Both theory and experiments have demonstrated that sex can facilitate adaptation, potentially yielding a group-level advantage to sex. However, it is unclear whether this process can help solve the more difficult problem of the maintenance of sex within populations. Using experimental populations of the facultatively sexual rotifer Brachionus calyciflorus, we show that rates of sex evolve to hi...

Heterogeneity among prey in their susceptibility to predation is a potentially important stabilizer of predator-prey interactions, reducing the magnitude of population oscillations and enhancing total prey population abundance. When microevolutionary responses of prey populations occur at time scales comparable to population dynamics, adaptive responses in prey defense can, in theory, stabilize...

The ecological risk assessment of pesticides is generally based on toxicity data obtained from single-species laboratory experiments and does not take into account ecological interactions such as competition or predation. Intraspecific and interspecific competition are expected to result in additional stress and might increase the sensitivity of aquatic populations to pesticide contamination. T...

Puerto Viejo es un humedal costero de importancia para aves residentes y migratorias conformado por varios cuerpos agua estacionales, naturales artificiales con altas salinidades. Este ecosistema se encuentra ubicada al sur Lima, Perú. En junio 2004 llevaron a cabo censos la biodiversidad abundancia comunidad invertebrados, representando diferentes en 28 estaciones muestreo litorales distribuid...

Induction of mixis (sexual reproduction) in rotifers of the genus Brachionus is believed to be triggered by a chemical that is released into the water and accumulates at high population densities. However, direct and conclusive evidence for this hypothesis is thus far lacking. In this study, two mass cultures of the rotifer Brachionus plicatilis were monitored as they grew from low to high popu...

Populations of Moina micrura and Brachionus rubens in a deep waste treatment pond were exposed to the natural short-term fluctuations of unionised ammonia (90-min intervals of monitoring) that occur in the course of a day during a summer algal bloom. Under natural conditions, three replicate experiments were conducted in which water temperature, pH, dissolved oxygen, total ammonia, unionised am...

Six genera of rotifers including Philodina, Monostyla, Epiphanes, Euchlanis, Brachionus, and Asplanchna were exposed to oocysts of Cryptosporidium parvum cleaned of fecal debris. Unstained oocysts and those stained with fluorescein-conjugated monoclonal antibody were added to suspensions of viable rotifers and were examined by phase-contrast, differential interference contrast, and fluorescence...

The present investigation deals with the zooplanktons together with water quality of Panchganga river, in Kolhapur city, Maharashtra. This investigation was undertaken fora period of one year. The river Panchganga is a highly contaminated downstream with untreated sewage and industrial effluents, while flowing through Kolhapur city. The high value of CO2, BOD, COD, phosphate, nitrate, Zn, Fe, C...