SURVIVAL ANALYSIS OF 3 CLONES OF BRACHIONUS-PLICATILIS (ROTIFERA)

Age-specific survival schedules of females from three genetically diff erent clones of Brachionus plicatilis were analyzed at several environ mental conditions in the laboratory. Lifespan showed the expected decr ease with increasing temperature, but a general trend with salinity or genotype was not observed. Probability of death increased with age, a s tested by polynomial regression analysis of the survival curve and u sing theoretical mortality distributions. Three two-parameter models ( linear-exponential model, Weibull model, and Gompertz model) were fitt ed to the survival data. Fitting of these models to data was rather po or, but the Gompertz model and, to a lesser extent, the Weibull model fitted the data better than the linear-exponential model. Parameters o btained from the survival curve analyses were related to other demogra phic parameters. A significant relationship between the shape paramete r of the Gompertz model and the cohort generation time was detected, s uggesting, but not proving, an effect of reproductive effort on aging.