H. Richner et al., PATERNAL INVESTMENT AFFECTS PREVALENCE OF MALARIA, Proceedings of the National Academy of Sciences of the United Statesof America, 92(4), 1995, pp. 1192-1194
Both reproduction and parasite defense can be costly, and an animal ma
y face a trade-off between investing in offspring or in parasite defen
se, In contrast to the findings from nonexperimental studies that the
poorly reproducing individuals are often the ones with high parasite l
oads, this life-history view predicts that individuals with high repro
ductive investment will show high parasite prevalence, Here we provide
an experimental confirmation of a positive association between parent
al investment levels of male great tits Paras major and the prevalence
of Plasmodium spp, a hematozoa causing malaria in various bird specie
s. We manipulated brood size, measured feeding effort of both males an
d females, and assessed the prevalence of the hemoparasite from blood
smears. In enlarged broods the males, but not the females, showed sign
ificantly higher rates of food provisioning to the chicks, and the rat
e of malarial infection was found to be more than double in male, but
not female, parents of enlarged broods. The findings show that there m
ay be a trade-off between reproductive effort and parasite defense of
the host and also suggest a mechanism for the well documented trade-of
f between current reproductive effort and parental survival.