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Quantifying the coevolutionary potential of multistep immune defenses
Author(s) -
Nuismer Scott L.,
Dybdahl Mark F.
Publication year - 2016
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/evo.12863
Subject(s) - coevolution , biology , effector , adaptation (eye) , evolutionary biology , local adaptation , genotype , host (biology) , genetics , innate immune system , acquired immune system , computational biology , gene , immune system , immunology , population , neuroscience , demography , sociology
Coevolutionary models often assume host infection by parasites depends on a single bout of molecular recognition. As detailed immunological studies accumulate, however, it becomes increasingly apparent that the outcome of host–parasite interactions more generally depends on complex multiple step infection processes. For example, in plant and animal innate immunity, recognition steps are followed by downstream effector steps that kill recognized parasites, with the outcome depending on an escalatory molecular arms race. Here, we explore the consequences of such multistep infection processes for coevolution using a genetically explicit model. Model analyses reveal that polymorphism is much greater at recognition loci than effector loci, that host–genotype by parasite–genotype ( G h × G p ) interactions are larger for the recognition step, and that the recognition step contributes more to local adaptation than the effector step. These results suggest that (1) local adaptation is more likely when fitness measures are related to recognition versus downstream effectors, (2) effector loci, while mechanistically important, are less likely to harbor the G h × G p variation that fuels coevolution, and (3) recognition loci are better candidates for genomic hotspots of coevolution.