Which of these organisms is the ancestor to the

dolphin?1

2

3

22

45

Manatee ancestor

Sea Lion Ancestor

Seal AncestorIchthyosaurus (EXTINCT)

ANSWER:

1

2

3

22

45

Dolphin Ancestor

OK.....How do we go from THIS ugly cat/crocodile....

To this carefree and happy jester of the sea?

Evolution, or, in Charles Darwin’s words, “Descent with

modification.”

Please write one question on your paper that you have about evolution. If it is not

answered by the end of the lecture, please give this question to Mr. Ross.

Controversy

Evolution has become a “4-letter word” in education, but only in the US. The rest of the world accepts evolution.

Evolution does not mean we are descended from monkeys

Evolution does not prove that God is not real.

Microevolution is REAL, we see it all around. Macroevolution is a bit more complex.

Some people argue that evolution requires faith to believe.

My suggestion: Look at the evidence, make up your own mind. We’ll be dealing with evidence.

What is evolution?

Darwin never used “Evolution” in his writings. He always referred to his theory as “Descent with Modification”.

The offspring of an organism, or pair of organisms, becomes slightly altered (modified) from the parents with each generation

What is evolution?This modification occurs in generations, not in the life of the organism itself.Lamarckian evolution- the idea that organisms can pass on traits to their offspring that they acquired in their lifetime.

Lamarckian Evolution is proven to be impossible because of GENETICS. You can’t change your genes.

How does evolution work?

Natural selection drives evolution. 2 basics for evolution:

1) Genetics- allows traits to pass from one generation to another, provides for biodiversity- variety of life

2) Environmental pressures- Changes in the environment (climate, food availability, space, predators, water) can cause some organisms to survive more and reproduce, while others end up dying.

Dolphin Case Study: From ugly

“cat-croc”, to beautiful “fish-mammal”

To go from one type of organism to a completely different-looking one is called Speciation- the process of creating new species. (Like a cat-crodile to a dolphin)Species- A group of NATURALLY interbreeding organisms

Speciation occurs over long periods of time

Dolphin EvolutionThe original ancestor walked on land.

There was a food source in water. They went after it!

The next generations had some individuals with traits that made them better swimmers (webbed toes, longer/wider feet and paws)

Better swimmers ate more, survived, and reproduced more.

The next generations had more babies with long/wide feet and paws.

Dolphin EvolutionAfter many generations, traits for better swimming were “selected for”.

The environmental conditions determine which traits are “selected” for or against.

Traits that are advantageous stay and enhance over time. Bad traits get lost.

Fossil Record

In the fossil record, we should see Transitional Forms over time. (Intermediate states)

Evolution takes existing traits, and modifies them over time.

In upper layers, the fossils look more similar to Extant (living) organisms. Lower layers look less similar.

Other examples:

Atavism

Sometimes traits that we’ve seen in the fossil record are just “locked up” in the genes and can show up again. They can cause animals to thrive, die, or have no influence at all.

Atavism- a “throwback” to older generations. “RETRO, DUDE!”

Dolphins’ ancestors had 4 limbs. Dolphins currently have 2. BUT, an atavism that shows up in some dolphins is back limbs. They can be selected for or against.

Convergent evolution

Just because something LOOKS related, doesn’t mean it is.

Sometimes environmental pressures can drive organisms to develop the same features over time.

It can be hard to tell what’s related and what’s not. The Tie-breaker after using looks: GENETICS!

Problems with Evolution

How do we get the variety?

Why don’t we find more transitional forms?

Probability

Where did the original living thing come from?

Irreducible complexity

OK, WHOAH....What should I know, Mr. Ross?

Evolution Definitions.

Evolution is driven by natural selection

Environmental conditions select for the best genetic traits

Transitional forms (should) appear in the fossil record.

Question to Ponder

Are Humans subject to evolution?

Transitional Forms Practice!