Evidence of Evolution

What is Evolution?

• The change of a species population over generations

What is Natural Selection?

• Organisms best suited to the environment reproduce more successfully

• Over generations, favorable traits increase in the population; unfavorable traits decrease

DARWIN

RESEARCH?

Survival ofThe Fittest

EVIDENCE?

Biochemistry/DNA

ComparativeEmbryology

ComparativeAnatomy

BiogeographyFossil Record

“CElia and FRed Bought CAndy Before Dinner”

CE – Comparative Embryology

FR – Fossil Record

Bg – Biogeography

CA – Comparative Anatomy

BD – Biochemistry/DNA

Dating of Fossils• Relative Dating

• Fossils in the lower layers of the Earth are older and less complex than fossils in the upper layers

• Absolute Dating

• Age is determined by measuring the amount of radioactive evidence • Carbon 12 versus Carbon 14 Half-life

Fossil Evidence

Biogeography

• Study and comparison of fossils and living organisms and where they are located (geographical distribution)

• Animals on islands look like others on the closest land mass rather than far away distances

Comparative Anatomy

• Homologous Structures

• Analogous Structures

• Vestigial Structures

• Embryonic Structures

Homologous Structures

• Same structure, but different function

• Originated from a common or shared ancestor

• Example: human and penguin arms

Homologous Structures

Very similar skeletal structures

Analogous Structures• Same functions, but different

structures

• Find a similar solutions to same problem

• Example: bird and bee wings

Analogous Structures• Both organisms

can hover to feed on flowers, but there is NO ANATOMICAL OR EMBRYOLOGICAL SIMILARITY between the wings.

• Their wings evolved independently and differently.

Vestigial Structures• Functionless structure that

occurs in present-day organisms, but had function in an ancient species

• Examples• Tailbone and appendix in

humans• Pelvic bone in whales and

snakes

Embryonic Development(Embryology)

• Similar structures are found in embryos of different species.

• This shows that they share a common ancestor.

Embryonic Development(Embryology)

• Each embryo had gill slits and a tail in the early stages of development

Biochemistry and DNA• In organisms, amino acid

sequences are very similar, BUT not exact.• Example – Hemoglobin

• The more similar the homologous proteins in different species, the more closely related

Patterns of Evolution

• Coevolution• The change in two or more species

in close association with each other• Example:

• Humming bird and the flower of the plant it feeds on

• Butterfly and the flower of the plant it feeds on

Coevolution

Patterns of Evolution• Convergent evolution

• Unrelated species can develop similar characteristics• Example: shark, penguin, and

porpoise share similar characteristics that suit their environment

• Long stream-lined body• Fins that match in appearance and

function

Convergent Evolution

Patterns of Evolution

• Divergent evolution• Two or more related populations

or species become more dissimilar over time (they adapt to their environment)• Example: finches have different

beaks due to different environments/food sources

Divergent Evolution