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Biology - Chapter 14 - Evolution: A History and a Process
Darwin developed a theorj of evolution
Ideas from Darwin’s Time
Terms: adaptation
acquired characteristics
evolution
descent with modification
natural selection
The Voyage of the Beagle
Darwin’s Observations
Ideas from Geology
Darwin’s Theory
Darwin’s Two Main Points
Descent with modification
Natural Selection
1. species
2. variation
3. adaptation
4. evolution
5. population
6. fitness
7. mutations
8. survival of the fittest
9. allele frequency
10. acquired characteristics
11. biosphere
12. gene pool
13. speciation
14. artificial selection
15. natural selection
16. Lamarck’s theory
17. Darwin’s theory
18. gradualism
19. Malthus
20. Lamarck
21. LyeI1
22. Darwin
23. Wallace
24. evidence of evolution
25. fossils
26. comparative anatomy (including homologous structures
27. vestigial structm’es
28. comparative biochemistry
Lamarck-1809 influenced Darwin
1. Organisms constantly strive to improve themselves
2. Most used body structures develop
Unused structures waste away (The Use/Disuse Theory)
3. The inheritance of acquired characteristics
¯ once a structure is modified by use/disuse
® the modification is inherited by the organism’s offspring
DispIooved
Darwin -1859 - wrote the Origin of Species
Natural Selection
1. There is variation within a population
2. Some variations are favorable
3. Not all young produced in each generation can survive
4. Individuals that survive and reproduce are the individuals
with the favorable variations
G~neraIIy accepted
Lyell - Geologist The Earth is very old
Malthus - Economist - There are only so many resources and
when they are used up times change.
Variation and Adaptation
During sexual reproduction alleles recombine causing
variation
Ways alleles recombine
1. Independent assortment of chromosomes
2. Crossing over during meiosis
3. Combination of genes from egg and sperm during
fertilization
Artificial selection - breeders selecting for a specific trait
Inbreeding - breeding very closely related organisms to
select for a trait
Outbreeding- breeding distantly related organisms to
increase variety.
Gradualism vs. Punctuated Equilibrium
Darwins idea
Gould - 1972
"populations remain genetically stable for long periods of
time, interrupted by brief periods of rapid genetic change"
caused by:
® sudden changes in the environment
® increased mutation rate
Divergent Evolution- isolated populations of a species evolve
independently
Examples - polar bears and brown bears
Convergent evolution- Occurs when natural selection has
produced similar adaptations in response to similar
environments.
Examples - Placentals and Marsuipalsconvergent evolution Google Search