1. EVOLUTION

3. What is Evolution?
Change in allele frequencies (the gene pool) over time in a population
Biological change on a timescale of generations
Individuals change, but only populations evolve

4. What does evolutionary theory explain?
Adaptations
Just about any feature on an organism is an adaptation – most of the things you think of
By definition: inherited features of organisms that fit life habits, allowing them to survive and reproduce
Biodiversity
The diversity and number of species on earth
All those living things on earth-- the whole “shootmatch”

5. Natural Selection a.k.a. “survival of the fittest”
Broken down into four parts

6. Natural Selection Individuals in a population vary in their traits
Some of these differences are heritable-they can be passed on from parent to offspring.

7. Natural Selection Many more offspring are produced than can survive
only some will survive long enough to reproduce, and some will produce more offspring than others- some will have a suite of traits that are going to allow them to reproduce

8. Natural Selection
Individuals with certain traits are more likely to survive and reproduce. Natural selection occurs when individuals with certain traits produce more offspring than do individuals without those traits

9. Main Idea:
Heritable variation leads to differential reproductive success; this is natural selection
Now, rewrite this statement in your own words.
Then work on the graphing activity on the back of your notes.

11. Ways to Create Evolution
1. Genetic drift - genes will vary (so change) in population from generation to generation

12. Ways to Create Evolution
2. Natural Selection – 3 “modes” (explained soon)

13. Ways to Create Evolution
3. Gene flow or gene migration – transfer of genes from one population to another (cross breeding)

14. Ways to Create Evolution
4. Mutation- in genes. This is where new traits come from.

15. Ways to Create Evolution
BONUS WAY (HUMAN CAUSED) -- Non-random mating (like purebred pet breeding)

16. Natural Selection Selection acts on individuals but populations evolve
Process in which more favorable traits survive through time
Selection acts on individuals but populations evolve

17. Modes of Natural Selection

18. Modes of Natural Selection
Directional
Diversifying
Stabilizing

19. Why does evolution take so long?
Rate of Reproduction
Life span
# of offspring
Growth rate
Length of reproduction cycle
Number of habitats
Size
External environmental forces
Earthquake, weather, etc.

20. Rate of Evolution Pressure to change Ability to change – diversity
Rate of reproduction – Remember what causes this from your previous notes!

21. Biological Diversity
Diversity is the single most important function of evolution
Reasons for diversity
Adapt to environmental changes
Respond to change Ex: pollution, global warming
Live in multiple habitats

22. Adaptation Natural selection can eventually lead to adaptation
Definition – characteristic or trait that improves the survival and reproduction of an individual or population
Adaptation is a GENETIC change

23. Acclimation
Definition – Temporarily improving survival and reproductive success
Characteristic or trait is NOT GENETIC and cannot be passed on

24. Types of Adaptation Models of evolution
Gradualism – Very slow adaptation
Punctuated Equilibrium – Rapid burst of change resulting in new species

25. Fossils Definition: A remnant or trace of a past organism
Many varieties of dating techniques are use to determine when the organisms became fossilized – ex: strata of rock it is found and radioisotope dating
Paleontologists are scientists that study fossils

27. Relationship Types Homologous structures – show a common ancestor
Structures are similar, but adapted to the new organism
Vestigial structures – structures that are present but have little to no functional value (odd traits link them)

28. Evolution does not result in perfect organisms
Selection edits existing variation (some survive, some don’t)
Compromise between adaptations
Historical constraints (like
earthquakes, volcanoes, etc)
Chance (some organisms are simply lucky)