1. Evolution Overview Charles Darwin
Proposed the Theory of Evolution
Evolution-gradual change in a species through adaptations over time
Theory of Evolution= Natural Selection

2. Natural Selection
Natural selection is based on the following ideas:
natural variation
production of more offspring than can survive
competition for resources, and to escape predators
differential survival based on traits
Organisms with traits well suited to an environment are more likely to survive and produce more offspring than organisms without these favorable traits.

3. Evidence for Evolution
Evolution occurs over millions of years and cannot be seen in one lifetime
Scientists rely on evidence to support the Theory of Evolution

4. 1.) Adaptations
Adaptation- structure or behavior that helps an organism better survive in its environment.

5. Mimicry- a structural adaptation that enables one species to resemble another species.
Camouflage- a structural adaptation that allows a species to blend in with its surroundings

6. Physiological Adaptation- changes in an organism’s metabolism that occurs quickly. Many bacteria have become resistant to penicillin over the last 50 years

7. 2.) Fossil Record
Fossil-trace of a dead organism. Examples bones, dinosaur track, insects trapped in tree sap, impressions of leaves, animals buried in tar or ice
Give clues are to what ancient organisms looked like
Compare fossils to organisms we know today
Today’s species had to evolved from ancient species

9. 3.) Comparative Anatomy
Homolgous Structures- body structures on different organisms that are similar in structure or function and evolved from the same ancestor

10. Analogous Structures- Body structures on different organisms that are similar in function but did not evolve from the same ancestor.

11. Vestigial Structures- Body structure in an organism that no longer serves its original purpose but was useful to the ancestor

12. Embryo- earliest stage of growth and development of both plant and animals
Human embryos and embryos of all other vertebrates are very similar which suggests that all vertebrates are related

13. Nearly all organisms have DNA, ATP, and many of the same enzymes
The DNA of closely related organisms looks very similar

14. Natural Selection Occurs in populations over time not individuals
Population- all the members of a species that live in an area
Gene Pool- all of the alleles of the population’s genes

15. Genetic Equilibrium- the frequency of alleles remains the same over generations
Populations in genetic equilibrium are not changing so they are not evolving
Anything that changes the genes in the populations gene pool will cause evolution to occur

16. What Causes Changes in the Gene Pool?
1. Mutations that occur by chance or by radiation and chemicals
2. Genetic drift: frequency of alleles are changed by random events in an isolated population

17. 3. Gene flow: the transport of genes by traveling individuals
4. Non-random mating: Individuals selecting mates with specific heritable traits (sexual selection)
5. Natural selection

18. 3 Conditions of Natural Selection
Struggle for existence: more offspring are produced than can survive so organisms compete for survival
Natural variation among individuals
Survival of the fittest

19. 3 Types of Natural Selection
Stabilizing selection: favors average individuals in a population
Directional selection: favors one of the extreme variations of a trait
Disruptive/diversifying selection: favors individuals with either extreme of a trait

20. Speciation
Evolution of a new species that occurs when members of similar populations no longer breed with each other to produce fertile offspring

21. There are several reasons why similar populations no longer breed
Geographic isolation: when a physical barrier (lava from volcanic eruptions, sea level changes, etc.) divides a population

22. Reproductive isolation: occurs when organisms no longer breed with each other to produce fertile offspring because of
Differences in genes
Mating times change
Different numbers of chromosomes

23. How fast does speciation occur?
Gradualism: idea that species originate through a gradual change of adaptations (longer than 10,000 years)
Punctuated equilibrium: idea that species originate in rapid bursts (10,000 years or less) with long periods of genetic equilibrium in between

24. Two types of evolution
Divergent evolution (adaptive radiation): species that once were similar become increasingly different
Convergent evolution: distantly related organisms evolve similar traits