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HOST‐PARASITE AND GENOTYPE‐BY‐ENVIRONMENT INTERACTIONS: TEMPERATURE MODIFIES POTENTIAL FOR SELECTION BY A STERILIZING PATHOGEN
Author(s) -
Mitchell Suzanne E.,
Rogers Emily S.,
Little Tom J.,
Read Andrew F.
Publication year - 2005
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/j.0014-3820.2005.tb00895.x
Subject(s) - biology , parasite hosting , virulence , host (biology) , genotype , context (archaeology) , selection (genetic algorithm) , balancing selection , daphnia , genetic variation , genetic diversity , zoology , genetic variability , evolutionary biology , ecology , genetics , population , gene , paleontology , demography , crustacean , artificial intelligence , sociology , world wide web , computer science
Parasite‐mediated selection is potentially of great importance in modulating genetic diversity. Genetic variation for resistance, the fuel for natural selection, appears to be common in host‐parasite interactions, but responses to selection are rarely observed. In the present study, we tested whether environmental variation could mediate infection and determine evolutionary outcomes. Temperature was shown to dramatically alter the potential for parasite‐mediated selection in two independent laboratory infection experiments at four temperatures. The bacterial parasite, Pasteuria ramosa , was extremely virulent at 20d̀C and 25d̀C, sterilizing its host, Daphnia magna , so that females often never produced a single brood. However, at 10d̀C and 15d̀C, the host‐parasite interaction was much more benign, as nearly all females produced broods before becoming sterile. This association between virulence and temperature alone could stabilize coexistence and lead to the maintenance of diversity, because it would weaken parasite‐mediated selection during parts of the season. Additionally, highly significant genotype‐by‐environment interactions were found, with changes in clone rank order for infection rates at different temperatures. Our results clearly show that the outcome of parasite‐mediated selection in this system is strongly context dependent.