C. Common Ancestry predicts transitional fossils

C. Common Ancestry predicts transitional fossils

The late Devonian—no vertebrates on land yet

• http://web.ebscohost.com/ehost/external?hid=104&sid=2bc49599-c99c-47ef-83ac-108354959315%40sessionmgr113&vid=7

True tetrapod

True fish

D. LUCA

All living things have much in common, in their chemical composition, their germinal vesicles, their cellular structure,

and their laws of growth and reproduction… Therefore I should infer… that probably all the organic beings which have

ever lived on this earth have descended from some one primordial form, into which life was first breathed (Darwin,

1859, pg. 484, “On the Origin of Species”)

Morphology??

1970’s-Discovery of the “Archaebacteria” (extremophiles)1990’s-Discovered they were distantly related to “Bacteria”

Renamed them the Archaea

LUCA

The tree of life began to look like this in 1977: 1 gene (ribosomal)

Carl Woese

LUCA

Modern Genetics (late 1990’s and 2000’s): Many genes

Web of lifeMaybe “LUCA” wasn’t a single species, but a community of species that shared genes

The “Web” of Life

Carl Woese-discoverer of the Archaea

A modern view of the TOL orWOL must includeLateral Gene Transfer (LGH)

What are these?

“The solar-powered sea slug” carries genes for photosynthesis in its nuclear genome; these genes operate with the chloroplasts that it steals

• “There is a natural impulse for evolutionists to circle their wagons in making common cause against the creationists. I think we should resist it. Evolutionary theory itself evolves, but creationists attack it as a dogma of a revealed religion of which Darwin was the prophet, celebrating debate within the field as evidence for doctrinal weakness. In fact, it is evidence for disciplinary strength…”

• “I will argue that many of us have been defending a too- narrow form of neo-Darwinism, and that accepting a more pluralistic view of evolutionary pattern as well as evolutionary process will put us in a better position…”

• … a TOL might be the right idea within the three big lineages, but the WOL might be a better concept for early life

From Doolittle, Phil. Trans. R. Soc. B (2009) 364, 2221–2228