier.

• Ex: many insect species and plants (polyploidy is a mutation where plants can no longer interbreed with the normal population)

2. Convergent Evolution

• Unrelated species evolve similar traits even though they are not closely related.

• These traits are often structurally very different.

Examples• Bird Wing Bat Wing

Analogous Structures

• Result from Convergent Evolution

• Squid Eye Human Eye

3. Coevolution• The relationship between two species

might be so close that the evolution of one species affects the evolution of the other species.

• Mutualism• Coevolutionary arms race

Garter snake consumes a poisonous newt Orchid Fly

Label the following:

Do Now

• Explain the difference between divergent and convergent evolution

Explain the differences between:

– Homologous and analogous structures– Convergent and divergent evolution

Tempo of Speciation• Gradualism:

– Evolution proceeds in small, gradual steps according to a theory called gradualism.

• Punctuated Equilibrium: – Punctuated equilibrium explains rapid

spurts of genetic change causing species to diverge quickly.

EvolutionChapter 15

What do you think?

• What tempo of evolution does this model represent?– A. gradual– B. elevated– C. sequential– D. punctuated

Do Now

• How did humans evolve?

Primate Evolution

The lineage that most likely led to humans split off from the other African apes sometime between 8 and 5 mya.

Hominins have bigger brains.Thinner and flatter faceSmaller teethHigh manual dexterityBipedal

Hominins

16.2 Hominoids to Hominins

Human Evolution Ch. 16

• Primate adaptations– high level of problem solving ability– large brain size when compared to body

weight– flexible shoulders– flexible hand with an opposable thumb

African Origins

Human Evolution

Conclusion Activity

• Compare and Contrast Apes and Humans