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Competitiveness and life‐history characteristics of Daphnia with respect to susceptibility to a bacterial pathogen
Author(s) -
Little T. J.,
Carius H.J.,
Sakwinska O.,
Ebert D.
Publication year - 2002
Publication title -
journal of evolutionary biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.289
H-Index - 128
eISSN - 1420-9101
pISSN - 1010-061X
DOI - 10.1046/j.1420-9101.2002.00436.x
Subject(s) - biology , daphnia , daphnia magna , resistance (ecology) , ecology , pathogen , genotype , fixation (population genetics) , population , genetic variation , zoology , life history , population genetics , host (biology) , life history theory , genetics , crustacean , gene , demography , chemistry , organic chemistry , toxicity , sociology
Costs of resistance, i.e. trade‐offs between resistance to parasites or pathogens and other fitness components, may prevent the fixation of resistant genotypes and therefore explain the maintenance of genetic polymorphism for resistance in the wild. Using two approaches, the cost of resistance to a sterilizing bacterial pathogen were tested for in the crustacean Daphnia magna . First, groups of susceptible and resistant hosts from each of four natural populations were compared in terms of their life‐history characteristics. Secondly, we examined the competitiveness of nine clones from one population for which more detailed information on genetic variation for resistance was known. In no case did the results show that competitiveness or life history characteristics of resistant Daphnia systematically differed from susceptible ones. These results suggest that costs of resistance are unlikely to explain the maintenance of genetic variation in D. magna populations. We discuss methods for measuring fitness and speculate on which genetic models of host‐parasite co‐evolution may apply to the Daphnia ‐microparasite system.