Evolution II 1

What is the evidence for evolution?(Chapter 21)

• Observations of evolution andArtifical selection

• Fossils

• Anatomic evidence

Question

Evolution II 2

Observations of evolution

Peppered moths-- Industrial melanism-- and its reversal

Evolution II 3

Other Examples

Corn ( ~ 9 K yrs )

Banana moths in Hawaii (1000 yrs)

Faroe Island house mouse (250 yrs)

Copapod of the Salton Sea, CA (30 yrs)

Drosophila paulistorum (a few yrs in a lab)

Evolution II 4

Paleontology

What does the fossil record show?Extinct life forms

Sequential appearance ofderived characteristics

Transitional forms

What are some limitations of the fossil record?

HabitatGeologic disruption Soft-bodied organisms

Ambulocetus natans (c. 50 Ma) – which means "walking whale that swims

Question

Evolution II 5

How are fossils dated?

Principle of “superposition”-- relative dating

Radioisotope dating (absolute dating)half-life14C 14N -- 5,730 years

(useful to ~ 60K yrs BP)

234U 230TH, ~ 80,000 years

40K 40Ar ~ 1.3 Billion yrs

Question

Evolution II 6

Anatomical evidence

What type of evidence doesanatomy reveal?

Derived traits have similar anatomy“homologous structures”

But “Convergent evolution’ occursindependent evolution“analogous structures”

Why does this occur?

Distinguishing homologous andanalogous traits is not always easy

A platypus has fur, a bill, webbed feet, and lays eggs

Question

Evolution II 7

Anatomical Evidence, con’t.

What does this mean:“Ontogeny reciprocates Phylogeny”?

Ernst Haekel’s original datais somewhat flawed

What are vestigial structures?

What are vestigial genes?-- gene for stripes in horses-- genes for teeth in birds

See Wikipedia for other cool exampleshttp://en.wikipedia.org/wiki/Vestigial

Human coccyx

Evolution II 8

Anatomical Evidence, con’t.

Intelligent design – not!

Human pelvis

External Testis

Eye?

Why?

Human coccyx