AP Biology, Chapter 22
Descent with Modification: a Darwinian View of Life

Summary
Introduction
	1. State the two major points that Charles Darwin made in The Origin of Species concerning 
	Earth's biota.
		a. Current organisms evolved from ancestral species
		b. Natural selection is a mechanism for evolution

HISTORICAL CONTEXT FOR EVOLUTIONARY THEORY
	Introduction
	Western culture resisted evolutionary views of life
		2. Compare and contrast Plato's philosophy of idealism and Aristotle's scala naturae.
			a. Both ruled out evolution of organisms
			b. But for different reasons
				i. Plato: in the ideal, real world organisms are already perfect
				ii. Aristotle: each rung of the scale of complexity is occupied by an 
				organism already perfectly adapted for that position
		3. Describe Carolus Linnaeus's contribution to Darwin's theory of evolution.
			a. "Founded" taxonomy
			b. Grouped organisms hierarchically by shared physical traits
			c. Unintentionally created a system for identifying evolutionary kinship 	
		4. Describe Georges Cuvier's contribution to paleontology.
			a. Scientifically documented the fossils in the Parisian rockpile
			b. Concluded: the deeper, the older, the more different the fossils
			c. Recognized the extinction of species
		5. Explain how Cuvier and his followers used the concept of catastrophism to oppose the 
		theory of evolution.
			a. Averred catastrophes defined strata
			b. Said different organisms in overlying strata hadn't evolved but migrated 
	Theories of geological gradualism helped clear the path for evolutionary biologists
		6. Explain how the principle of gradualism and Charles Lyell's theory of uniformitarianism 
		influenced Darwin's ideas about evolution.
			a. Hutton: current gradual processes can explain land forms
			b. Lyell: gradual processes explain all geological changes in the past
			c. = the opposite of catastrophism
			d. Earth many millions of years old
			e. Darwin proposed evolution by gradual change in a constant environment
	Lamarck placed fossils in an evolutionary context
		7. Describe Jean Baptiste Lamarck's model for how adaptations evolve. Explain the 
		challenges to Lamarck's ideas with respect to current understandings of biology.
			a. Sentiments interieurs drives organisms to higher complexity
			b. Species change, become better adapted, by use and disuse
			c. Characteristics acquired by use and disuse are passed to offspring
	
THE DARWINIAN REVOLUTION
	Introduction
	Field research helped Darwin frame his view of life: science as a process
		8. Describe how Darwin used his observations from the voyage of the HMS Beagle to 
		formulate and support his theory of evolution.
			a. Found that organisms and fossils were adapted
			b. Related species on the Galapagos were adapted to local environments
			c. Hypothesized an old, constantly changing Earth
		9. Describe how Lyell and Alfred Russel Wallace influenced Darwin.
			a. Lyell: see #6; urged Darwin to publish
			b. Wallace: sent manuscript in 1858; matched Darwin's unpublished work
	The Origin of Species developed two main points: the occurrence of evolution and 
	natural selection as its mechanism
		10. Explain what Darwin meant by "descent with modification."
			a. All life originated from a single, unknown prototype
			b. Descendents spread and became adapted to new habitats
		11. Explain what evidence convinced Darwin that species change over time.
			a. Saw hierarchical taxonomy as phylogeny
		12. Describe the three inferences Darwin made from his observations that led him to 
		propose natural selection as a mechanism for evolutionary change.
			a. Exponential growth + limited resources  struggle for existence
			b. Variation in heritable traits  differential survival
			c. Small changes over generations  adaptation of populations
		13. Explain how an essay by the Rev. Thomas Malthus influenced Charles Darwin.
			a. Malthus, 1798, An Essay on the Principle of Population
			b. Populations grow exponentially, resources don't 
			c. Darwin incorporated that as differential survival
		14. Distinguish between artificial selection and natural selection.
			a. Artificial is human-directed selective breeding
			b. Natural is differential survival based in variability of useful traits 
		15. Explain why the population is the smallest unit that can evolve.
			a. Individuals are tested during their lifetime
			b. Populations record the results when they are gone
		16. Using some contemporary examples, explain how natural selection results in 
		evolutionary change.
			a. Galapagos finch beak shape changes in response to food change
			b. Antibiotic resistant bacteria predominate with overuse
			c. Transplanted guppy size increases in response to predator
	
EVIDENCE OF EVOLUTION
	Introduction
	Evidence of evolution pervades biology
		17. Explain how homologous structures support Darwin's theory of natural selection. 
		Explain how biogeography and the fossil record support the evolutionary deductions 
		based on homologies.
			a. Homologous structure: similarity inherited from a common ancestor
			b. Biogeography
				i. Relatedness of neighboring or once neighboring species
				ii. Darwin observed homologies distributed by geography
			c. Fossil record
				i. Lineages of major groups show acquisition and alteration of homology	
				ii. Sufficient transitional forms are present
	What is theoretical about the Darwinian view of life?
		18. Explain the problem with the statement that Darwinism is "just a theory." Distinguish 
		between the scientific and colloquial use of the word "theory."
			a. Evolution is based on a vast amount of historical evidence
			b. Commonly "theory" is used as scientists use "hypothesis"
			c. Darwin's proposed mechanism is theoretical