EVOLUTIONThe unifying theme of biology

BELLRINGER

Make these 3 columns and jot down a few ideas

First thing you think of when you hear “evolution”

What do you know about evolution?

What questions do you have about evolution?

THE INS AND OUTS

That all species are related and came from one ancestral species

That species change over millions of years and can become new species or split into separate species

That the earth is much older than biblical accounts

That there is no God or creator

That we evolved from monkeys or that monkeys should each evolve into humans

That animals should give birth to brand new species overnight

Evolution does argue…Evolution does not argue…

EVOLUTION DOES NOT ADDRESS

How life beganMoralityWhether species are “better” or “higher order”

The meaning of life or significance of “being human”

THERE IS VERY LITTLE SCIENTIFIC DEBATE

Scientists debate the details of evolution but there is overwhelming consensus that evolution does occur

There is a lot of evidence

BUT EVOLUTION IS A THEORY…

A “theory” in science is a well-supported argument that matches all experimental evidence and is widely accepted – like gravity

Scientists never say we “prove” or we “know”. We say “the data suggests or supports”

THE FIRST PERSON TO SUGGEST EVOLUTION WAS… NOT Charles Darwin, but

Jean Baptiste Lamarck revived an idea that existed for thousands of years

Suggested species change over time and can become new species

BUT he had no evidence, and his hypothesis did not properly explain how evolution could occur

CHARLES DARWIN

Proposed a well-thought out, coherent, well-researched hypothesis

Was scared to publish for many years- in fact a man named Alfred Wallace published at the same time

But Darwin’s version was more complete so he gets all the credit

DARWIN’S VOYAGE

Visited the Galapagos Islands

Upon careful observations (the beginning of the scientific method!) he began to believe all species must be related

Let’s see what he saw!

While we watch “Into the Galapagos” please make a list of all the living species that we see

TODAY

1. Survey on STEM2. Practice ACT3. Evolution by Natural

Selection4. Computer lab research on

evidence for and against evolution

2 MAIN PARTS TO THE THEORY

Species change New species form

from old species All species came

from one common ancestor (this was a bit of a leap of faith on his part)

The theoretical mechanism that causes change

Environment selects which traits become common (like selecting dog breeds)

Descent with Modification

Natural Selection

NATURAL SELECTION

Individuals compete for resources and mates

Certain genes cause some individuals to outcompete others

That means these genes become more common

Less favorable genes become less common or disappear

Over long periods of time these favorable genes accumulate and the population will be very different than its ancestors

NATURAL SELECTION

Traits that help individuals survive and reproduce become more common

Incredibly complex organisms come about after millions to billions of years of small changes

EXAMPLEhttp://www.youtube.com/watch?v=iraaygtYSYk&feature=related

WHAT IS ADVANTAGEOUS DEPENDS ON THE ENVIRONMENT

White moths were common in London before industrial evolution

After- soot covers most of the city and black moths become common

EXAMPLE

NATURAL SELECTION AND GIRAFFES

NATURAL SELECTION AND SPIDER REPRODUCTION

In some spider species the male leaps into the jaws of the female

He is killed and eaten but his sperm reaches the female

Genes that contribute to this behavior have evolved because they get passed on

HOW DO WE KNOW THIS IS PLAUSIBLE?

We have created many new species by selecting which ones reproduce

SUBTLETIES OF NATURAL SELECTION Only traits that are

already present can be selected for

New traits come about by random mutations

No such thing as perfect- everything is a compromise

INDIVIDUALS DO NOT EVOLVE

MORE SUBTLETY IN NATURAL SELECTION

Individuals don’t necessarily TRY to survive or reproduce

Genes that contribute to success become common

Non-fit individuals die and do not pass on genes

REST OF TODAY

Go to computer lab for research on evidence for evolution as a group

Should be a short, quick presentation (4-5 slides) - that you are ready to present Friday. Email me the presentation before Friday

RESEARCH – DOWN IN THE COMPUTER LAB

Research one of the types of evidence

Explain how it provides evidence for evolution by natural selection in your own words

Give a few examples

Find some arguments against evolution by natural selection

Try to find some that sound scientific and plausible- not just rants and raves We’ll see if we can

explain their observations in terms of evolution

1. Evidence for Evolution

2. Evidence/arguments Against Evolution

EVIDENCE FOR YOU TO RESEARCH

BiogeographyComparative embryologyHomologous structuresVestigial structuresFossilsDNA analysisProtein analysis