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Published bySophie Barrett Modified over 9 years ago
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Selection and community interaction
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Selection: composite of the forces that limit the reproductive success of the genotype Fitness: comparative ability of a genotype to withstand selection Frequency dependent selection: selection against a gene depends on its frequency within the population
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Batesian mimicry: a palatable species mimics an unpalatable species and gains protection from predation Batesian mimicry Monarch butterfly (distasteful) Viceroy butterfly (tasty)
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Muellerian mimicry Muellerian mimicry: 2+ unpalatable species share similar aposematic coloration both species distasteful
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Selection & industrial melanism Peppered moth http://web.nmsu.edu/~wboeckle/biston.html
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Departure from highest fitness it is quite as dangerous to be conspicuously above a certain standard of organic excellence as it is to be conspicuously below the standard Bumpus 1899
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Departure from highest fitness Human birth weight
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Selection modes - stabilizing
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Selection modes - directional
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Selection modes - disruptive
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If some of these many species become modified and improved, others will have to be improved in a corresponding degree or they will be exterminated Darwin 1859 Community interactions
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Through the looking glass Lewis Carroll "Now, here, you see, it takes all the running you can do, to keep in the same place." Community interactions Red Queen hypothesis - organisms have to evolve as fast as they can just to stay in the same place
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Community interactions predationcommensalismmutualism amensalismneutralism competition - 0 + + 0 - species A species B
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Community interactions Competition - two groups depend on same limited resource so each group leads to a demonstrable reduction in numbers of the other
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Community interactions Resource partitioning - species minimize harmful effects of direct competition by using different aspects of their common environment
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Character displacement - measurable phenotypic differences accompany resource partitioning
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Community interactions Competitive exclusion - two groups cannot coexist in the same ecological niche
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Owing to the high geometrical rate of increase of all organic beings, each area is already fully stocked with inhabitants; and it follows from this, that as the favored forms increase in number, so generally will the less favored decrease and become rare Darwin, 1859 Community interactions
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Coevolution: evolutionary changes in 1+ species in response to changes in other species in the same community -can lead to an evolutionary ‘arms race’ Coevolution
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Cospeciation: speciation process that occurs in 2 interacting species simultaneously Coevolution
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