The Evidence for Evolution

1. The Evidence for Evolution The many forms of evidence that convinced Darwin of the evolution of species and enabled him to formulate his theory.

2. Biogeography • The observed geographic patterns of distribution of species

3. Biogeography • Closely related but different • The birds have acommon ancestor on the mainland, but after becoming geographically isolated on islands developed adaptations to suit the differing environments of the islands.

4. Biogeography • Distantly related but similar • Distantly related rodents, that live in similar environments have developed similar body types

5. Darwin’s Hypotheses He realized the patterns he had observed regarding the distribution of species, both living and extinct, were evidence that species might have evolved. He hypothesized that remote oceanic islands became populated by species that arrived by water or air. After the species became established, many evolved into new species over time.

6. Darwin’s Hypotheses

7. Testing Darwin’s Hypotheses • To date, Darwin’s hypotheses have been supported by the observations of life on all remote islands. • For example, looking at Hawaii: • No native amphibians or mammals (exception of bat and sea lion) • Unique plants, birds and insects • No native terrestrial reptiles

8. Testing Darwin’s Hypotheses • With your table partner or groups of 3, read the textbook handouts provided. • Sections: Homologous and Analogous Features, Vestigial Features and Anatomical Oddities and Competition within Populations • Each student make a summary of one of the sections and share it with their group mates. • Answer the questions in section 7.4 #’s 1-8

9. Next day: The Origin of Species In his book, Darwin made two main points. • All species of organisms living on Earth today are descended from ancestral species. In other words, species evolve over time. • The mechanism that causes species to change over time is natural selection.