Ch 16.3 (Pg. 460-464): Darwin Presents His Case

Darwin and Alfred Russel Wallace Alfred Russel Wallace was a naturalist working in Malaysia, who also had similar ideas about evolution In 1858 Darwin and Wallace co- presented their theory to the Linnaean Society of London In 1859 Darwin published his book, On the Origin of Species

Darwin’s Case for Evolution Struggle for Existence More individuals are produced than can survive, and must compete with each other Variation and Adaptation Some variations are better suited to the environment than others Inherited variations that increase an organism’s ability to survive and reproduce are adaptations

Darwin’s Case for Evolution “Survival of the Fittest” Differences in adaptations affect an individual’s survival Organisms that are best adapted to their environment survive and reproduce better than others, and have the highest fitness

Darwin’s Case for Evolution Natural Selection Occurs when: More individuals are born than can survive There is natural heritable variation There is unequal fitness between individuals

Descent with Modification Means that all organisms are descended from a common ancestor Many generations must pass on traits with slight modifications to create new species