Matveev V F
A.N. Severtsov Institute of Evolutionary Morphology and Ecology of Animals, USSR Academy of Sciences, Leninsky prospekt 33, 117071, Moscow, Russia.
Oecologia. 1987 Dec;74(3):468-477. doi: 10.1007/BF00378946.
Isolated and mixed continuous cultures of Daphnia hyalina and Diaphanosoma brachyurum in lake water were maintained under laboratory conditions to elucidate demographic effects of competition. Population dynamics curves were obtained. Interspecific competition was revealed by the decrease in the average density of animals in the mixed versus isolated cultures and by the extinction of one species in the presence of the other. Within the first 50 days either Diaphanosoma (4 cases) or Daphnia (1 case) was the superior competitor, depending on the initial conditions. Further cultivation resulted in the extinction of Diaphanosoma in the mixed cultures. There were no statistically significant differences between the maximum rates of population increase (r ) in Daphnia and Diaphanosoma at the concentration of edible algae about 2·10 μmml(0.293 and 0.286 days, respectively). Time lags for density-dependent parameters of the populations were evaluated by means of rank cross-correlations. Regardless of the species identity the time lags of fecundity, birth rate, and the rate of population growth were significantly higher in the superior competitor. The initial conditions of culturing affected the time lags which in their turn influenced the outcome of the interaction. Enhanced competitive ability due to the maximized time lags in Daphnia was not associated with the loss of population stability. Conversely, it brought about destabilization of Diaphanosoma populations which seemed to be the ultimate cause of its extinction observed in the end of the experiment. Time lag of the population growth rate was well predicted based on the half-sum of time lags in birth and death rates (r=0.80, P<0.001). Daphnia responded to competition with a sharp shortening of the time lags of fecundity, birth rate, and the population growth rate. It increased clutch size and showed inverse relationship between the fecundity time lag and average fecundity even though it was strongly suppressed by Diaphanosoma. The competitive ability was not related to the percentage of adults in the populations. In contrast to the current belief the major result of interspecific competition in the experiment was not a decrease in the rate of population growth but was a reduction in population time lags.
在实验室条件下，对湖水中华透明溞和短尾秀体溞进行了单独培养和混合连续培养，以阐明竞争对种群统计学特征的影响。获得了种群动态曲线。种间竞争通过混合培养与单独培养中动物平均密度的降低以及一种物种在另一种物种存在时的灭绝得以体现。在前50天内，根据初始条件，秀体溞（4例）或透明溞（1例）是优势竞争者。进一步培养导致混合培养中秀体溞灭绝。在可食藻类浓度约为2·10⁶μm³/ml时，透明溞和中华透明溞的最大种群增长率（r）之间无统计学显著差异（分别为0.293天⁻¹和0.286天⁻¹）。通过秩交叉相关分析评估了种群密度依赖参数的时间滞后。无论物种身份如何，优势竞争者的繁殖力、出生率和种群增长率的时间滞后均显著更高。培养的初始条件影响时间滞后，而时间滞后又反过来影响相互作用的结果。透明溞因时间滞后最大化而增强的竞争能力与种群稳定性的丧失无关。相反，它导致了秀体溞种群的不稳定，这似乎是实验末期观察到其灭绝的最终原因。基于出生率和死亡率时间滞后的半和，能很好地预测种群增长率的时间滞后（r = 0.80，P < 0.001）。透明溞对竞争的反应是繁殖力、出生率和种群增长率的时间滞后急剧缩短。它增加了卵块大小，并且即使受到秀体溞的强烈抑制，繁殖力时间滞后与平均繁殖力之间仍呈负相关。竞争能力与种群中成年个体的百分比无关。与当前观点相反，实验中种间竞争的主要结果不是种群增长率的降低，而是种群时间滞后的减少。
