One of the most common life history trade-offs in animals is the reduction in survivorship with increasing reproductive effort. Despite the prevalence of this pattern, its underlying physiological mechanisms are not well understood. Here we test the hypothesis that immune suppression mediates this phenotypic trade-off by manipulating reproductive effort and measuring immune function and mortality rates in the striped ground cricket, Allonemobius socius. Because A. socius males provide females with a hemolymph-based nuptial gift during copulation, and many structural components of immunity reside in the hemolymph, we also predicted that sexual selection may differentially affect how disease resistance evolves in males and females. We found that an increased mating effort resulted in a reduced immune ability, coupled with an increased rate in age-specific mortality for both sexes. Thus, immune suppression appears to be a link between reproductive effort and cost in this system. In addition, males and females appeared to differentially invest in several aspects of immunity prior to mating, with males exhibiting a higher concentration of circulating hemocytes and a superior bacterial defense capability. This pattern may be the result of previously established positive selection on gift size due to its affect on female fecundity. In short, female choice for larger gifts may lead to a sexually dimorphic immune ability.
How to translate text using browser tools
1 November 2004
IMMUNE SUPPRESSION AND THE COST OF REPRODUCTION IN THE GROUND CRICKET, ALLONEMOBIUS SOCIUS
Kenneth M. Fedorka,
Marlene Zuk,
Timothy A. Mousseau
ACCESS THE FULL ARTICLE
It is not available for individual sale.
This article is only available to subscribers.
It is not available for individual sale.
It is not available for individual sale.
Evolution
Vol. 58 • No. 11
November 2004
Vol. 58 • No. 11
November 2004
hemolymph
immunocompetence
life-history trade-off
sexual dimorphism
sexual selection
survivorship