1. Science Starter

2. How Do Population Changes Happen?
Chapter 4 Section 2
How Do Population Changes Happen?

3. I can explain how variation in each species can occur.
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 describe how some finch species of the Galapagos Islands developed adaptations in response to their environment.
I can describe the four parts of Charles Darwin’s process of natural selection.
I can explain how variation in each species can occur.

4. Charles Darwin (1809-1882) Sailed around the world 1831-1836
In 1831, 21-year old Charles Darwin, graduated from college.
He was not completely sure what he wanted to do with his life, but his main interest was the study of plants and animals.

5. Charles Darwin He signed up for a five year voyage around the world.
He served as the naturalist, which is a scientist who studies nature, on the HMS Beagle, a British ship.
During the trip, Darwin made observations that helped him form a theory about how change happens.

6. Darwin’s Excellent Adventure
Darwin collected thousands of plant and animal samples. He kept careful notes of his observations.
One interesting place that the ship visited was the Galapagos Islands.

7. Darwin’s Finches
Darwin noticed that the animals and plants on the Galapagos Islands were a lot like those in Ecuador, which is in South America. However, they were not identical.

8. Darwin tried to figure out how why some of the finches on the Galapagos Island were similar to the ones in South America.
He first proposed that the first finches were blown from South America in a storm.
He suggested that over many generations , the finches developed adaptations for the various island environments.

9. Ideas About Breeding
In Darwin’s time, farmers and breeders had produced many kinds of farm animals and plants. These plants and animals had traits that were desired by the farmer and breeder.
A trait is a form of a hereditary characteristic.
The practice by which humans select plants or animals for breeding based on desired traits is selective breeding.

10. Ideas About Populations
During Darwin’s time, Thomas Malthus noted that humans have the potential to reproduce rapidly.
He warned that food supplies could not support unlimited population growth.
However, Malthus pointed out that human populations are limited by problems such as starvation and disease.

11. Ideas About Population
After reading Malthus’s work, Darwin realized that any species can produce many offspring.
He knew that some would also die due to starvation, disease, competition, and predation.
Only a limited number of individuals live long enough to reproduce.
Thus, the survivors are special, and their offspring would inherit traits that help the offspring survive their environment.
Rabbits vs Wolves

12. Ideas About Earth’s History
Darwin had begun to think that species could slowly change over time.
However most geologists did not think that the Earth was old enough to allow for slow changes.
However, Charles Lyell wrote a book that presented evidence that the Earth had formed by natural process over a long period of time.
It was clear that the Earth was much older than most had imagined.

13. Darwin’s Theory of Natural Selection
After his voyage around the world, Darwin struggled with his ideas for a good 20 years.
In 1858, Darwin received a letter from a naturalist name Alfred Russel Wallace who had came up with the same ideas as Darwin.

14. Darwin’s Theory of Natural Selection
In 1859, Darwin published a famous book called On the Origin of Species by Means of Natural Selection.

15. Darwin’s Theory of Natural Selection
In his book, Darwin proposed the theory that change in populations happens through natural selection.
Natural Selections the process by which organisms that are better adapted to their environment survive and reproduce more successfully than less well adapted organisms do.
The process has four parts.

16. Darwin’s Moth

17. Moth Pollination of Orchid

18. Genetics and Inherited Traits
Darwin knew that organisms inherited traits, but not how they inherited traits. He also knew there was a variation in organisms, but he did not know how that variation occurred.
Scientists know that variation happens when genetic information is passed from parent to offspring.
Some genes make an organism more likely to survive to reproduce.
The process called selection happens when only organisms that carry these genes can survive to reproduce.

19. Pepper Moth Activity

20. I can explain how variation in each species can occur.
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 describe how some finch species of the Galapagos Islands developed adaptations in response to their environment.
I can describe the four parts of Charles Darwin’s process of natural selection.
I can explain how variation in each species can occur.