chapter22 - BIOL 1020 CHAPTER 22 LECTURE NOTES Chapter 22:...

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BIOL 1020 – CHAPTER 22 LECTURE NOTES Chapter 22: Evolution I. Historical perspective – ideas on evolution and related topics up to Darwin A. divine design and perfection model 1. espoused by Aristotle, the ancient Greek philosopher (284-322 B.C.) whose ideas on biology dominated most thinking on the subject until the renaissance 2. species were viewed on a scale from simple to complex 3. all organisms were seen as moving toward perfection (which was associated with complexity) 4. based on divine intervention and design (thus supernatural, outside the true realm of science) 5. now discredited in biology, but still part of the social consciousness B. fossils 1. fossils were known for centuries before Darwin 2. fossils reveal organisms unlike any living today, and the idea that some fossils represent species that had become extinct was recognized even by Leonardo da Vinci (1452-1519) C. acquired traits 1. mostly associated with Lamarck (1744-1829) 2. still focused on a model of organisms driven toward complexity, but involved an explanation with natural causes 3. postulated that changes or “acquired characteristics” during an organism’s life could be passed on to offspring 4. famous example was Lamarck’s model for how giraffes developed long necks – he claimed that stretching of the neck in one generation would lead to offspring with longer necks 5. understanding of genetic inheritance has led to rejection of acquired traits models D. birth of modern geology – Lyell, uniformitarianism , and the ancient Earth 1. prior to the early 1800s, the world view of most was that the Earth is very young (around 6000 years old) 2. in the early 1800s, geologists began to apply scientific reasoning to studies of geological processes, and quickly recognized that these processes require that the Earth be very old (billions of years) to occur naturally 3. this “ uniformitarian ” model of geological processes was made famous by Lyell’s Principles of Geology , which influenced Charles Darwin 4. the uniformitarian model is essentially the basis of geology today; confirming tests of this model include dating rocks using radioisotope ratios (more on that later) E. artificial selection 1. it was well known that domesticated animals and plants had been breed over centuries by humans to produce different varieties, indicating that the characteristics of a species can be modified by selection 2. some examples are different breeds of dogs and the “wild cabbage” lineage of cabbage, broccoli, cauliflower, Brussels sprouts, collards, kale, etc. F. population limits that would allow selection to act naturally were recognized 1. Malthus (1766-1834) wrote the most influential works on this subject 2. mathematically, populations will grow geometrically if unchecked 3. food supplies rarely can be expected to grow faster than arithmetically, thus putting a limit on population growth II. Darwin’s voyage A. Charles Darwin (1809-1882) received a degree in theology, but also was trained in the type of field biology common in
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This note was uploaded on 12/05/2011 for the course BIOL 1020 taught by Professor Dute during the Fall '06 term at Auburn University.

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chapter22 - BIOL 1020 CHAPTER 22 LECTURE NOTES Chapter 22:...

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