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Schistocephalus Solidus (Schistocephalu + solidus)
Selected AbstractsCostly carotenoids: a trade-off between predation and infection risk?JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2005I. T. VAN DER VEEN Abstract Carotenoid reserves in copepods seem costly in terms of predation risk because they make individuals conspicuous. However, carotenoids also seem to play an important role in immune defence as free radical scavengers. To test whether predation risk influences carotenoid levels and whether changes in carotenoid levels are related to changes in immune defence, I examined individual changes in large carotenoid and other lipid droplets upon exposure to predation risk and subsequent exposure to parasites in the copepod Macrocyclops albidus. Copepods reduced carotenoid reserves upon exposure to predators, through which they potentially avoided the costs of being conspicuous under predation risk. Thus, the size of carotenoid reserves is a plastic trait. Such a decrease in carotenoid reserves may also have a negative impact on the copepods' immune system as individuals that decreased their reserves suffered higher parasite prevalence upon exposure to the cestode Schistocephalus solidus. These results suggest that carotenoid reserves may be individually optimized to trade-off each individual's unique costs (predation risk) and benefits (immune defence) of having these reserves. [source] Isolation and characterization of microsatellite loci from the tapeworm Schistocephalus solidusMOLECULAR ECOLOGY, Issue 11 2000Thomas Binz [source] Evolutionary significance of fecundity reduction in threespine stickleback infected by the diphyllobothriidean cestode Schistocephalus solidusBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2010DAVID C. HEINS Parasites may cause fecundity reduction in their hosts via life-history strategies involving simple nutrient theft or manipulation of host energy allocation. Simple theft of nutrients incidentally reduces host energy allocation to reproduction, whereas manipulation is a parasite-driven diversion of energy away from host reproduction. We aimed to determine whether the diphyllobothriidean cestode parasite Schistocephalus solidus causes loss of fecundity in the threespine stickleback fish (Gasterosteus aculeatus) through simple nutrient theft or the manipulation of host energy allocation. In one stickleback population (Walby Lake, Matanuska-Susitna Valley, Alaska), there was no difference in the sizes and ages of infected and uninfected reproducing females. Lightly- and heavily-infected females produced clutches of eggs, but increasingly smaller percentages of infected females produced clutches as the parasite-to-host biomass ratio (PI) increased. Infected, clutch-bearing sticklebacks showed reductions in clutch size, egg mass, and clutch mass, which were related to increases in PI and reflected a reduction in reproductive parameters as growth in parasite mass occurs. The findings obtained for this population are consistent with the hypothesis of simple nutrient theft; however, populations of S. solidus in other regions may manipulate host energy allocation. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 835,846. [source] Variation in stickleback head morphology associated with parasite infectionBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2009NIELS J. DINGEMANSE Parasites can affect host phenotypes, influencing their ecology and evolution. Host morphological changes occurring post-infection might result from pathological by-products of infection, or represent adaptations of hosts or parasites. We investigated the morphology of three-spined sticklebacks, Gasterosteus aculeatus, from a population naturally infected with Schistocephalus solidus, which grows to large sizes in their body cavity. We examined local effects of infection on trunk shape, which are imposed directly by the bulk of the growing parasite, and distant effects on head morphology. We show that trunk shape differed between infection classes, and was affected more severely in fish with heavier total parasite mass. We further show unexpected differences in head morphology. The heads of infected fish were reduced in size and differently shaped to those of non-infected fish, with infected fish having deeper heads. Importantly, both head size and shape were also affected more severely in fish with heavier total parasite mass. This latter result suggests that differences in morphology are caused by post-infection changes. Such changes may be incidental, evolutionarily neutral ,side effects' of infection. However, because head morphology affects foraging ecology, such changes are likely to have fitness consequences for hosts, and may constitute adaptations, either of hosts or of parasites. We discuss our finding in the context of the evolution of phenotypic plasticity, and suggest testable hypotheses examining the proximate mechanisms underlying these morphological effects and their potential evolutionary basis. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 759,768. [source] | ||||||||||