Comparative studies on the life history characteristics of two Brachionus calyciflorus strains belonging to the same cryptic species

The life history characteristics of rotifers usually vary at different temperatures, depending on their species or strains. However, differences in the adaptability of rotifers sampled from two climatic zones and belonging to the same cryptic species in response to temperature changes remain undescribed. In this study, the phylogenetic relationships of Brachionus calyciflorus collecting from two climatic zones were reconstructed, and two clones of the same potential cryptic species were selected as representatives of two populations. The life history characteristics of the two B. calyciflorus strains were comparatively studied at four different temperatures (20 °C, 24 °C, 28 °C and 32 °C). The results showed that the responses of the life history traits of B. calyciflorus to temperature were strain-dependent. The Xishuangbanna strain is more suitable for growth at the higher temperature and that the Kunming strain grows preferentially at the lower temperature. Temperature significantly affected the durations of all developmental stages, offspring production, life expectancy at hatching, age-specific fecundity and survivorship of the two strains, which adopted the identical life history strategy (high population growth and low survivorship with increasing temperature). The discrimination of cryptic species is necessary to test the ecological or evolutionary characteristics of species.