notes 1 - Chapter 22 Descent w ith Modification: A Da r w...

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Chapter 22 Descent with Modification: A Darwinian View of Life What is Evolution and Adaptation? Evolution - Change over time of the genetic composition of a population - Descent of modern organisms with modification from preexisting organisms Evolutionary Adaptation - Accumulation of inherited characteristics that enhance organisms’ ability to survive in specific environments Pre-Darwinian Theory of Evolution Lamarck - Inheritance of acquired characteristics o Bodies of living organisms are modified through the use or disuse of parts o These modifications are inherited by offspring o This idea turned out to be wrong Evolution by Natural Science Darwin and Wallace - Developed the theory independently o Darwin – voyage of the Beagle o Wallace – naturalist in Indonesia Natural Selection - The unequal survival and reproduction of organisms due to environmental forces, resulting in the preservation of favorable adaptations - Process “selects” from what is available in the gene pool - New characteristics are not created on demand Mechanism behind Natural Selection *pg. 458 Think about the 100m dash track and field competition. How can we change this race to reflect the process of natural selection? Artificial Selection - Selective breeding of organisms to encourage the occurrence of desirable traits - Analogous to natural selection - Fig. 22.9 Concept 22.3: Evolution is supported by overwhelming amount of scientific evidence Examples of Natural Selection
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Fig. 22.13 Natural Selection and HIV Resistance Fossil Record - Show change in organism through time - Change in types of organisms o Past organisms differ from present day organisms o Many species have become extinct o Fig 22.15 - Fossil record not only provides evidence of small-scale changes, but of origin of major groups. For example, the cetaceans Homologous and Analogous Structures Homologous - Structure or other attributes in different species that resemble each other because of common ancestry Analogous - Structures that are similar in function, but not in structure and developmental and evolutionary origin Homologous structures: Mammalian forelimbs Fig 22.17 - Vertebrate embryos o All vertebrates share similar developmental genes o Differences arise by some genes being switched on or off at varying times during development - Biochemistry and Molecular Biology o DNA is universal genetic material o All life forms use approximately the same 20 amino acids to make protiens o All use ATP as the primary form of cellular energy o All use RNA and ribosomes to make protein Homologies and “Tree Thinking” Fig 22.19 Trees vs. Scala Naturae - Scala Naturae o Ladder of nature (pg. 453) - Evolution not about climbing the “ladder of nature” from lower to higher - Evolution is a “bush” with lineages branching from one another
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This note was uploaded on 02/14/2011 for the course BIOL 1201 taught by Professor Wishtichusen during the Spring '07 term at LSU.

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notes 1 - Chapter 22 Descent w ith Modification: A Da r w...

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