14.1    Early Evolutionary Hypotheses

	Evolution is a change in population over time.
	Larmarck's 3rd hypothesis was once a structure is modified by use or disuse, the modification is inherited by the organism's offspring.
	Weisman proved Larmarck's idea was incorrect by cutting off tails of mice and observing their offspring produce normal tails.

14.2    Darwin's Voyage

As Darwin's ship moved down the coast of South America, he saw gradual differences among animals and plants.

14.3    Darwin's Theory

	Farmers and other breeders raised more desirable offspring by selecting parents with more desirable characteristics (selective breeding)
	Theory of Natural Selection: Variation within population. Variations are favorable. More young are produced than can survive. Survivors are those with favorable variations and can reproduce. Small changes occur and populations change.
	Darwin's theory is called " the survival of the fittest."

14.4    Mechanism of Natural Selection

	New variations come from 2 sources:
	Homeobox genes are mutation genes that can produce major structural changes.
	Population niche is defined by its way of life and use of environment.
	Fierce competition arises, when 2 populations attempt to occupy the same niche.
	During England's industrialization, soot and smoke from factories blackened trees.
	Light-colored moths became black being less visible to birds and lived to reproduce.
	Normal distribution is when many characteristics of organisms form graphs with a bell-like shape.
	In directional selection, environmental conditions favor individuals at one extreme of the normal distribution.
	Selection against the most common variation is called disruptive selection.
	Stabilizing selection favors individuals with average phenotypes, reducing the number of individuals at the extreme.

14.5    Population Genetics

	Population genetics is the study of all genetic traits in a population.
	Gene pool is the combined genetic makeup of all members of a population.
	Modern science defines biological evolution as a change in allele frequencies within a population.
	Genetic drift is an accidental change in gene frequency.

14.6    Speciation

	A species is an interbreeding population of organisms that can produce healthy, fertile offspring.
	Adaptive radiation is multiple branching of a family tree.
	Convergent evolution is when different types of organisms evolve similar characteristics.

Back to course outline