Evidences Behind Evolution What is Evolution Evolution the

Evidences Behind Evolution

What is Evolution? • Evolution: the changing of a population’s genotype (genetics) over time.

Evidences Behind Evolution • Fossils • DNA Sequence Analysis • Developmental Similarities • Anatomical Structures

Fossils • Fossils can tell us a lot about an organism • Using fossils, scientists can think about an organism’s age, location, and what the environment was like when the organism was alive • Fossils provide a record of evolution • The Fossil Record is not complete • No fossil evidence that contradicts evolution has ever been found

DNA Sequence Analysis • Because all living organisms share the same genetic code and use the same 20 amino acids, it has been possible to determine that organisms share a remarkable number of proteins that are similar to one another. • Due to mutations, the sequences of nucleotides change over time • Vestigial DNA: DNA that is no longer used but is in the genome

Developmental Similarities • Embryology: The process of animals being formed from an egg to an infant • Some organisms have similar structures in early stages of development • Notochords • Tails • Pharyngeal arches

Anatomical Structures • Homologous Structures • Homo = same • Structures that suggest a common evolutionary origin • i. e. Forelimbs of tetrapod vertebrates (four legged animals)

Anatomical Structures • Analogous Structures • Body parts of organisms that do not have a common evolutionary origin but are similar in function • Wings of birds vs. flies

Anatomical Structures • Vestigial Structures • A body structure in a present day organism that is no longer needed, or is used for a different function. • Wings on an ostrich or pelvis bones in whales