Transcript Darwin`s Other Mistake

Darwin’s Other Mistake
Michael R. Rose and Theodore Garland, Jr.
Darwin’s 1st Mistake
• Mechanism of heredity wrong
• Thought “ an arbitrary number
of ductile transmissible
gemmules” moved from
organs to gonads
• Gemmules allowed blending
along with inheriting acquired
characters
Darwin’s 2nd Mistake
• Evolution is gradual and occurs so
slowly that it cannot be observed
• 1896 Illinois Corn Experiment
selected for oil content showed
observable evolution
• Many more studies followed that
showed natural selection can be
observed
• But most people still believe
natural selection happens very
slowly and is difficult to observe
Charles Lyell
Experimental Evolution
• Definition: “Research in which
populations are studied across multiple
generations under defined and
reproducible conditions, whether in the
laboratory or in nature.”
• The key to keep biology as a fully
scientific field.
• More closely resembles physics that
most research in biology.
• Emphasizes hypothesis testing,
trajectories, replication and
reproducibility.
Macroevolution vs Microevolution
• Micro – evolution within
populations
• Macro – change at or above
the level of the species
• Speciation is on the fuzzy
boundary of both.
• Macro is difficult to observe
because of the time involved
but scientists use
microevolutionary analyses to
address hypotheses about
macro.
THE IMPORTANCE OF EXPERIMENTAL STUDIES IN
EVOLUTIONARY BIOLOGY
Douglas J. Futuyma and Albert F. Bennett
The major approaches to analyzing
evolutionary processes:
• Experimental Evolution
• Studies of Natural Populations
• Comparative methods
Experimental Evolution
• AdvantagesReplication and control.
• Disadvantages –suited
to laboratory rather
than to natural
situations.
Natural Populations
• Advantage- offer
ecological realism
• Disadvantage - lack of
ability to replicate
results and control
variables.
Comparative Methods
• Advantage- widely used
method to understand
evolution of characters
in the natural world.
• Disadvantage• Correlational
• Assumption of
parsimony
2 Examples of the Contribution of Experimental Studies
to understand Evolution
• Trade-offs- adaptive
• Genetic Drift – a founder
event (or bottleneck in
gain and correlated loss.
population size) may initiate new
• Escherichia Coli
paths of adaptive evolution.
• Drosophila pseudoobscura