1. Variation in Populations Tennessee SPI Objective:
Notes
Science
Tennessee SPI Objective:
Analyze data on levels of variation within a population to make predictions about survival under particular environmental conditions.
Essential Question
1) What is the link between genetic variations within a
population, environmental conditions, and the survival rate of sub-groups within that population?
Success Criteria
1) I can explain the link between genetic variations, the
environment, and survival rates.
2) I can analyze data relating to survival rates and variations within a population of organisms.

2. Variation in Populations
Variation refers to a variety or diversity of traits
(different kinds) within any given population.
Three causes of variation
1) Diversity of genetic traits from sexual reproduction
2) Diversity of genetic traits that result from mutations
3) Response to changing environmental conditions
Variation in human populations
Look around at the other students.
Notice the unique traits that individuals have such as hair color, height, eye color, skin color, etc.
Variation in wild populations
variations occur in nature in populations of plants, animals, birds, insects, fish, bacteria etc.

3. Notes SPI 0807.5.2 Adaptations 1) When environmental changes occur…
Science
1) When environmental changes occur…
…organisms must change (adapt) by either changing their behavior or changing their body structure or both.
2) The process that drives this…
… is called natural selection.
3) Changes and variations in populations result from…
…sexual reproduction (over many generations) and changes in the environment.
4) Changes and variations also result from…
…genetic mutations (over many generations)
and changes in the environment.

4. Four Phases of Natural Selection
Bunny Rabbits
Overproduction
Too many offspring are born.
Phase 1
Genetic Variation in a Population
Offspring are born with a variety of traits. Some offspring are better suited to survive than others.
Phase 2
Genetic Variation in a Population
Offspring are born with a variety of traits. Some offspring are better suited to survive than others.
Struggle to Survive
Offspring compete for limited resources. Many die or are eaten by predators.
Phase 3
Successful Reproduction
The stronger, smarter, faster offspring survive to breed with each other.
Phase 4

5. 4 Phases of Natural Selection
Spiders
Phase 1
Phase 2
Phase 3
Phase 4

6. Variation in Populations
The Galapagos Islands are located in the Pacific Ocean about 600 miles west of Ecuador (see picture below).
At some point in the past, a small population of Finches (birds) were blown from South American to these islands.
Each island has a slightly different ecosystem, and these finches adapted accordingly. This lead to significant variation in the shapes and sizes of their beaks.
South American Finch
Galapagos Islands
Consists of 18 larger islands
and 3 smaller islands.

7. Variation in Populations
Over time the finches developed different beak shapes and sizes in order to eat the local food (structural adaptations).
Food Source
Only Bugs
Food Source
Nuts & Bugs
Food Source
Only Nuts
narrow-pointed beak for eating insects
Moderately wide beak with a sharp point for cracking nuts and eating insects
Very wide beak for only eating nuts

8. Finches on the Galapagos Islands
Essential Question
What is the link between genetic variations, the environment, and
the survival rate of sub-groups in the population?
Finches on the Galapagos Islands
Due to the genetic diversity inherent in sexual reproduction, the population of Finches had offspring born with a variety of traits.
This included different shaped beaks.
Some Finches were born with larger/wider beaks.
Some were born with narrow/pointed beaks.
Food Sources
Some islands have an abundance of seeds/nuts while other islands have an abundance on insects.
Larger/stronger beaked offspring thrived on islands with seeds.
Sharper/narrow beaked offspring thrived on islands with insects.
On each island, Finches with the most effective beaks dominated
while those with less effective beaks died out (Natural Selection)

9. Review Questions

10. Note: Termination refers to the percentage of bugs that were killed
Review Questions
Note: Termination refers to the percentage of bugs that were killed

11. Review Questions

12. Review Questions

13. Review Questions