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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) * * 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>. * “Evolution 101.” California Museum of Paleontology. Web. 22 Nov. 2011 <http://evolution.berkely.edu/evolibrary/article/evo_01>. * Gingerich, Philip. “Fossils and the Origins of Whales. “ actionbioscience.org. Interview. Dec 2006. Web <http://www.actionbioscience.org/evolution/gingerich.html>. * 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>. * “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>. * “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>. * Wilkins, John. "Macroevolution, Its Definition, Philosophy and History." TalkOrigins Archive. (2006): n. page. Web. 23 Nov. 2011. <http://www.talkorigins.org/faqs/macroevolution.html>.