More Than An EyeWitness Evidence for Evolution

Sources of Evidence From the fossil record From studies of anatomy From studies of embryology From studies of DNA/biochemistry From observation

Transitional Organisms If evolution has occurred in the past there should be evidence of transitional organisms in the fossil record.

Archeopteryx Archeopteryx shows evidence of the evolution of birds from reptiles….there is evidence of feathers, a characteristic of birds, and claws, a characteristic of reptiles.

Identify how each organism uses its forelimb Frog Lizard Bat Human Cow Whale bird balance Walking flying Multiple uses walking swimming

Anatomical Studies show Homologous parts – similar in structure but not necessarily function – evidence of evolution from common ancestor

Anatomical studies show... Name two other organisms that have the ability to fly but have wings very different than those of the bird or the bat?

Analogous structures Butterflies or insects have wings but they are very different from the birds. These organisms do not have a common ancestor but have adapted to a similar environment. Again evolution explains the similarities.

Anatomical studies show Vestigial parts – why does a whale have a pelvis and femur bones if it has no hind limbs?

Vestigial structures Why does this salamander have eyes if it never sees the light of day?

Vestigial structures

Why do these structures occur? May be homologous to useful structures in other organisms and thus suggest evolution from an ancestor in which they do have a use.

Modification of anatomy The stinger of the wasp is not an entirely different structure but a modified ovipositor.

Anatomical Studies Anatomical studies of cells show a commonality in structure of the cell membrane among almost all living things. Does this suggest a common ancestor for all life?

Embryology Studies Even though it may not be apparent at this stage these three organisms are very different when born. Why do they look so similar now?

Embryology Studies The organisms are: Fish Bird Human Why would these three, so different looking organisms at birth, look so similar before birth?

Studies of Biochemistry/DNA Species Sequence of Amino Acids in the Same part of the Hemoglobin Molecule Human Lys-Glu-His-Iso Horse Arg-Lys-His-Lys Gorilla Lys-Glu-His-Lys Chimpanzee Lys—Glu-His-Iso Zebra Arg-Lys-His-Arg

Which organisms appear to be more closely related to each other? Human and chimpanzee have no differences in their amino acid sequence suggesting their close evolutionary relationship, they have a more recent common ancestor. Their DNA would be similar because DNA determines the sequence of amino acids in proteins.

Observations of Evolution in modern organisms Mosquitoes resistance to insecticides Bacteria resistance to antibiotics New strains of influenza viruses (?) New strains of malaria causing Plasmodium New strains of TB (tuberculosis) Peppered moth Darwin finches

Has and Does Evolution Occur? Scientists do not dispute that evolution does occur. Evolution is a FACT. How evolution occurs is not completely understood. Charles Darwin explained how evolution occurred through natural selection. Natural selection is a well documented THEORY uniting all of biology. Modern evolutionary theory uses ideas of genetics, particularly mutations, to help explain how evolution may occur. (Darwin didn’t know about mutations.)