Evidence for Evolution

1. Shania Didier Serre Evidence for Evolution

2. A fossilis a remnant or a trace of a one living thing. • Usually, it is the ‘hard parts’ of plants and animals that are preserved. E.g. wood, bones or shells. • The ‘softer parts’ are usually decayed or eaten. However, in rare cases, the remains of soft-bodies animals, such as jellyfish or bacteria have been preserved. • Fossils are often preserved by being covered by sediments. Some interesting fossils have also been preserved in amber or tar. 1. Fossils

3. Formation of fossils

4. Fossilsare usually found in sedimentary rocks. • The relative age of rocks can be found by assuming that younger sedimentary rocks are above older sedimentary rocks. • The oldestsedimentary rocks contain no fossils. • Fossil records are incomplete, as fossilisation is a rare event, and organisms with hard body parts are more likely to be fossilised than soft-bodied ones.

5. Transition fossils are fossils that appear to have characteristics of two different groups of organisms • Transition fossils document the evolution of ancient reptiles to mammals. • Two of the most famous transition fossils are archaeopteryx- which provides evidence for the common ancestry of birds and reptiles; and the lobe-fin fish, which indicates that amphibians may have evolved from fish. Transitional Forms

6. Biogeographyis the study of living things in relation to geographical regions. • DarwinandWallaceused biogeography as evidence of evolution. • They noticed that species living in the same area were more similar to each other than to species living in similar habitats far apart. This shows that species evolved due to the selective pressure in their own habitats. 2. Biogeography

7. Comparative Embryology compares the early development of embryosto show similarities to other organisms. • Similar genes from a common ancestor controls development. • As development progresses, different genes ‘turn on’, resulting in distinctive characteristics. 3. Comparative Embryology

8. Comparing the development of embryos of different species.

9. Comparative anatomy is the study of similarities and differencesin the anatomy of different species. • This helps us understand the adaptive changes they have undergone in the course of evolution from common ancestors. • There are three types- Homologous structures, Analogous structures, and Vestigial structures. 4. Comparative Anatomy

10. Same structures, but different functions. • Due to DNA from a common ancestor, some body parts have been modified for different functionsin different environment. E.g. whale flipper, bat wing, human arm. Homologous Structures

11. Different structures, but same functions. • They suggest how different animals can adapt to the environment in a similar way. E.g. bee’s wing, bird’s wind; (both for flight). Analogous Structures

12. They serve no functions, but have functions in other organisms. • Structures may not serve a purpose now, but did in the past. • Ancestral DNA still codes for these parts. E.g. whale leg bones, appendix, snake pelvis. Vestigial Structures

13. Scientists have found that DNA and the proteins it produces can provide evidence about evolution. • If 2 new species evolves from a common ancestor, their DNA and protein molecules slowly change and become different. • the differences in DNA or differences in specific proteins show relatedness. • When combined with fossil age- their lineage becomes clearer. 5. DNA Sequencing