Evolution

Evolution Evolution, or change over time, is the process by which modern organisms have descended from ancient organisms.

Evidence of Evolution: Comparing Anatomy Fossil Evidence Anatomical Evidence Molecular Evidence Embryological

Evidence of Evolution Fossil Record Fossils that had formed in the different layers of rock were evidence of gradual change over time. One could view how a species had changed and produced different species over time.

Homologous Body Structures Homologous Structures: Structures that are made of similar bones but are different in form and function.

Analogous Structures Analogous structures perform similar functions, but are made of different structures. Example: The wing of an eagle & the wing of a insect have the same function (both enable the organism to fly) – but are constructed in different ways & from different materials.

Analogous Structures * While analogous structures do not indicate close evolutionary relationships, they do show that functionally similar features can evolve independently in similar environments.

Vestigial Structures Vestigial Structures are structures that are similar but are nonfunctional. Examples: 1. Snake Pelvis: The pelvis is the attachment point for legs and is therefore nonfunctional in an animal without legs

Vestigial Structures 2. Kiwi Wing: The wings of kiwis are too small to be of any use in flight 3. Human Appendix: Important for digestion in many mammals, but of limited use in humans & some apes

Molecular DNA and RNA All living organisms share the same genetic code Chromosome and gene similarities between species match evolutionary similarities This is true for both coding regions and “junk DNA”

Similarities in Early Development early stages of development, are similar, providing evidence that they shared a common ancestry.

The End