Bio Studyguide - Chapter 2 What Is The Evidence For...

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Chapter 2 – What Is The Evidence For Evolution On Earth? 1. Again, Mayr argues that evolution is no longer just a theory. a. Beginning with Darwin, more and more facts and evidence was discovered that it could no longer be called a theory b. After 1859, all scientists accepted evolution 2. Evolution as a historical process tested mainly by inference. a. Evolution must be inferred from observations and such inferences must be tested again and again against new observations and the original inference is either falsified or strengthened when confirmed by these tests. Most inferences made by evolutionists have by now been tested successfully and so often are accepted as certainties 3. Evidence for evolution: a. Evidence is now overwhelming. It is presented in great detail by Futuyma, Ridley, and Strickberger and also in anticreationist volumes 4. Fossil record…what is nature of this evidence? What are limitations of this evidence? a. The most convincing evidence of evolution b. Some of the remnants of the biota that lived at a given geological period in the past are embedded in the fossils in the strata laid down at that period; fossils found in most recent strata are often similar to living species or even identical. c. The older the strata (the father back in time) the fossil is the more different the fossil will be from living representatives d. Darwin said this was because the earlier strata had gradually evolved into their descendents more recent strata e. Paleontologists finds gaps in about every phyletic series (fossils are not a gradual steady change). There are documenting jumps (saltations) from type of organism to a different type f. Darwin said this is because there is incompleteness to fossil record since only a small fraction of organisms are preserved as fossils (because the dead are eaten or decay) g. Fossil-bearing strata were on plates that were subsequently subducted and destroyed in the process of plate tectonics and others were strongly folded and compressed obliterating the fossils h. They become fossilized only if right after death they are buried by sediment or volcanic ash. Even being caught in a flooding river and getting covered by mud (very rare event) i. Fossils that fill a large gap are known as missing links j. Erosion has destroyed fossils that occur in a specific geological horizon k. Fossils also may be buried thousands of feet underground l. Fossils are crucial to provide evidence for evolution 5. Homologous characters…what are they and why are they evidence for evolution? a. The study of phylogeny is really the study of homologous characters
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b. Since all members of a taxon must consist of the descendants of the nearest common ancestor, this common descent can be inferred only by the study of their homologous character c. Homologous is: a feature in two or more taxa is homologous when it is derived from the same (or corresponding) feature of their nearest common ancestor d. This definition applies to structural (position in relation to neighboring
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This note was uploaded on 02/02/2011 for the course BIO 120 taught by Professor Staff during the Winter '08 term at University of Michigan.

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Bio Studyguide - Chapter 2 What Is The Evidence For...

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