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Unformatted text preview: Exam 1 Study Guide Lecture 2: Chapters 22 and 24Evolution Revisited The Darwinian Revolution o Charles Darwin and the voyage of the HMS Beagle Lasted from 1831-1836; Darwin was only 22 at the time Darwins scientific collections and observations led to On the Origin of Species (1859). Darwins finches o What is evolution? Evolution is the change in genetic composition of a species over time, such that species alive today are the descendants of ancestral species. o What ideas came out of Darwins voyages? Descent with modification: species evolve and change over time. Adaptations: characteristics that enhance organism survival and reproduction. Natural selection: individuals with certain heritable traits leave more offspring than individuals with other traits. o Why were these ideas a revolution? Science in the 1700s believed that the earth was only thousands of years old, that the environment is unchanging, that species have remained the same since creation and that there is no such thing as new species. o Descent with modification Species evolve and change over time from common ancestors. Mechanisms of evolution o Natural selection Nonrandom fixation of alleles conferring an advantage within an ecological context. What are the key ingredients of natural selection? Individuals within species vary. Some of these variations are heritable. More offspring are produced than can survive. Survival and reproduction are nonrandom (i.e., some traits help you survive and reproduce more than others). Where does variation come from? Variation is due to genetic changes: o Mutation: random introduction of new alleles o Recombination: assortment of alleles within a population How did this idea differ from Lamarcks hypothesis? Lamarcks hypothesis was that species change over time due to the inheritance of acquired characteristics. The main different in the two theories is that Darwins says the source of variation must be genetic and that acquired characteristics cannot be inherited. Does selection favor increasing complexity? Why or why not? Natural selection does not have a long-term goal of favoring increasing complexity, intelligence, long-life, ethical behavior or any other notion of what we see as good, progress, or advancement. o Genetic drift Random fixation or loss of alleles in a populationdue to chance in small populations....
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This note was uploaded on 02/12/2012 for the course EBIO 1220 taught by Professor Demig-addams during the Spring '07 term at Colorado.
- Spring '07