10- Natural Selection - Evolution & Natural Selection...

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The theory of evolution - Evolution is “just a theory” - That puts it on the same level as - Atomic structure - Rutherford/Bohr model - Quantum mechanics - The attraction of large bodies in space - Gravitation - General Relativity - Chemistry and physics are governed by natural laws, why not biology? Confusion of evolution - There has been a confusion of ideas - Evolution/the Origin of life - Origin of life is not known - We have ideas, some data, but no solid conclusions - Evolution/religion - The supposed conflict between religion and evolution - Religion is faith-based, evolution is based on physical evidence Two ideas of evolution - Evolution really consists of two ideas - Evolution (change) has occurred - Charge in organisms is well documented - Something has changed from one population to the next - Natural selection is a mechanism that can drive evolution - The theory of natural selection is a well supported mechanism of change The poster boys of evolution - Alfred Wallace - Charles Darwin Evolution - Idea of biological evolution actually predates Darwin and Wallace - Ancient Greek philosophers ~520 B.C. - De Buffon suggested evolution occurred - said that the environment was the agent of change - Proposed no mechanism, only an agent - Provided no facts or experimentation - The idea suffered for a lack of support and clarity Inheritance of acquired characteristics - Lamarck suggested a mechanism of evolution
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- Inheritance of acquired characteristics - Traits that a certain person acquires during a lifetime are inherited by offspring - Example: guy lost his finger, kids born w/o a finger - Body and behavioral changes that develop during the life of an organism are passed on to offspring - This has never been verified by observation or experimentation - Doesn’t happen. Inheritance of acquired characteristics Figure 20.1a Natural selection - Darwin and Wallace suggested natural selection as a mechanism to explain evolution (1838/1858) - Traits favorable in an environment become more common through differences in individual survival and reproduction - Change occurs because some organisms reproduce better - Not all adults contribute equally to the next generation (differential reproduction) - Some individuals will have a lot of offspring, some don’t - Most successful individuals will reproduce more
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Requirements for selection - Requirements for selection: - Heritable variation exists (genetic) - Some difference in organisms in the wild (different color/shape/sizes) - Variation has to be genetically encoded, has to be heritable - Excess reproduction - More individuals we can support in an area - Struggle for existence because environment can’t support everyone
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This note was uploaded on 03/25/2010 for the course BIO 11000 taught by Professor Friedman during the Spring '10 term at Purdue University-West Lafayette.

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10- Natural Selection - Evolution & Natural Selection...

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