Regents Biology 2006-2007

by Natural Selection

Evolution…

Regents Biology

1. What is Evolution? Evolution

changes in living organisms over time explains how modern organisms have

descended from ancient organisms

Evolution!

Why do we accept this as aScientific Principle?

Regents Biology

2. What do we know? A. There are many different creatures on Earth

How do we know this?

Diversity of Life on Earth

OBSERVATION

How did all these creatures come about?What accounts for all this biological diversity?

Biodiversity of Life on Earth

Regents Biology

What do we know? B. All creatures have common characteristics

How do we know this?

DNAcells

Unity of Life on Earth

How could all of life have the same basic features?

OBSERVATION

Regents Biology

What do we know? C. The Earth is very old

How do we know this?

Radioactive Datingof the Rocks

TESTING & OBSERVATION

Life is very old!

What’s happened to life during those billions of years?

Regents Biology

What do we know? D. Creatures have changed over time

How do we know this?

Fossil Record

OBSERVATION

Regents Biology

3. What has the fossil record shown us? A. Many creatures that lived in the past

don’t exist today

Origin of new species

OBSERVATION

Regents Biology

What has the fossil record shown us? B. The creatures alive today haven’t

always been around

Different species lived in the past

OBSERVATION

Regents Biology

What has the fossil record shown us? C. Many creatures in the past looked

like living ones we see today

“Family Tree”Relatives with

similar, but not the same traits

OBSERVATION

Regents Biology

4. Quick review, so far….a) Many different species alive todayb) All life shares common characteristicsc) The Earth is very oldd) Life is very olde) Life has changed over timef) The changes have been little changes

over long periods of time

Evolution

But how does this work?

Regents Biology

5. What do we know? A.Populations are a mix of different individuals

How do we know this? OBSERVATION

Variation

Regents Biology

What do we know? B. Organisms have more offspring than the

environment can support C. Not everybody survives E. How do we know this?

OBSERVATION

Over-production

Competition

Regents Biology

6. How does that work?Variation

Over-Production & CompetitionNature selects the ones that “fit” the

environment better … survive & reproduce

Adaptation

Natural Selection

Regents Biology

7. What determines survival? traits that help individuals survive

survive predators survive disease compete for food compete for territory

traits that help individuals reproduce attracting a mate compete for nesting sites successfully raise young

Survival & Reproduction of the Fittest

Adaptations

Regents Biology

Survival & Reproduction of the fittest

not the strongest…not the bravest…not the fastest…not the biggest……the fittest!

the traits that help an organism fit the environment better to

survive & reproduce

Adaptations

Regents Biology

8. Darwin’s Theory of Natural Selection

#1 Overproduction Organisms tend to have many more than two

offspring so at least some will survive (yet populations usually do not grow rapidly in the wild)

Regents Biology

#2 Competition - Therefore they must compete for resources

(food, space, mates)

Regents Biology

Natural Selection #3 Variation - There is

variation within the population.

#4 Adaptation - Therefore some of them must be better adapted to their environment

Regents Biology

#5. Natural Selection- the ability of organisms that are best adapted to survive and reproduce . Those that are less well adapted will not survive.

Regents Biology DNA

9. Evolution explains Unity & Diversity Evolution explains both unity of life

similarities between all living things diversity of life

wide variety of different creatures on Earth