Download Macroevolution - Park University

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“Macroevolution and microevolution
are parts of a continuum that are
distinguished more by the scale of
time on which they are studied.
Macroevolution, generally speaking, is
what paleontologists study on time
scales of thousands to millions of
generations. Macroevolution is
evolution that happens on a grand
time scale and explores questions such
as the origin of major groups of plants
and animals, and the development of
novel innovations like sexual
reproduction. Microevolution is what
people can study in laboratories or in
the field from a few up to a thousand
generations. The evolutionary process
itself, though, is not even
microevolutionary—the process takes
place on a generation-to-generation
time scale.” Gingerich
Microevolution:
Microevolution is any evolutionary change below the level of species. It is a change within an
existing species or gene pool. There is ample evidence that microevolution does exist. A more
known example of it is the evolution of resistance, such as with HIV. Scientists have shown that
HIV strains have evolved resistance to antiviral medicines. There are four mechanisms of
microevolution: mutation, migration (gene flow), genetic drift, and natural selection. These can all
directly affect gene frequencies in a population and any combination of them can be responsible for
a change in a species. Scientists believe that microevolution could be directly linked to
macroevolutionary patterns.
Macroevolution:
Macroevolution is defined to be any evolutionary change at or above the level of species. In
other words, it is between-species evolution. Using beetles as an example, macroevolution would
not focus on an individual species, but rather on the diversity of the entire beetle clade.
Creationists argue that macroevolution cannot be proven as microevolution can and has been.
The mechanisms of macroevolution are the same as those of microevolution (mutation,
migration, genetic drift, and natural selection). They just happen on a grander scale when given
enough time to cause the changes. “Macroevolution is not different than microevolution; rather,
it is the accumulation of many microevolutionary changes.” Scientists studying macroevolution
tend to look for patterns such as stasis, character change, lineage-splitting (speciation), and
extinction. Biologists do not disbelieve that evolution occurs, they currently are trying to
understand and explain how it happens.
Summary There is much controversy surrounding the
term macroevolution and whether it can actually be
proven through the use of science. The first problem
that is encountered in this debate is the defining
difference between macro evolution and
microevolution. and microevolution
Nichole Hemmingsen
NS241 Philosophy & History of Science
Park University
Fall, 2011
“Modern
evolutionary
biology theory
rests on the
assumption that
macroevolution
ary patterns can
be explained in
large part by
microevolution
ary processes.”
Bégin and Roff
“Evolutiona
ry and
ecological
studies now
regularly
incorporate
serious
consideratio
ns of
history,
scale, and
hierarchy.”
Jablonski
Positive Evidence from field crickets in support
of microevolutoin processes to explain
macroevolutionary patterns.
To investigate and focus on the problems of unknown rate and
pattern of evolution, Bégin and Roff raised seven different species
of field crickets in the lab and genetic correlation matrices were
used to show a comparison in a phylogenic structure. Results from
this experiment showed that macroevolution can be predicted
qualitatively from the quantitative genetic theory. One negative
aspect of this study in support of the theory is that no more than
three species have been compared in a single study.
“Because the constraint hypothesis has been supported in several
plant and animal studies, it therefore appears that quantitative
genetic variation is generally important during morphological
evolution, and can be used to model macroevolutionary patterns.”
(Bégin and Roff)
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Bégin, Mattieu, and Derek Roff. “From Micro- to Macroevolution through Quantative Genetic
Variation: Positive Evidence from Field Crickets.” Evolution. 58.10 (2004): 2287-2304. Web 16 Nov.
2011. <http://www.jstor.org/stable/3449477>.
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“Evolution 101.” California Museum of Paleontology. Web. 22 Nov. 2011
<http://evolution.berkely.edu/evolibrary/article/evo_01>.
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Gingerich, Philip. “Fossils and the Origins of Whales. “ actionbioscience.org. Interview. Dec 2006.
Web <http://www.actionbioscience.org/evolution/gingerich.html>.
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Jablonski, David. “Micro- and Macroevolution: Scale and Hierarchy in Evolutionary Biology and
Paleobiology.” Paleobiology. 26.4 (2000): 15-52. Web. 18 Nov. 2011.
<http://www.jstor.org/stable/1571652>.
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“Micro vs Macro.” Know Evolution. American Association for the Advancement of Science. Web. 18
Nov. 2011.
<http://knowevolution.com/mag/index.php?option=com_content&view=article&id=27:ywing&catid=9:frontpage>.
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“The Scientific Controversy over Whether Microevolution can Account for Macroevolution.”
Center for Science and Culture/Discovery Institute. Web. 16 Nov. 2011.
<http://www.discovery.org/f/118>.
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Wilkins, John. "Macroevolution, Its Definition, Philosophy and History." TalkOrigins Archive. (2006):
n. page. Web. 23 Nov. 2011. <http://www.talkorigins.org/faqs/macroevolution.html>.