1. Evolution
Chapters 15, 16, 17

2. Definitions of Evolution
Organic Evolution- gradual change in species over time
Geologic Evolution- evolution of the earth

3. Fossils Trace of an organism preserved by natural processes
Compare fossils with today’s species to study evolution
Generally skeletons are fossilized
Sedimentary rock forms layers as water deposits sediments so that the oldest layers are on the bottom and the newer layers are on the top- this gives scientists a fossil record

4. Fossils (continued)
Scientists use C-14 and U-238 to date fossils and rocks
Geologic Time Scale-
Earth’s history is divided into eras
Certain organisms lived in each era
First organisms were prokaryotic and marine
There are many missing links
Many fossils are of extinct species
Less than 1% of all species that ever lived exist today
There are times in the geologic time scale where many species became extinct at once (dinosaurs)

5. Living Organisms
Comparative Anatomy- study of similarities and differences among organisms
Homologous Structures- parts of different organisms that have similar structures but different functions (bird wing and human hand), these organisms are close evolutionarily
Analogous Structures- parts of different organisms that have a similar function but different structure (bird wing and insect wing), these organisms are not close evolutionarily

6. Living Organisms Homologous Structures Analogous Structures
Analogous Structures

7. Living Organisms (continued)
Vestigial Structures- serve little or no function in today’s organism but had a purpose at some time (appendix, tailbone)

8. Living Organisms (continued)
Embryological Similarities- if the embryos are similar, then the organisms have similar ancestors (human, chicken, pig)

9. Living Organisms (continued)
Biochemical Similarities- if the DNA structure is similar, then similar proteins are produced and the organisms have common ancestors
Family: Mustelidae
New Family: Mephitidae
“noxious gas”

10. Origins of Life Spontaneous Generation-
Living things arise from nonliving matter
This was a popular belief for thousands of years

11. Controlled Experiments- proved that Spontaneous Generation could not occur
Francesco Redi- (mid-1600’s)
Rotting meat in jars
Disproved spontaneous generation
Louis Pasteur- (mid- 1800’s)
Broth in flasks
Finally convinced people that spontaneous generation was wrong

12. Heterotroph Hypothesis
The modern hypothesis of the origin of life
The earth’s temperature was much higher 3.5 billion years ago
Gases were in different proportions (NO oxygen!!)
Organic compounds formed (protein substances)
These substances formed clumps which were inside a shell of water molecules
These clumps developed the ability to divide- the first heterotrophs
Eventually autotrophs developed (and thrived since there was competition for nutrients)
Availability of oxygen changed the earth’s conditions

13. Chemical Classification (4 min)

14. Modern Theories of Evolution- Lamarck’s Theory (1809)
Law of Use and Disuse-
The more an organism uses a part, the stronger it becomes
The less an organism uses a part, the weaker it becomes
Inheritance of Acquired Characteristics-
Characteristics acquired through use and disuse can be passed on to offspring
Example: Giraffes necks became elongated by stretching them to reach food

15. Modern Theories of Evolution- Lamarck’s Theory (1809)
This theory was disproved by Weissman. He cut the tails off 22 generations of mice! (ouch)
Out of 901offspring, not one had an abnormality

16. Darwin’s Theory of Evolution (1859)
Darwin sailed on the HMS Beagle as the ship’s naturalist
Sailed to Galapagos Islands off of the coast of Ecuador in the Pacific Ocean
Darwin observed that many species existed on the islands that also existed on the mainland but were slightly different
There were also differences from island to island among species

17. Darwin and Natural Selection (4min)

18. Darwin’s Theory of Evolution (continued)
Overproduction-
There are many more offspring produced than needed
A species population remains fairly constant over time
Many offspring do not reproduce
Competition-
Allows only a few offspring to reproduce

19. Darwin’s Theory of Evolution (continued)
Variation-
Individuals vary in characteristics (running, strength, disease resistance)
Some variations allow the individual to survive (getting food, escaping a predator)
Adaptations-
Organisms better adapted to their environment will survive and reproduce

20. Darwin’s Theory of Evolution (continued)
Natural Selection-
The environment selects which individuals survive since those better adapted to the environment survive and reproduce
These adaptations are passed on to the offspring
Survival of the fittest!!
Speciation-
Over time, the favorable adaptations become widespread in a population and the unfavorable ones disappear
When there are many changes, eventually a new species forms
Geographic isolation can lead to speciation

21. Whales Pakicetus (53 mil) Maiacetus inuus (47.5 mil)
Protocetids (25 mil)

22. Rate of Evolution Gradualism- Punctuated Equilibrium-
Evolution occurs slowly and continuously over time
Punctuated Equilibrium-
Species remains the same for thousands of years
Change occurs over a short period of time

23. Synthetic Rate of Evolution
Change in the allele frequency within a population over time
Populations evolve, not individuals!
Population genetics- the study of changes in the genetic make-up of populations
Gene pool-
The total of all alleles in a population
Each allele occurs within a certain frequency (1 in a 1,000; 1 in a 1,000,000)

24. Sources of Variation Mutation- Genetic Recombination- Migration-
Is rare for any one gene
If a mutation is helpful to a species, these organisms survive and reproduce and this allele becomes more frequent
Genetic Recombination-
Occurs in meiosis (crossing over) and at fertilization
Migration-
Brings different genes together
Effects small populations

25. Sources of Variation (continued)
Genetic Drift-
In a small population if some individuals have an allele that no other individuals have and they do not reproduce; those alleles are lost
Hardy-Weinberg Law- shows how rapidly evolution occurs in certain large populations

26. Adaptation
An inherited trait that improves chances of survival and reproduction
Camouflage- organism blends into the environment
Warning coloration- bright colors warn predators against eating the organism

27. Adaptations Mimicry- an organism mimics another organism’s coloration
Or coconut octopus

28. batesian mimicry examples

31. Natural Selection (3 Types)
Directional Selection-
An extreme phenotype becomes favorable
Occurs when the environment changes or a species migrates
Example is the giraffe’s long neck
Stabilizing Selection-
The average phenotype is favorable
Keeps allele frequencies constant
Disruptive Selection-
2 opposite phenotypes are favorable
Creates 2 subpopulations
May create 2 species

32. Types of Speciation Isolation- Adaptive Radiation-
Geographic- populations separated due to river, mountains, etc
Reproductive- populations can no longer interbreed
Adaptive Radiation-
Organisms of a species move (radiate) into different areas and adapt into their environment which leads to new species

33. Convergent Evolution Unrelated species develop similar characteristics
Example: insect wings and bird wings
Tasmanian devil and coyotes
Leads to analogous structures

34. Coevolution 2 or more species evolve in response to each other
Example 1: Bees and certain flowers open in the day
Example 2: Bats and certain flowers open at night

35. Examples of Natural Selection
Mosquitoes resistant to DDT
Bacteria resistant to a certain antibiotic
Light colored moths live in areas with light trees
Dark colored moths live in areas with dark trees