Population density, sexual reproduction and diapause in monogonont rotifers: new data for Brachionus and a review

摘要: Diapausing, fertilized eggs in monogonont rotifers typically are formed after an environmental signal induces amictic females to produce mictic daughters. Mictic lay haploid that may develop parthenogenetically into males, or be and diapausing, female embryos called resting eggs. Laboratory experiments demonstrate crowding is the for production of strains Brachionus calyciflorus from Texas, Spain Germany, a strain variabilis Spain. In these experiments, newborn were cultured singly large small volumes give lowand high-density treatments. Therefore, induction due exclusively population density cannot attributed grouping effect involving some interaction among individuals. B. very sensitive density; had 30 ml prevent appreciable Crowding now known initiation sexuality diapause four species Brachionus, two Epiphanes, Rhinoglena frontalis. The chemical mediates this response somehow influences oocytes maternal body cavity differentiate females. Aggregation individuals natural systems facilitate rotifers, suppressed early generations egg, assuring clonal populations will attain higher densities before committing sexual reproduction. Fitness benefits mictic-female crowding, other signals (dietary tocopherol, long photoperiod), discussed.