Niche apportionment models have only been applied once to parasite communities. Only the random assortment model (RA), which indicates that species abundances are independent from each other and that interspecific competition is unimportant, provided a good fit to 3 out of 6 parasite communities investigated. The generality of this result needs to be validated, however. In this study we apply 5...

Ceratomyxa shasta is a virulent myxosporean parasite of salmon and trout in the Pacific Northwest of North America. The parasite is endemic in the Klamath River, Oregon/California, where a series of dams prevent movement of fish hosts between the upper and lower parts of the basin. Ceratomyxa shasta exhibits a range of infection patterns in different fish species above and below the dams. We hy...

The reduction in host fitness caused by parasite infections (virulence) depends on infection intensity and the degree of damage per parasite. Environmental conditions can shape both virulence components, but contrast to intensity, environmental impacts per-parasite are poorly understood. Here, we studied effect ambient temperature damage, which is jointly determined ability parasites induce har...

In order to elucidate the transmission and dispersion routes used by the myxozoan parasite Enteromyxum scophthalmi Palenzuela, Redondo et Alvarez-Pellitero, 2002 within its host (Scophihalmus maximus L.), a detailed study of the course of natural and experimental infections was carried out. Purified stages obtained from infected fish were also used in in vitro assays with explants of uninfected...

Inbreeding can threaten population persistence by reducing disease resistance through the accelerated loss of gene diversity (i.e. heterozygosity). Such inbreeding depression can affect many different fitness-related traits, including survival, reproductive success, and parasite susceptibility. Empirically quantifying the effects of inbreeding on parasite resistance is therefore important for e...

Heritable population differences in immune gene expression following infection can reveal mechanisms of host immune evolution. We compared gene expression in infected and uninfected threespine stickleback (Gasterosteus aculeatus) from two natural populations that differ in resistance to a native cestode parasite, Schistocephalus solidus. Genes in both the innate and adaptive immune system were ...

Aggregation is commonly observed for macroparasites, but its adaptive value remains unclear. Heavy infestations intensities may lead to a decrease in some fitness-related traits of parasites (e.g. parasite fecundity or survival). However, to a dioecious parasite, increased aggregation could also increase the chance of finding individuals of the opposite sex. In a laboratory experiment, we teste...

Plerocercoids of the pseudophyllidean cestode Schistocephalus solidus infect the three-spined stickleback Gasterosteus aculeatus, with important consequences for the biology of host fish. Techniques for culturing the parasite in vitro and generating infective stages that can be used to infect sticklebacks experimentally have been developed, and the system is increasingly used as a laboratory mo...

A total of one hundred and twenty Clarias gariepinus comprising 30 dead and 30 live fishes were examined for protozoan parasites infestation, sixty each from the wild and a pond (cultured environment) over a period of six months. Ichthyophthirius multifiliis was the most common protozoan parasites found in C. gariepinus from the wild (River Benue) and cultured (pond) environments. These protozo...

Question: How does sexual ornamentation relate to parasite infection, host immune response and somatic condition status in male fish? Hypotheses: Zahavi’s (1975) handicap hypothesis proposes that producing secondary sexual traits represents a considerable handicap for males. Additionally, Hamilton and Zuk (1982) proposed that the expression of secondary sexual traits reveals a genetic resistanc...