The sicker sex: understanding male biases in parasitic infection, resource allocation and fitness.

摘要: The “sicker sex” idea summarizes our knowledge of sex biases in parasite burden and immune ability whereby males fare worse than females. theoretical basis this is that because invest more on mating effort females, the former pay costs by having a weaker system thus being susceptible to parasites. Females, conversely, have greater parental investment. Here we tested following: a) whether both sexes differ their defend against parasites using natural host-parasite system; b) differences resource allocation conflict between investment traits sexes; and, c) effect parasitism survival for sexes. We used number insect damselfly species as study subjects. For (a), quantified gregarine mite parasites, experimentally manipulated levels during adult ontogeny. (b), first, food ontogeny recorded thoracic fat gain (a proxy effort) abdominal weight investment) Secondly when adults were about become sexually mature, number. (c), infected male female different ages measured survival. Males consistently showed females apparently due an increased production males. Conversely, invested weight. These independent how much food/infecting provided. cost was had reduced Our results provide mechanism understanding sexual defense well consequences each sex.