Weeks Stephen C, Sassaman Clay
Biology Department, University of California, 92521, Riverside, CA, USA.
Oecologia. 1990 Apr;82(4):552-559. doi: 10.1007/BF00319800.
Life-history parameters (growth, reproduction, and survival) were measured from one genetically heterogeneous and three homogeneous populations of tadpole shrimp (Triops longicaudatus) raised under three competitive levels: 5, 10, and 16 shrimp per 38-1 aquarium. Comparisons were made between the homogeneous populations (three monomorphic selfing lines) and a heterogeneous population (a mixture of the three lines) to test for increased productivity in genetically variable populations, a prediction of the tangled bank hypothesis for a short-term advantage to sexual reproduction. In most comparisons, the mixture of inbred lines performed better than expected from their individual performances in pure cultures but did not outperform the best performing line in any comparison. Decomposition of the mixed culture's performance into performances of the component inbred lines showed that not all lines experienced release from competition in the mixed culture. No genotype X environment interaction was found for any of the three fitness correlates, indicating that all three lines performed similarly under the three competitive conditions. These results provide little support for the tangled bank hypothesis and suggest that the levels of heterogeneity necessary for detectable resource partitioning in these shrimp may involve factors not considered in this study.
在三种竞争水平下（每38升水族箱中分别饲养5只、10只和16只虾），对一个遗传异质群体和三个遗传同质群体的蝌蚪虾（长尾鲎虫）的生活史参数（生长、繁殖和存活）进行了测量。对同质群体（三个单态自交系）和异质群体（三个品系的混合物）进行了比较，以检验遗传可变群体中生产力的提高，这是对性繁殖短期优势的“纠结河岸”假说的一个预测。在大多数比较中，近交系的混合物表现优于它们在纯培养中的个体表现预期，但在任何比较中都没有超过表现最佳的品系。将混合培养的表现分解为各组成近交系的表现表明，并非所有品系在混合培养中都从竞争中解脱出来。对于三个适合度相关指标中的任何一个，均未发现基因型×环境互作，这表明所有三个品系在三种竞争条件下表现相似。这些结果几乎没有为“纠结河岸”假说提供支持，并表明在这些虾中检测到资源分配所需的异质性水平可能涉及本研究未考虑的因素。
