Evidence For Evolution

Evidence Fossil Record Anatomical Homology Developmental Homology Molecular Homology Biogeography

Fossil Evidence Provides snapshots of the past that, when assembled, illustrate a picture of evolutionary change There are gaps or missing pieces of the puzzle but inferences show that life is old and has changed over time.

Fossil Evidence Transitional fossils are fossils that show intermediate or in-between states of an organisms lineage.

Homology Similar traits or functions among organisms that show relationship. Three types Anatomical Developmental Molecular

Anatomical Homology Comparisons of the anatomy of two organisms can show relationship.

Anatomical Homology Sometimes a bone is present in an organism that has been reduced in size and either has no use or less importance than they do in related organisms. These are called vestigial structures.

Developmental Homology Similarities between the developments of embryos in organisms.

Developmental Homology Homeobox (Hox genes) are a sequence of nucleotides that are believed to control genes that influence body plans of organisms. They are believed to play an important role in evolution because mutations that occur in this gene lead to development of a body structure in a different position.

Molecular Homology Cellular – all organisms are made of cells that contain similar structures and are made of the same biomolecules

Molecular Homology Comparison of the amino acid sequence in related organism can show relationship.

Molecular Homology A more accurate reflection of evolutionary relationship lies in the nucleotide sequence rather than the amino acid differences because some proteins can evolve more quickly.

Biogeography Distribution of living things on the earth provides information about past life and the surface of the earth. Consistent with the movement of the earth’s plates.

Biogeography Example – marsupials are found in the Americas as well as Australia and New Guinea; however, they did not swim across the Pacific.

Biogeography Fossils of marsupials have been found in South America and Australia. Scientists have demonstrated that there was once a large land mass called Gondwana. Marsupials took a “ride” on the continents as they moved to their current locations.