evolution pre ap biology spring 2013. what is evolution? definition (memorize this!!) : –gradual...

Evolution

Pre AP Biology

Spring 2013

What is Evolution?

• Definition (memorize this!!) :– Gradual change in the genetic makeup of a

species over a long period of time

• Notice the terms gradual change and time. These changes are difficult for us to understand because they occur across many generations and therefore cannot usually be observed in our lifetime. Most changes occurred before recorded history.

What evolution is not

• Evolution is not “we came from monkeys.”

• Evolution is not “how life began on earth.”

• Evolution is not “the Big Bang” theory.

• Evolution does not say that God doesn’t exist.

• Evolution is not “just a theory” without any proof.

Questions we can’t answer in science class:

• Does God exist?• Did God create the Universe, the world, and/or us?• What is a soul?• Who goes to heaven?• What happens after we die?

None of these questions can be answered using the scientific method and so they fall outside the realm of science.

That doesn’t mean they aren’t good questions or that they aren’t worth asking, but they won’t be answered in this class.

I’m not telling you what to believeYou will not be tested on whether you think

the theory of evolution is “right or wrong” You will be expected to know:• the definition of evolution• Details about Darwin and his findings• The proof that we have of evolution (5

major categories of proof and examples of each)

• Natural selection and how it works as a mechanism for evolution.

Charles Darwin

• Darwin was always interested in the natural world.

• He came from a wealthy family and was expected to be a doctor.

• He went to college to study medicine and hated it…he dropped out.

• In 1827 he went to Cambridge to study theology and become a minister.

• Still, he was more interested in the natural world.

Charles Darwin

Born 1809

Died 1882

The voyage that changed everything

• At the age of 22, Darwin was hired to be a naturalist on board a survey voyage. The ship was the HMS Beagle.

• The Beagle was a survey ship that was

sent to collect

information about

the coastline of

South America.

Are we there yet? Reading to pass the time:

• On the voyage he read a book by a geologist (Charles Lyell’s Principles of Geology)

• The book theorized that the surface of the earth changed slowly over many years.

• Using this information, not only did Darwin realize that the earth must be very old, but he became convinced that the same thing (gradual change) happened to species.

What he observed on the voyage

• The animals and plants in South America looked more like each other than the plants and animals in similar climates in other parts of the world.

• S. A. fossils looked like current S. A. plants and animals.

• Plants and animals found on islands close to South America (Galapagos Islands) were similar to the ones on the mainland.

Galapagos Islands

After the voyage

• Darwin returned from the voyage and studied his notes along with other scientists’ essays.

• Published his observations in a book On the Origin of Species by Means of Natural Selection in 1859.

• The book had 2 major points:– Organisms have changed over time (Darwin called

this “descent with modification”. We call it evolution)– Organisms change because of natural selection.

Natural Selection

• Darwin studied Artificial Selection – We have bred animals and plants to suit purposes…we select the traits we like.

Natural Selection• Natural selection is also called “survival of the

fittest.” • Natural Selection says that individuals that have

physical or behavioral traits that better suit their environment are more likely to survive and reproduce than those that do not have such traits.

• In order to work the following conditions have to be met: – Harsh environment– More offspring than can survive– Variation within the offspring

Proof of Evolution

• Five major points that we use to support the theory of evolution:

1. Fossil Record

2. Homologous Structures

3. Vestigial Organs

4. Amino Acid sequences

5. Embryology

Fossil Record

Evolution can be seen in the fossil record.

Darwin predicted and we have found thousands of “transitional forms” that link ancestors and current organisms.

Examples: page 284 and 285 in your book

Also horse transitional forms

Fossil Record

Archaeopteryx

Significant because it shows the transition from reptile to bird.

Tiktaalik

http://en.wikipedia.org/wiki/File:Fishapods.png

Homologous Structures

• Structures that are similar in more than one species

• Used to support a common ancestry.

• Example: Common mammal forearm / leg / flipper.

See page 286 in your book

Vestigial Structures

• Organs or structures that are reduced in size and seem to have little or no function.

• Vestigial structures are considered to be evidence of an organism’s evolutionary past

• ex: Whale’s pelvic bone, blind salamander eye socket, our appendix, our wisdom teeth.

Snake Feet

Amino Acid sequences.

• Look at page 287 for an example,

• Species descended from a recent common ancestor have fewer amino acid differences between their proteins than do species that have a common ancestor further back in time.

Amino Acid Sequence

• We can take amino acid sequence differences and graph them to create a phylogenic tree. A phylogenetic tree shows relationships and common ancestory using some trait (in this case, amino acid sequences.)

Terminal = a taxonomic group; These usually represent living species, genes, or proteins that are still around today.

Branches = the lines in a phylogenetic tree that connect terminals to nodes or one node to another

Nodes = points in a tree where branches intersect; they the represent ancestors of all escend from them.

MRCA (most recent common ancestor) = the latest ancestor shared by a group of terminals;

Clades = natural groups of organisms

Tree of Life

• Tree of life video

David M. Hillis, Derrick Zwickl, and Robin Gutell, University of Texas.

http://archive.peabody.yale.edu/exhibits/treeoflife/

Embryology• All vertebrate embryos

have similar structures.

• All have a tail, buds that become limbs and pharyngeal pouches.

• We lose the tail. Mammals, birds and reptiles lose the pharyngeal pouches…in fish and amphibians they become gills

Study of Natural Selection• Find a group of 2 or 3. There is not

enough supplies for anyone to work on their own.

• ALL of you need your own data table, a ruler, and a pencil.

• For your group, someone should obtain a deck of cards and a calculator from the front of room.

Study of Natural Selection

• The cards represent the population and the number on the card represents the height (in feet) of the individuals.

• Jot this down in the top margin of your paper so you don’t forget: Aces = 1 foot, King=13 feet, Queen=12 feet, Jack=11 feet and all the others = number on card

Sampling

date

Sample

#

Height of organisms (in feet) Average

height of

sample

1 2 3 4 5 6

2001

1

2

3

X X X X X X X 2001 Avg.:

2005

1

2

3


2009

1

2

3

X X X X X X X 2009 Avg:

2013

1

2

3


2001 Procedure

1. Sample #1 – Shuffle the cards. Draw 6 cards from the deck. Record the number show on each card on the data table as height of organisms.

2. Calculate the average to fill in last column

3. Return the 6 cards to the deck and shuffle

4. Repeat these steps 1-3 for days two and three. (samples 2 and 3)

Sampling

date

Sample

#


height of

sample

1 2 3 4 5 6

2001

1

2

3


2005

1

2

3


2009

1

2

3


2013

1

2

3


2005 Procedure

• During the years from 2001 to 2005 all the vegetation below the height of 5 feet has been devoured by caterpillars.

• Remove all the cards with numbers lower than 5 (Ace – 4). set these cards aside and shuffle remaining cards.

1. Sample #1 - Draw 6 cards from the deck. Record the number show on each card on the data table as height of organisms.

2. Calculate the average to fill in last column3. Return the 6 cards to the deck and shuffle4. Repeat these steps 1-3 for days two and three.

Sampling

date

Sample

#


height of

sample

1 2 3 4 5 6

2001

1

2

3


2005

1

2

3


2009

1

2

3


2013

1

2

3


2009 Procedure

• During the years from 2005-2009 all the vegetation below the height of 7 feet has been devoured by caterpillars.

• Remove all the cards with numbers lower than 7. set these cards aside and shuffle remaining cards.



Sampling

date

Sample

#


height of

sample

1 2 3 4 5 6

2001

1

2

3


2005

1

2

3


2009

1

2

3


2013

1

2

3


2013 Procedure

• During the years from 2009-2013 all the vegetation below the height of 9 feet has been devoured by caterpillars.

• Remove all the cards with numbers lower than 9. set these cards aside and shuffle remaining cards.



Sampling

date

Sample

#


height of

sample

1 2 3 4 5 6

2001

1

2

3


2005

1

2

3


2009

1

2

3


2013

1

2

3


Chart and Graph your data

• In your journal you will need a chart that summarizes your data…it should have the average height for the population for each year it was calculated. Remember that charts have a title and use a straight edge. Do not simply copy your original data table. This one should be a summary.

Chart and Graph your data

• Underneath your chart, graph average height in the population for each year. Decide what kind of graph is best and remember all the parts a graph should have.

• Below the graph copy and answer the questions that follow.

• This is due next class, if you don’t finish it today.

Questions

1. If conditions described in this study remained the same, what adaptations could you expect from the population?

2. Explain how this lab models natural selection.3. Why did the card with the higher numbers

have an advantage over the cards with the lower numbers?

4. Is height always an advantage to organisms? Why or why not. Give examples to support your answer.

In summary• Who? you• Where? In your journal• What?

– A chart that summarizes the data– A graph of average height for each year– Copy and answer the following questions

1. If conditions described in this study remained the same, what adaptations could you expect from the population?

2. Explain how this lab models natural selection.3. Why did the card with the higher numbers have an advantage over the cards

with the lower numbers?4. Is height always an advantage to organisms? Why or why not. Give

examples to support your answer.

• When? Due next class period.• What else? Use a ruler, give charts and graphs a title

Co-evolution

• Co-evolution occurs when 2 different species both evolve in reaction to each other.

• 2 great examples:– Plants and herbivores– Flowers and pollinators

ADAPTATION

• Remember that each species has adaptations that help it fit perfectly into its specific niche (location and role)

• Remember that individuals cannot adapt. A species adapts as helpful mutations assist some organisms in being more fit and those mutations are passed on

A couple more terms

• Biogeography – A study of the geographic distribution of organisms.

• Convergent Evolution – organisms living in the same area evolve structures that are similar (analogous) in spite of their evolutionary ancestors being very dissimilar or unrelated.

• Example of analogous structures: – butterfly and bird wing;– fusiform shape of dolphins, tuna,sharks, and

penguins.

http://www.biology-online.org/dictionary/Analogous

Forces in Evolution

• Genetic Drift – a small population will exaggerate a difference resulting in speciation. – Founder’s effect– Bottleneck effect

• Gene flow – new alleles coming into and going out of a population

evolution pre ap biology spring 2013. what is evolution? definition (memorize this!!) : –gradual...

Documents

theory of evolution

survey voyage

natural world

charles darwindarwin

survey ship

study medicine

study theology

hms beagle