Chapter 23 Lecture Outline

Chapter 23 Lecture Outline - Biology 100 Vandan Desai...

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Biology 100 Vandan Desai Chapter 23: Evolution by &atural Selection (Lecture Outline) -------------------------------------------------------------------------------------------------------------------------- I. Charles Darwin’s Theory of Evolution A. Darwin publishes his observations and conclusion in On the Origin of Species in 1859 and challenges the theory of special creation B. Evolution i. Species today descended from preexisting species ii. Species are not static ; they change over time C. Darwin’s Observations —similar yet distinct species coexist in geographic proximity D. Darwin’s Conclusions —similar species descended from a common ancestor E. Researchers since Darwin have used a variety of approaches to gather evidence in support of Darwin’s theories II. The Pattern of Evolution: Have Species Changed through Time? A. Evidence That Species Have Changed through Time i. The fossil record was initially organized based on the relative age of the fossils 1. A fossil is any trace (bones, branches, shells, tracks, etc.) of an organism that lives in the past 2. Fossils can be dated based on the age of the sedimentary rock in which they are found ii. Began naming different periods of geologic time , creating the sequence of eons, epochs, and periods called the geologic time scale 1. Used radiometric dating techniques to assign absolute ages to geologic time scale 2. Earth is about 4.6 billion years old and earliest sign of rock formation is about 3.85 billion years ago (instead of 6000 years old) iii. As the fossil record has expanded, more evidence for evolution has emerged 1. Extinction a. Many fossils don’t resemble any known living plants/animals b. As more examples were unearthed, biologists concluded that
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This note was uploaded on 03/08/2010 for the course BIOL 100 taught by Professor Staff during the Fall '07 term at UMBC.

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Chapter 23 Lecture Outline - Biology 100 Vandan Desai...

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