of Evolution
What Did Darwin Explain in his Book, On the Origin of Species? He explained his theory of Evolution by Natural Selection He presented evidence that living species evolved from organisms that lived in the past The evidence comes from multiple fields of science
The Fossil Record Fossils are traces of organisms that lived in the past Can tell relative age of organisms (which came first) One can compare fossils of extinct organisms to living organisms to reveal patterns of gradual change Darwin noticed many “gaps”, but many new fossils have been found that fill some of these gaps. Conditions that create fossils are rare so we will never find fossils of every species that ever lived
Practice looking at the Fossil Record
Biogeography The study of the locations of organisms around the world Suggests that similar environments shape the evolution of organisms in similar ways
Embryology The study of the development of embryos One can compare the embryonic stages of different organisms to look for similar patterns and structures Similarities most likely derive from an ancestor that the species have in common
Which one is the rabbit?
Anatomy Scientists can compare the bodily structure of different species to find clues about how they are related Many internal similarities are best explained by evolution Homologous structures are characteristics that are similar in two or more species and that have been inherited from a common ancestor They don’t necessarily function similarly
What similarities do you see?
Color the common bone structures on the next page.
Anatomy Vestigial Structures A structure or organ is vestigial if it has diminished in size or usefulness in the course of evolution Vestigial structures are markers of evolutionary descent. For example, boa constrictors, which are descended from four-legged reptiles, grow tiny hind legs.
Top 10 Useless Limbs (and Other Vestigial Organs) 10 - The wings on flightless birds
Top 10 Useless Limbs (and Other Vestigial Organs) 9 - Hind leg bones on whales
Top 10 Useless Limbs (and Other Vestigial Organs) 8 - Erector Pili and Body Hair on Humans
Top 10 Useless Limbs (and Other Vestigial Organs) 7 - The Human Tailbone (Coccyx)
Top 10 Useless Limbs (and Other Vestigial Organs) 6 – Eyes of blind fish
Top 10 Useless Limbs (and Other Vestigial Organs) 5 – Wisdom teeth in humans
Top 10 Useless Limbs (and Other Vestigial Organs) 4 – The Sexual Organs of Dandelions
Top 10 Useless Limbs (and Other Vestigial Organs) 3 – Fake Sex in Virgin Whiptail Lizards (Vestigial Behavior)
Top 10 Useless Limbs (and Other Vestigial Organs) 2 – Male breast tissue and nipples
Top 10 Useless Limbs (and Other Vestigial Organs) 1 – The Human Appendix
Biochemistry A comparison of DNA sequences shows that some species are more genetically similar than others Similarities are evidence of hereditary relationships among species
Whale Evolution http://www.youtube.com/watch?v=I2C-3PjNGok