不同pH条件下5种臂尾轮虫(Brachionus)的生殖代价

Testing the reproductive cost hypothesis with five Brachionus rotifer species under different pH conditions

研究了5种臂尾轮虫(萼花臂尾轮虫、方形臂尾轮虫、壶状臂尾轮虫、十指臂尾轮虫和角突臂尾轮虫)在不同pH条件下(pH 5,6,7,8,9,10)当前繁殖(mx)与未来存活(lx+1)、未来生殖(mx+1)和残余生殖价(V*x)的相关关系。结果表明,5种臂尾轮虫存活代价的相关系数在初始几个日龄组表现为正相关或负相关,在随后的大部分日龄组中,均表现为负相关,直至整个生命周期。相对于存活代价,5种臂尾轮虫繁殖代价和残余生殖代价的相关系数的变化幅度较大,但整体趋势仍就是大部分呈现负相关。因此可以推断,轮虫在不同pH条件下存在存活代价、繁殖代价和残余生殖代价。mx与lx+1对日龄组的回归分析有100%回归关系显著,mx与mx+1有97%回归关系显著,而mx与V*x有93%回归关系显著。因此推断,轮虫在不同pH条件下存活代价、繁殖代价和残余生殖代价的负相关性随着日龄组的增加而逐步增加。结果还发现,某些种类的轮虫(方形臂尾轮虫、壶状臂尾轮虫和十指臂尾轮虫)在胁迫的pH(酸性或碱性)条件下,其存活代价、繁殖代价和残余生殖代价较适宜pH(中性)条件下更为显著。

The correlations between present fecundity （mx） vs. future survival （lx＋1 ）, future fecundity （mx＋l） and residual reproductive value （ V^＋ ） were studied in five species of rotifers, Brachionus calyciflorus, B. quadridentatus, B. urceolaris, B. patulus and B. angularis under different pH conditions （ pH 5, 6, 7, 8, 9, 10）. The correlation coefficients of m vs. Ix＋1 （ survival costs） were positive or negative in early age-classes and were negative for the rest of lifespan. In contrast the correlation coefficients of mx vs. m＋1（reproductive costs） and mx vs. Vx（residual reproductive costs） varied greatly in the magnitude of correlation coefficients, and the majority showed a negative tendency. These results suggest that under different pH conditions there are survival costs, reproductive costs and residual reproductive costs in rotifers that support the reproductive cost hypothesis. Furthermore, 100% of the regressions of survival cost vs. cohort age-class, 97% of the regressions of reproductive cost vs. cohort age-class and 93% of the regressions of residual reproductive cost vs. cohort age-class were significant, indicating that the negative relationships were stronger in older age classes than in younger age classes. The results also showed that compared to favorable pH levels （neutral pH）, the negative correlations of B. quadridentatus, B. urce61aris and B. patulus were more pronounced under stressful pH conditions （acid or alkaline pH）.