U of M BIOL 4802 - Coevolution (3 pages)

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Coevolution



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Coevolution

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Lecture Notes


Pages:
3
School:
University of Minnesota- Twin Cities
Course:
Biol 4802 - Evolution
Evolution Documents

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Evolution Lecture 27 Chapter 18 last chapter in course Topics for today Coevolution Example of tight coevolution Phylogenetic test of coevolution Expectations and examples Enemy victim Predator prey stop here Host parasite Mutualism Competition An example of tight coevolutionary dynamics figs and fig wasps o 750 species of fig o 300 known fig wasps o Both highly specialized o 60 my of coadaptation Life cycle of the fig wasp Other kinds of interactions among organisms 1 Resources o Nutrition or habitat 2 Competitors o Food space or habitat 3 Enemies o One is the consumable resource 4 Commensals o One benefits with neutral effects on the other 5 Mutualistic o Both benefit Interactions may vary o Over time o Different environments o Mutually beneficial in low N environments o Disadvantageous to the plant in high N soil Do interacting species coevolve o Yes if reciprocal genetic change occurs between interacting species due to natural selection they have imposed upon each other Specific coevolution Diffuse coevolution Escape and radiate coevolution Fig 18 2 How can we test for coevolution Example 1 Aphids and endosymbiotic bacteria a tightly codependent relationship o Aphids suck plant sap carbohydrates amino acids o Aphid can t make some essential amino acids o Supplied by bacteria symbionts o Plant supplies sugars C N glutamine o Interaction is 150 to 250 myo o In nature can t exist alone Examine phylogenies and look for parallel change Matching Association dates from the origin of the group Diverged in concert Little cross infection between Mismatching Cross infection and independent evolution Extinction and recolonization More likely if organism disperses Fig 18 3 Example 2 Gophers and Lice o Solitary life in individual tunnels o Rarely meet except to mate o Lice specialized to cling to hairs of host o Not highly mobile otherwise o Areas of congruence and lack of congruence Fig 18 3 Coevolution Enemies and victims Examples 1 Predator prey 2 Disease host 3 Plant



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