Evolution

Theory of EvolutionTheory:

Evolution:

Theory of Evolution:

Misconception: Evolution is a theory about the origin of lifeResponse:

Misconception: Evolution is ‘just’ a theoryResponse:

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Early Ideas on The Origin of Species

Lamarck’s ides• Traits acquired during a lifetime can be

passed on

• Changes are the result of species trying to change

What’s wrong with that idea--(If you cut the tail off of a mouse, will it have

tail-less babies?)

What we learned from Mendel.

--(Do bacteria become immune to antibiotics because they are trying too?)

(Because the giraffe keeps stretching its neck, its neck gets longer, and that trait gets passed on to its offspring)

(Beavers tried to be really good at cutting down trees, so they got better at it)

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Darwin’s Story• Darwin was a naturalist aboard the HMS Beagle on an

expedition to chart the coastline of South America. His job was to observe and record the wildlife. The Galapagos Islands are a small group of volcanic islands in the Pacific ocean, off the coast of Ecuador

• He saw many organisms on these islands that resembled organisms from the mainland but were strikingly different:– Giant tortoises: Weigh about 225 kg (No competitors or

predators on the island)– Marine iguanas: Only known sea going lizards! They have

webbed feet and a flattened tail.– Finches: Similar in size, great diversity among their beak

structure depending on their food source.

• Based on his observations, he proposed that:

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Darwin’s Conclusions

1) Overproduction:

2)Variation:

2a)Inheritance of variance:

3) Competition:

4)Natural selection:

5) Speciation:

5a)Decent with modification:

5b) Common ancestry:

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1) OverproductionOverproduction: Not all of the offspring produced will survive, and many

of those that do survive, do not reproduce. - 1000 fish in a tea cup; How many survive?

Variation: Individual organisms in nature differ from one another, and some of this variation is inherited

Where does this variation come from?1)

2)

Misconception: Populations can’t change over timeResponse:

2) Variation

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3) CompetitionCompetition: Since there are more organisms produced than can survive, members of each species must

compete for limited resources

Its really all about sex!! (reproduction)

Everything wants to pass on its genes. In order to do that you need to compete for:

If you manage to secure these things, then you then need to compete for:

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4) Natural SelectionNatural Selection: Process by which individuals that are better suited for their environment survive and reproduce

most successfully.

In other words: There is a lot of variation between individuals. The ones with the best traits for that environment are going to naturally be more successful, and have more offspring than those that are poorly suited for their environment.

This process has been mimicked by humans:Artificial selection: Instead of nature selecting which organisms are best suited for the environment, humans

do the selecting for what will survive and reproduce.Also known as:

Misconception: Natural selection involves organisms ‘trying’ to adaptResponse:

What happens if nothing is fit?______________________Misconception: Natural selection gives organisms what they ‘need.’Response:

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The Peppered Moth

1) Overproduction and Variation

2) Competition and Natural SelectionLight Trees Dark Trees

Light Colored Trees Dark Colored Trees

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3) Resulting PopulationLight Trees Dark Trees

Misconception: Evolution means that life changed ‘by chanceResponse:

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These moths spend time on the woodlands outside of industrialized areas. The trees are normally light but because of pollution they become dark

5) Speciation

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Speciation: Formation of new species

How can this occur?There are a few different things that lead to speciation (open your books to 404-405 and read isolating

mechanisms) :Behavioral Isolation:

Geographic Isolation:

Temporal Isolation:

Why does Isolation lead to speciation?

Phylogenetic Trees

--Shows speciation and the evolutionary relationships among various biological species

--As you go towards the base of the “tree”, you are going farther back in time (Millions of years)

--At the top of the tree are species that currently exist.

--Which species is the most closelyrelated to Dogs?

1) The Coyote2) African Wild Dog

How did you figure that out?

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History of lifeHow quickly does evolution operate?Like in other things, change can either come quickly, gradually, or a by a

combination of the two. For Evolution, there are Gradualism:

Punctuated Equilibrium:

*Remember, “rapid” is relative to geologic time, which could still mean MILLIONS of years!

0.2 Million years ago:

700 Million years ago: Multicellular organisms evolve

2.1 Billion years ago: Eukaryotic cells appear (cells with internal membranes).These cells were then able to incorporate bacteria that would become their organelles!

2.2 Billion years ago: Photosynthetic organisms evolved, putting oxygen into the atmosphere.

3.5 Billion years ago: Single celled organisms that lived on an Earth that has NO Oxygen in the atmosphere4.5 Billion years ago: Earth Formed 11

1. Fossils:

Although the fossil record will never be complete, it contains striking evidence that evolution has occurred-Many types of remains can be found:

Radiometric Dating: Allows for the age of fossils to be determinedMoldimpression made in the substrate - a negative image of the organism

Castformed when a mold is filled in

Trace:Evidence of life forms•Tracks•Nests•Eggs•Coprolites (feces)•Tooth marks

Petrified: rock-like minerals seep in slowly and replace the original organic tissues with silica, calcite or pyrite, forming a rock-like fossil

True form fossils: remains of actual organisms•In ICE•In Amber•La Brea Tar Pits

How Fossils help--

Example: Archaeopteryx and the origin of Birds• jaws with sharp teeth• three fingers with claws• a long bony tail

- Not quite a dinosaur, not quite a bird. An organism that is transitioning from one thing to another

Archaeopteryx

Evidence of Evolution

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Species Amino Acid Differences compared to human hemoglobin

a. Gorillab. Rhesus Monkeyc. Moused. Chickene. Frogf. Lamprey

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274567

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Create a phylogenetic tree that uses this data

Evidence of Evolution

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2. Comparative Biochemistry:

All known organisms are based on the same fundamental biochemical organization:

• Genetic information coded as nucleic acids DNA transcribed into mRNA then translated into proteins

•The Genetic Code (the "translation table" between DNA and amino acids) is the same for almost every organism, meaning that a piece of DNA in a bacterium codes for the same amino acid as in a human cell. •ATP is used as energy currency by all life.

•Chlorophyll is the same basic molecule in all photosynthetic organisms

•Hemoglobins are found in a wide variety of life forms and they are all very similar in structure.• The differences between their amino acid sequences can be used to determine how closely related different

species are•

Evidence of Evolution

• Homologous Structures:

• Implies descent with modification:

• Structures have changed over time as the organism evolved

• Vestigial Structures: Structures are present in an organisms but useless or have a less prominent function

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• Examples: Cave dwelling animals with eyes, the human appendix, coccyx, and ear muscles

3. Comparative anatomy:

4. Comparative Embryology: the study of

- Comparing these stages may show similarities that suggest a common ancestry

Can you tell which embryo will develop into what organism by looking at the earliest stage of development?

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1. INDUSTRIAL MELANISM:

The population changed from light colored moths to dark colored moths because the light ones would be eaten by birds

Found in light wooded forests in England

As pollution increased, the trees became darker colored

2. INSECTICIDE RESISTANCE IN INSECTS:

3. RESISTANCE TO ANTIBIOTICS IN BACTERIA:

*These traits naturally occurred in the populations and the change in the environment lead to different traits being favored. This causes a change in the allele frequency of the population,

Why is having diversity and variety in a population important?

Misconception: Evolution is not science because it is not observable or testableResponse:

Recent Evolution

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