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Immune investment and sperm competition in a beetle
Author(s) -
Drnevich Jenny M.,
Barnes Andrew I.,
SivaJothy Michael T.
Publication year - 2002
Publication title -
physiological entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.693
H-Index - 57
eISSN - 1365-3032
pISSN - 0307-6962
DOI - 10.1046/j.1365-3032.2002.00290.x
Subject(s) - biology , offspring , mating , sperm competition , sperm , immunity , investment (military) , parental investment , immune system , immunology , zoology , pregnancy , genetics , politics , political science , law
Individuals that invest more in immunity may not be able to invest as much in o\ther life history traits. The overall effects on fitness depend on the balance of investment in life history traits and unnecessary investment in immunity may lower fitness. Adult mealworm beetles ( Tenebrio molitor L.) modulate their investment according to the perceived risk of infection as larvae; the amount of investment can be assessed by body coloration. This prophylactic investment in immunity can be used to assess the costs of investment when no immune challenge is present. Whether investment in immunity is traded off against sperm competitive ability, another important fitness trait in insects, was investigated. Males that had invested more in immunity (dark males) competed against males that had invested less (light males) for fertilization of offspring. Dark males did lose sperm precedence over time, whereas light males did not. However, this decrease in sperm offensive ability may not result in decreased fitness for darker males under normal female mating frequencies; the decrease in offspring did not occur for 1 week, but females that have constant access to males mate once a day, which would negate any long‐term effects of male mating order. Thus, prophylactic investment in immunity does not produce immediate reductions in a male's ability to gain fertilizations. The costs to immune investment may be born by other fitness traits in T. molitor .