Ch 22.2

Lived in England & fascinated with nature Went to school to became a physician Dropped out (disgusted by surgery) Became a clergyman Invited on the HMS Beagle Hydrographic survey of South America

Documented Kept a Journal: The Voyage of the Beagle Collected Thousands of plants, animals, & fossils

Thinks about the voyage, animal/plant collection, fossils, geology… Begins to describe the most revolutionary idea in biology Receives a letter from colleague Alfred Wallace with same idea They publish their idea together Then Darwin finishes his book

Galapagos islands, while close to each other, contained: Various ecosystems Organisms similar to, but different from each other Each had adaptations to fit the environment

1.For any species, population sizes would increase exponentially if all individuals born reproduce successfully 2.Populations tend to be stable in size, except for seasonal fluctuations 3.Resources are limited

Production of more individuals than the environment can support leads to a struggle for existence among individuals of a population, with only a fraction of their offspring surviving

4.Members of a population vary extensively in their characteristics 5.Much of this variation is heritable

Survival depends in part on inherited traits; individuals whose inherited traits give them a high probability of surviving and reproducing are likely to leave more offspring than other individuals

This unequal ability of individuals to survive and reproduce will lead to a gradual change in a population, with favorable characteristics accumulating over generations

Organisms better suited to the environment are more likely to survive & reproduce than organisms less suited to the environment Mutation  Variation  Selection

deos.html deos.html There is a grandeur in this view of life…

Artificial Selection: humans modify species over many generations by selecting and breeding individuals with desired traits

CabbageBrussels sprouts Kale KohlrabiWild mustard Broccoli Cauliflower

ml ml