Scientific Colloquium
March 25, 2015, 3:30 p.m., Building 3 Auditorium
ALEXANDER
WERTH
HAMPDEN-SYDNEY COLLEGE
"Living
Fossils"
Charles Darwin first coined the
term “living fossil” to describe archaic forms, including
lungfishes and horseshoe crabs, which seem not to have changed
since their appearance in the fossil record hundreds of millions
of years ago. As Darwin explained, evolution is not merely a
chronicle of historical events but an ongoing process that is
the fundamental basis of all life on Earth. Given that evolution
is all about species changing over time, how can we explain such
species as the coelacanth, tuatara, or chambered nautilus, which
certainly appear to violate the central rule of constant change?
To what extent have these species truly stopped changing? Can we
best explain this phenomenon by internal (genetic) or external
(environmental) processes?
More broadly, what do “living fossils” tell us about species?
What is a species, and how do we recognize distinct species? Is
it possible to distinguish ancient species from recent species?
Can we connect them in a continuum over the grand sweep of deep
geologic time? Why is the modern species concept (based on
reproductive compatibility) problematic for paleontologists? Is
it worth fixing this problem or should we construct a new model
to define and distinguish species? Finally, what can “living
fossils” tell us about basic patterns and processes of life,
including what we might find in the extraterrestrial life of
other worlds?
About the Speaker:
Alexander J. Werth is Venable Professor of Biology at
Hampden-Sydney College in Virginia. He earned his BS in zoology
from Duke University (1985) and AM and PhD in organismic and
evolutionary biology from Harvard University (1987, 1992), then
was a postdoctoral fellow with the North Slope Borough (Alaska)
Department of Wildlife Management. He has been a Fulbright
Scholar with the Ministry of Fisheries, Agriculture, and Marine
Resources in the Republic of Maldives and a visiting scientist
at marine laboratories in Maine, Alaska, and Iceland.
His research focuses on two areas: 1) evolutionary complexity,
particularly why some features of organisms tend not to change
over time (e.g., vestiges, atavisms, “living fossils”); and 2)
biomechanics and functional morphology of feeding in toothed and
baleen whales, especially the material properties of the whale’s
oral filter and how flow and drag affect these dynamic
processes. He is working with international teams of biologists,
engineers, and physicists to construct and test 3D printed
models so that we can better understand the filter feeding of
whales and design more effective industrial filters.
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