1. Chapter 4: Population Changes
Section 1: Change Over Time

2.
Analyze data on levels of variation within a population to make predictions about survival under particular environmental conditions.
Proficient I Can:
I can analyze data changes within a population to make predictions about an organisms survival under specific environmental conditions.
Basic I Cans:
I can identify two kinds of evidence that show organisms have changed over time.
I can identify how the fossil record shows changes in the kinds of organisms in the environment have been occurring over time.
I can describe one pathway through which a modern whale could have arisen from an ancient mammal.
I can explain how comparing organisms can provide evidence that they have ancestors in common.

3. Change Over Time
If you described a snake, you might say that a snake has a long, narrow body has a forked tongue, and hisses. But what color skin would you say that a snake has?

4. Change Over Time
All these snakes look different from one another, yet they all live in the same area.
Once you start to think about snakes, you realize that snakes differ in many ways. These differences set one kind of snake apart from another.

5. Differences Between Organisms
As you can see from the previous pictures, the snakes have different characteristics that help them survive.
A characteristic that helps an organism survive and reproduce in its environment is called an adaptation.

6. Differences Between Organisms
Some adaptations are physical
Examples
Long neck
Striped fur
Other adaptations are behaviors that help an organism find food, protect itself, or reproduce.

7. Differences Between Organisms
Living things that have the same characteristics may be members of the same species.
A species is a group of organisms that can mate with one another to produce fertile offspring.
For example:
All eastern diamondback rattlesnakes can mate with each other to produce fertile eastern diamondback rattlesnakes.

8. Differences Between Organisms
Eastern grey kangaroo estimate population in 1996 was 10'000'000
Groups of individuals of the same species living in the same place make up a population.
Red kangaroo estimate population in 1996 was 10'000'000
Western grey kangaroo estimate population in 1996 was 3'000'000

9. Do Species Change over Time?
Scientists think that Earth has changed a great deal during its history and that living things have changed, too.
Scientist estimate that the planet is 4.6 billon years old.
Since life first appeared on Earth, many species have died out, and many new species have appeared.

10. Evidence of Changes Over Time
Evidence that organisms have changed over time is buried within Earth’s crust.
The layers of earth are made of sediments, or particles of sand, dust, and soil that are carried by wind and water and are deposited in an orderly fashion.

11. Fossils
The remains or imprints of once-living organisms found in layers of rock are called fossils.
Fossils can be of the complete organism, parts of the organism, or just a set of footprints.
The organisms is covered by a layer of sediment and eventually leaves an imprint in the rock.

12. The Fossil Record
By studying all the different fossils, scientists have made a timeline of life known as the fossil record.
The fossil record organizes fossils by their estimated ages and physical similarities.
Comparing organisms in the fossil record can reveal how organisms have changed over time.

13. Evidence of Ancestry
The fossil record provides evidence about the order in which species have existed.
Scientists observe that all living organisms have characteristics in common and inherit characteristics in similar ways.
Scientists think that all living species descended from common ancestors.

14. Drawing Connections
Scientists examine the fossil record and make diagrams to show how organisms are related.
The short horizontal line represents a species that lived in the past.
Each branch represents a group of organisms that descended from that species.

15. Examining Organisms
Examining an organism carefully can give scientists clues about its ancestors.
Example:
Whales seem similar to fish. But unlike fish, whales breathe air, give birth to live young, and produce milk.
This shows that whales are mammals and that whales may have arose from ancient mammals.

16. Case Study: Origins of the Modern Whale
Scientists think that the ancient ancestor of whales was probably a mammal that lived on land and that could run on four legs.
A more recent ancestor was probably a mammal that spent time both on land and in water.

17. Transparency

19. Walking Whales
Further evidence can be found inside the bodies of living whales to support that their ancestors were able to walk and live on land.
Modern whales do not have hind limbs, however inside their bodies are tiny hip bones.
Scientists think that these hip bones were inherited from the whales’ four-legged ancestors.

20. Comparing Organisms
Evidence that groups of organisms have common ancestry can be found by comparing the groups’ DNA.
Because every organism inherits DNA, every organism inherits the traits determined by DNA.

21. Comparing Skeletal Structures
What do your arm, the front leg of a cat, the front flipper of a dolphin, and the wing of a bat have in common?
You might notice that these structures do not look alike nor are they used in the same way.

22. Comparing Skeletal Structures
This suggests that all four have a common ancestor, but over time the bones developed to perform different functions in each animal.
Under the surface, all four things have something in common.
The structure and order of bones of a human, are similar to those of the front limbs of a cat, a dolphin, and a bat.

24. Comparing DNA Molecules
Another way for scientists to determine if an organism is related to another is by comparing DNA, RNA, and proteins in different organisms.
The more similarities organisms have between each other, the more closely related they may be to each other.

25.
Analyze data on levels of variation within a population to make predictions about survival under particular environmental conditions.
Proficient I Can:
I can analyze data changes within a population to make predictions about an organisms survival under specific environmental conditions.
Basic I Cans:
I can identify two kinds of evidence that show organisms have changed over time.
I can identify how the fossil record shows changes in the kinds of organisms in the environment have been occurring over time.
I can describe one pathway through which a modern whale could have arisen from an ancient mammal.
I can explain how comparing organisms can provide evidence that they have ancestors in common.