volitans, aka the Earwing, uses its large ears to fly
EYES HAVE IT
CASE STUDY IN
EVOLUTION NO. 5
Written by Harold
White 9/93, Revised most recently April 2013
EVOLUTION, SPRING 2013
Page 3: Molecular Evolution
the Spirit of Snouters
Most evolutionists and
paleontologists now agree that
a large asteroid hit the earth near the Yucatan Peninsula about 65
years ago (33-35).
The impact created a huge crater and the resulting blast initiated a
atmospheric crisis that apparently doomed the dinosaurs and many other
taxa to extinction. [Please view
the 33 min on-line video, The Day the
Mesozoic Died] A few insignificant mammals survived. They evolved
and speciated to occupy the ecological niches vacated during the mass
A tremendous diversity of forms arose from this radiation. Dinosaurs
still rule the world and likely humans never would have evolved without
this astronomical disaster. This scenario has led fanciful biologists
minds like Dr. Seuss to contemplate the evolutionary consequences of
similar asteroid encounter. In this genre, although not following an
impact, the German zoologist Harald Stumpke created an imaginary island
populated with organisms known as snouters
(36, a French
that evolved and diverged from an single founding species.
now in this course, you have studied a variety of examples of
evolution and appreciate major aspects of evolution at the molecular
The following assignment asks you to use your imagination to create a
senario in adaptive molecular evolution.
Based on what we know
about the relationships among dinosaurs,
crocodillians, and birds, it is quite likely that dinosaurs posessed a
lactate dehydrogenase B that served double duty as an
in the dinosaur crystalline lens. Assume that the asteroid impact of 65
million years ago did not occur and that dinosaurs survived to the
day. Also assume that early on in this mythical lineage of dinosaurs
was duplication in the gene for LDH-B/epsilon-crystallin. Using
patterns in molecular evolution and what you have learned about lactate
dehydrogenase and crystallins, imagine the long-term evolutionary
of selection on paralogous LDH-B and epsilon-crystallin. Describe the
in both genes and protein products you would expect as the result of
selective forces that would be present.
to Page 1- Visualizing Lactate Dehydrogenase
to Page 2 - Corrective Lenses
L. W., Alvaerez, W., Asaro, F, and Michel, H. V. (1980)
Cause for the Cretaceous-Tertiary Extinction. Science 208, 1095-1108.
34. Kerr, R. (1992)
Impact Tied to Mass Extinction. Science 257, 878-880.
35. Sheehan, P. M.,
D. E., Hoffmann, R. G., Berghaus, C. B. and Gabreil, D. L. (1991)
Extinction of the Dinosaurs: Latest Cretaceous, Upper Great Plains, U.
S. A. Science 254, 835-839.
36. Harald Stumpke "Bau
und Leben der Rhinogradentia", THE SNOUTERS Form and Life of the
Translated 1967 by Leigh Chadwick with an Epilogue by Gerolf Steiner.
of Chicago Press.
Home Page, CHEM-667
or Hal White's Home Page,
Created 1 November
2000. Last updated 6 April 2013 by Hal White
Copyright 2013, Harold B.
White, Department of Chemistry and Biochemistry, University of
Newark, DE 19716