Evidence for Evolution

I. Evidence for Evolution

A. Fossils B. Molecular EvidenceC. Homologous structuresD. Vestigial structuresE. MimicryF. Camouflage

A . Fossils

1. Shows that life is old and has changed over time

2. Illustrates evolutionary change over past 4 billion years

Fossils

B. Molecular Evidence for Evolution

                     

1. When comparing DNA or amino acid sequences, the species with the most similar DNA are most closely related.

2. Number of Differences in Partial Hemoglobin DNA Sequences

Frog Chicken Goat Cow Chimp Human

Frog - 13 10 10 10 10

Chicken - - 6 7 5 5

Goat - - - 1 1 1

Cow - - - - 2 2

Chimp - - - - - 0

Human - - - - - -

2. Number of Differences in Partial Hemoglobin DNA Sequences Cont.

a. Humans are most closely related to chimpanzees • differences in hemoglobin DNA sequence

__0__

b. Humans are least related to frogs• differences in hemoglobin DNA sequence

• 10

C . Homologous Structures

1. Same structure in different organisms that may have evolved to have different functions.

2. They all have the same structure from a common ancestor.

3. Examplea. Same types of bones

• Humerus (upper arm)• Radius (lower arm)• Ulna (lower arm)• Carpals (wrist)• Metacarpals (hand)• Phalanges (fingers)

b.

C.

4. . Analogous Structuresa. Have the same function but not the same structure and did

not evolve from a common ancestor.

• Organisms that live in the same environment may evolve similar adaptations

• Organisms with similar adaptations may evolve from different ancestors

b. Examples:• Sharks and Dolphins• Wings (birds, bats, butterflies)

4. Analogous Structures Cont.

Sharks and dolphins are NOT closely related(Dolphins are more closely related to humans than sharks)

Evolved similar adaptations because they live in a similar environment

Analogous Structuresb. Wings of butterflies, bats, and birds have same function – flight.

Evolved the ability to fly from different ancestors.

• Are structures that were used in a common ancestor, but are disappearing over time in current species because they are no longer needed

• Examples: • Appendix in humans• Wisdom teeth in humans• Hip bone in whales

D. Vestigial structures

E. Mimicry -

1. Looking like another species that may pose a threat to predators

2. Examples:

Mimicry Examples a.

Coral Snake - Venomous King Snake – not venomous

Mimicry Examples b. Monarch and Viceroy

Monarch Butterfly (poisonous) and Viceroy Butterfly (not poisonous)

F. Camouflage -

1. Looking similar to the environment to avoid predators

2. Examples:

Camouflage Example a.

Camouflage Example b. Bird

Camouflage Example c. Frog

Camouflage Example d. Walking stick

Camouflage Example e. Praying Mantis

Camouflage