Testing the cost of reproduction with the rotifer Brachionus patulus at different pH levels

摘要

In the present work, we tested the hypothesis that the cost of reproduction was evident under stressful conditions with the rotifer Brachionus patulus at different pH levels (5-10 at 1 unit intervals). We used sublethal pH levels (pH 5, 9, and 10) to simulate stressful conditions. We analyzed the correlations between age-specific fecundity (m_1, m_2, m_3, ...) versus future survival (l_(x + 1), l_(x + 2), l_(x + 3), ... for the entire lifespan) (survival costs) and future expectation of reproduction (V_1*, V_2*, V_3*,... for the entire lifespan) (reproductive costs), using the data obtained from life table demographic studies of B. patulus under stressful and favorable (pH 6, 7, and 8) pH levels. The results showed that significant negative correlations were observed between age-specific fecundity and future survival and future expectation of reproduction at all tested pH levels, indicating that costs of reproduction exist in the rotifer B. patulus under stressful and favorable pH conditions. However, the percentage of statistically significant negative correlations from total correlations of survival and reproductive costs differed greatly, depending on the tested pH conditions. The percentage of significant negative correlation of reproductive costs is significantly higher under stressful pH conditions (pH 5, 9, and 10) than favorable pH conditions (pH 6, 7, and 8). For survival costs, the same trends are also observed, suggesting that the costs of reproduction were more obvious under stressful pH than favorable pH.