1. Evolution & Natural Selection
Write Green!
Chapter 13
Lesson 2

2. Observed tortoises, mockingbirds and finches.
1. Who is Charles Darwin
A naturalist that explored the Galapagos Islands, in which he proposed the Theory of Natural Selection.
Observed tortoises, mockingbirds and finches.

4. Wait….that’s confusing??
What is Natural Selection?
the process by which organisms with variations that help them survive in their environment, live longer, compete better and reproduce more than those that do not have these variations.
Wait….that’s confusing??

5. 2. How does genetic variation & environmental factors contribute to evolution by natural selection and diversity?
Variation is a slight difference in an inherited trait of individual members of a species.

6. 3. How does variation happen?
An adaptation variation (change) that makes an organism better suited to it’s environment.
Structural
Physical characteristics. Color, beak shape, etc.
Camouflage and mimicry.
Behavioral
Hunting at night, moving in herds and conserving energy.
Functional
Internal body systems affecting biochemistry.

7. How many adaptations does this arctic fox have?

8. Natures Best Camouflages!

9. 4. Why is Variation Important?
Well, the environment changes!
The more variation within a species, the more likely it will survive.
If everyone is the same, then all are vulnerable to same environmental changes or diseases
The more variation of types of species in a habitat, the more likely at least some will survive.
Dinosaurs replaced by mammals

10. Which community has a better chance of surviving a natural disaster?
Community A
Community B

11. 5. Competition Individuals COMPETE for limited resources
Food, water, space and mates
Natural selection occurs through “survival of the fittest”
Fitness: the ability to survive and reproduce
Not all individuals survive to adulthood.

12. 6. Selection
The individuals with the best traits/adaptations will survive and have the opportunity to pass on it’s traits to offspring.
Natural selection acts on the phenotype, not the genotype!
Ex: when a predator finds its prey, it is due to the prey’s physical characteristics, like color or slow speed, not the alleles (BB, Bb)

13. Individuals with traits that are not well suited to their environment either die or leave few offspring.
Evolution occurs when good traits build up in a population over many generations and bad traits are eliminated by the death of the individuals.

18. Peppered Moth A Which moth will the bird catch? B Pocket Mouse

19. 7. Evidence for Evolution
Fossil record
Homologous body structures
Vestigial organs
Embryology
Biochemical evidence

20. a. Fossil record
Use of fossils to record the history of life on Earth.

21. Archaeopteryx
Missing link between reptiles and birds

22. B. Homologous body structures
Similar anatomy in different types of animals because of common ancestor.

23. C. Vestigial organs
“Leftover” traces of evolution that serve no purpose.

24. d. Embryology
Embryos of all vertebrates are very similar early on

26. E. Biochemical
DNA with more similar sequences suggest species are more closely related
Humans and chimpanzees share more than 98% of identical DNA sequences.