We tested the hypothesis that ultraviolet photoreception contributes to prey search in small juvenile rainbow trout (Oncorhynchus mykiss) and pumpkinseed sunfish (Lepomis gibbosus) while foraging on Daphnia pulex. Small individuals of these species are ultraviolet-photosensitive zooplanktivores. For both species, prey pursuit distances and angles were larger under full-spectrum illumination tha...

A parasite's host range can have important consequences for ecological and evolutionary processes but can be difficult to infer. Successful infection depends on the outcome of multiple steps and only some steps of the infection process may be critical in determining a parasites host range. To test this hypothesis, we investigated the host range of the bacterium Pasteuria ramosa, a Daphnia paras...

Many organisms have the ability to alter their development in the presence of predators, leading to predator-induced defenses that reduce vulnerability to predation. In the water flea Daphnia pulex, small protuberances called 'neckteeth' form in the dorsal neck region in response to kairomone(s) released by predatory phantom midges (Chaoborus larvae). Although previous studies suggested that ka...

Two traditional species in the Daphnia pulex group (0. pulex and D. pulicmiu) are not completely reproductively isolated. The microhabitats they dominate are distinct but overlap geographically, and migration between the microhabitats is not uncommon. Their species identity is not fully supported by a recent molecular study. A laboratory experiment shows that Daphnia clones isolated from two po...

Ovaries were taken from five sexually mature amphipods: Gammarus fossarum, Gammarus pulex, Gammarus roeseli, Hyallela azteca and Parhyale hawaiensis. The soluble proteome extracted from individual pair of ovaries from five biological replicates was trypsin digested and the resulting peptides were analyzed by high resolution tandem mass spectrometry. The spectra were assigned with four protein s...

A concentration of lindane (y-hexachlorocyclohexane) of 0.05 mg liter-‘, much lower than the 48-h lethal concentration (LC,,) of 3.8 mg liter-‘, resulted in a 25% depression in the frequency of movements of filtering limbs and mandibles of Daphnia pulex in a food-free medium. Different instars (from 2nd to 8th) were affected to the same extent. Animals 6-l 2 h after molting were more sensitive ...