Understanding nucleotide variation in natural populations has been a subject of great interest for decades. However, many taxonomic groups, especially those with atypical life history attributes remain unstudied, and Drosophila is the only arthropod genus for which DNA polymorphism data are presently abundant. As a result of the recent release of the complete genome sequence and a wide variety ...

Shilajit is a mineral-rich complex organic compound used in the traditional system of Ayurvedic medicine for treating hypertension and improving the cardiac function with many herbomineral preparations. However, very little experimental evidence is available about its effect on the cardiac function. We used Daphnia as a model organism for observing the effect of shilajit on its heart due to its...

The effects of large grazers (Daphnia) and nutrients (nitrogen and phosphorus) on epilimnetic ciliate communities were investigated in eight large in situ enclosures. Contrasts in Daphnia abundance were created by stocking planktivorous fish (Phoxinus eos) in four of the eight enclosures. Contrasts in nutrients were created by adding nitrate and phosphate to two enclosures with fish and to two ...

In food-web studies, parasites are often ignored owing to their insignificant biomass. We provide evidence that parasites may affect trophic transfer in aquatic food webs. Many phytoplankton species are susceptible to parasitic fungi (chytrids). Chytrid infections of diatoms in lakes may reach epidemic proportions during diatom spring blooms, so that numerous free-swimming fungal zoospores (2-3...

Index words: Laurentian Great Lakes Vertical migration Zooplankton production Deep chlorophyll maxima Non-consumptive effects Zooplankton production plays a critical role in the Great Lakes ecosystem, and vertical migration, which is exhibited by many zooplankton species, could affect production. We examined the effects of water temperature and food resource gradients on the growth rate of zoop...

1. In a laboratory batch culture experiment, a diapause response of Daphnia magna to a simulated threat of fish predation was tested at various light intensities, which under natural conditions determine potential vulnerability of Daphnia to visual planktivorous fish. 2. Under moderate light intensity (1.4 lmol m s) that allows effective predation by fish, the proportion of females producing do...

To assess whether and how zooplankton communities respond to variations in temperature and how these assemblages change with eutrophication, we performed a large-scale, monthly survey from August 2011 to July 2012 to determine the seasonal and spatial variations in these communities in a high-altitude lake. A detrended correspondence analysis and a path analysis demonstrated that temperature an...

1. We evaluated the antipredator behaviour of Daphnia mendotae to the invasive invertebrate predator, Bythotrephes longimanus, and the consequent effect of the predator on prey growth rate (referred to as a non-lethal effect of the predator). 2. In a laboratory experiment, Daphnia in the absence of Bythotrephes kairomones remained in the top, warmer regions of experimental columns, whereas in t...

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...

Biochemical indices were investigated for their potential use as variables of sublethal toxicity in Daphnia (cholinesterase) and Chironomus (cholinesterase and biotransformation enzymes). Parathion, dichlorvos, and aldicarb caused dose-related inhibition of cholinesterase (ChE) in 24-h bioassays with both species. Ratios of Daphnia and Chironomus ChE IC50 values to corresponding immotility EC50...