Lecture%2022%20Coevolution

Lecture%2022%20Coevolution - 4/7/2009 Coevolution...

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4/7/2009 1 Coevolution and Red Queen Dynamic Queen Dynamics 1 Coevolution • Interdependent evolution of two or more species sharing any kind of ecological relationship • Interacting species can affect each others’ population dynamics • Species interactions can also cause reciprocal evolutionary changes 2 Types of Coevolution Mutualistic coevolution : all participants benefit as a result of the interaction (e.g. pollination, seed dispersal) Antagonistic coevolution : at least one participant suffers as a result of the interaction (e.g. predation, herbivory, parasitism) 3 “Thus I can understand how a flower and a bee might slowly become, either simultaneously or one after the other, modified and adapted in the most perfect Principle of co-adaptation adapted in the most perfect manner to each other, by continual preservation of individuals presenting mutual and slightly favourable deviations of structure” (Darwin, On the Origin of Species, p. 95) 4 Gene for gene coevolution in plant-pathogen interactions • Co-occuring genes for resistance in plants, and for virulence 5 (ability to infect a host)* in plant pathogens *plant pathologists use ‘aggressiveness’ for what we call ‘virulence’ Gene for gene systems • Resistance is dominant in host • Infectivity (virulence) is recessive in pathogen 6 • Could be many such alleles in both host and pathogen • For each (most) resistance genes there is (usually) a corresponding gene in the pathogen that can overcome the resistance
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4/7/2009 2 RR Rr rr AA No infect No infect Yes infect Aa No No Host genotype Pathogen 7 infect infect infect aa infect infect infect genotype R = resistant; r = susceptible A = avirulent; a = virulent Flor 1956 R_ rr A Resistance Disease Host genotype type A_ aa Disease Disease Pathogen geno 8 Host genotype R 1 r 1 , r 2 r 2 , r 3 r 3 r 1 r 1 , R 2 r 2 , r 3 r 3 r 1 r 1 , R 2 r 2 , R 3 r 3 a 1 a 1 , A 2 A 2 , A A infect No infect No infect 9 Pathogen genotype A 3 A 3 A 1 A 1 , a 2 a 2 , A 3 A 3 No infect infect No infect A 1 A 1 , a 2 a 2 , a 3 a 3 No infect infect Yes infect Gene for gene coevolution in natural populations • Wild flax Linum marginale 10 Jeremy Burdon & Pete Thrall Flax rust – Melampspora lini 11 12
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4/7/2009 3 Burdon 1994, 1995 Infection No infection
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This note was uploaded on 09/22/2009 for the course ECOL 4150 taught by Professor Prin during the Fall '08 term at University of Georgia Athens.

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Lecture%2022%20Coevolution - 4/7/2009 Coevolution...

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