Fossil formation Since we use fossils to help us explain evolution, how come we don’t find fossils of every organism? Why are there gaps in the fossil record?

Because they are most likely to form in… Wet lowlands Slow moving streams/rivers Shallow seas Volcanoes (near, not in!) Fossils form when the organism is rapidly covered with sediment or ash, which eventually becomes stone

Why wouldn’t a fossil form? Scavengers? Rate of decay? Not in one of the previous slide’s environments? Be able to explain…

Anatomy and Development Relationships between organisms can be determined by their anatomy (how they look) and their development(do they go through the same stages of development?) Terms to know: Vestigial structures Homologous structures Analogous structures

Vestigial Structures A structure in an organism that is reduced in size and function

The appendix

Homologous structures Anatomical structure that share a common ancestry (they look the same and do the same thing)

Analogous structures Structure of different species having similar function but not from the same evolutionary origin

Proteins and DNA If changes occur in an animals body, we should also find changes in their proteins and DNA. The more similar two organisms amino acid sequence, the more closely related they are. The more the amino acid sequence differs, the less related they are

Natural Selection The process by which individuals that have favorable variations and are better adapted to their environment survive and reproduce more successful than less well adapted individuals Ex: the TB bacterium (p. 289) and Darwin’s finches (p. 290)