Bio@Tech

Georgia Tech School of Biology

Summer 2012

What is Life?

Bio@Tech

Georgia Tech School of Biology

Summer 2012

What will happen if organisms reproduce, imperfectly, and the variation makes a

difference in survival and reproduction of the organism?

Bio@Tech

Georgia Tech School of Biology

Summer 2012

What will happen if organisms reproduce, imperfectly, and the variation makes a

difference in survival and reproduction of the organism?

School children modeled this by drawing copies of a drawing of animal. Then most of these copies were eliminated (disaster or climate change), and they

drew copies of the surviving drawings, for 6 successive generations. These drawings were

animated to produce this video: http://www.youtube.com/watch?v=N8X-j0dbZWs

Bio@Tech

Georgia Tech School of Biology

Summer 2012

Evolution is an inevitable consequence of life on Earth

• Heritable variation – mutation, recombination.

• Competition for limited resources.

• Natural selection.

• Time – many generations.

• Long-term environmental changes.

Bio@Tech

Georgia Tech School of Biology

Summer 2012

Hutton’s UnconformityRed sandstone (horizontal)

Grey shale (vertical)

“… no vestige of a beginning, no prospect of an end.”

–James Hutton

(photo: Anne Burgess)

http://en.wikipedia.org/wiki/Image:Siccar_Point.jpg

Bio@Tech

Georgia Tech School of Biology

Summer 2012

Homology of Mammalian Limbs

• Buffon (1707-1788) noted the homologous structure of mammal limbs and suggested descent from a common ancestor.

• Common structures in four very different mammals:– humerus (gray)– radius (orange)– ulna (beige)– carpals (yellow)– phalanges (brown)

Campbell & Reece, Fig. 22.14

Bio@Tech

Georgia Tech School of Biology

Summer 2012

Sean Carroll - http://www.hhmi.org/biointeractive/evolution/lectures.html

Bio@Tech

Georgia Tech School of Biology

Summer 2012

Sean Carroll - http://www.hhmi.org/biointeractive/evolution/lectures.html

Bio@Tech

Georgia Tech School of Biology

Summer 2012

What the fossil record shows

Foraminiferans – www.don-lindsay-archive.org/creation/foram_work.gif

Bio@Tech

Georgia Tech School of Biology

Summer 2012

Evolution of Horses

Bio@Tech

Georgia Tech School of Biology

Summer 2012

Horsetoes!

Bio@Tech

Georgia Tech School of Biology

Summer 2012

Darwin's Original Insights

• Descent with modification from a common ancestor – a tree describes genealogy of life

• Natural selection – the mechanism of evolution

Bio@Tech

Georgia Tech School of Biology

Summer 2012

Darwin's Tree Illustrations

1859 Origin of Species – only figure

1837 notebook page

Bio@Tech

Georgia Tech School of Biology

Summer 2012

Natural Selection and Time

Bio@Tech

Georgia Tech School of Biology

Summer 2012

Bio@Tech

Georgia Tech School of Biology

Summer 2012

Bio@Tech

Georgia Tech School of Biology

Summer 2012

How often does a black coat mutation arise?

Depends on:

Bio@Tech

Georgia Tech School of Biology

Summer 2012

How often can we expect a black rock pocket mouse to arise by mutation?

Mutation rate for black MCIR allele = 2 x 10-8

Bio@Tech

Georgia Tech School of Biology

Summer 2012

Bio@Tech

Georgia Tech School of Biology

Summer 2012

Bio@Tech

Georgia Tech School of Biology

Summer 2012

Bio@Tech

Georgia Tech School of Biology

Summer 2012

Bio@Tech

Georgia Tech School of Biology

Summer 2012

Bio@Tech

Georgia Tech School of Biology

Summer 2012

Bio@Tech

Georgia Tech School of Biology

Summer 2012

Bio@Tech

Georgia Tech School of Biology

Summer 2012

Evolutionary hypotheses are testable and falsifiable

• Discovery and characterization of new transitional fossils

• DNA sequence comparisons

• Radiometric and isotopic dating

• Geological record

• Astrophysics

Bio@Tech

Georgia Tech School of Biology

Summer 2012

Thomas Huxley's grandchildren

Bio@Tech

Georgia Tech School of Biology

Summer 2012

Modern Biology Is Evolutionary Biology

• “Nothing in biology makes sense except in the light of evolution.”

– Theodosius Dobzhansky

• “The alternative to thinking in evolutionary terms is not to think at all.”

– Peter Medawar, Nobel Laureate, 1960

Bio@Tech

Georgia Tech School of Biology

Summer 2012

Useful Websites• National Academy of Sciences: Teaching About

Evolution and the Nature of Science– A good overview of evolution and science.

• UC Museum of Paleontology– Info on the theory and history of evolution

• Talk Origins Archive– Info on evolution and creationism

• Talk Origins Archive FAQ– A good entry point to the Talk Origins Archive