Developing a Theory to Explain Change: further evidence of evolution

1. Pages 126 - 133 Developing a Theory to Explain Change: further evidence of evolution

2. Evidence of Evolution • 1. The fossil record • 2. Transitional fossils • 3. Patterns of distribution • 4. Anatomy • 5. Embryology • 6. Molecular biology • 7. Genetics

3. 1. THE FOSSIL RECORD :The evidence from paleontology • Paleontology is the study of fossils which can be defined a any sort of remains of once living organisms. • Paleontology includes entire bodies or parts of bodies (frozen mammoths) • Hard Parts – e.g., teeth, bones, horns.

4. Plant Fossils

5. Animal Fossils

6. Petrifaction, Imprints, Casts • Petrifaction: the tissues of the organism are replaced with minerals. • Imprints or Casts: soft bodied organisms are covered very fast and leave a cavity that may fill with minerals

7. Fossilization • Fossilization is a rare occurrence. • Usually the fossil record is dominated by organisms that were the most abundant and widespread. • The fossil record reveals a general increase in diversity and complexity of life over time. • The oldest fossils are usually found in the bottom strata and the youngest in the top strata.

8. Geological Strata

9. Transitional Fossils • The original fossil record gave “scattered snapshots” of ancestral forms. • On-going discoveries of hundreds of transitional fossils show intermediate links. Fossil Discovery in Kitchen Counter

10. Biogeography • Biogeography: the study of past and present geographical distribution of organisms. • Darwin and Wallace hypothesized that organisms evolve in one location and then spread out to other regions.

11. Biogeography: plate tectonics

12. Biogeography: continental drift Where did all the biodiversity in Madagascar come from?

13. Comparative Anatomy • Homologous structures: have similar structural elements and origin but may have a different function. • Analogous structures: perform similar functions, even though the organisms do not have a common evolutionary origin. Vestigial organs

14. Embryology • The embryonic development of many organisms shows striking uniformities. • Embryonic similarities are particularly obvious during cleavage, morphogenesis, and the early stages of differentiation in the embryo.

15. Molecular Biology: comparative biochemistry • The field of molecular biology has developed as technologies to identify molecules, such as DNA and protein molecules, has developed. • If two species have similar patterns in proteins of their DNA, this similarity indicates that these portions of their DNA were most likely inherited from a recent common ancestor

16. Genetics • The use of modern technologies has led to many discoveries that support Darwin’s theory. • The field of genetics has lead to understanding of how species pass on their traits to their offspring and how the blueprints for these traits can change by mutation. • Current evolutionary theory connects genetics with the theory of natural selection and how natural selection operates on populations. Genographic project