Weeks Stephen C
Center for Theoretical and Applied Genetics, Cook College/Rutgers University, P.O. Box 231, 08903, New Brunswick, NJ, USA.
Oecologia. 1993 Mar;93(3):307-314. doi: 10.1007/BF00317871.
Models of resource allocation strategies predict an array of life-history responses of individuals living in resource-stressed versus non-stressed environments. I tested a number of these predictions using three fish strains (a sexual and two clonal strains) in high and low density treatments. To examine the plasticity of life-history traits in females raised in these two environments, I measured survival, growth, egg production, egg size, and proportion mature at 10 weeks of age. Survival was not affected by density treatment. However, both growth and overall egg production were lower in females from the high density treatments, and reproductive maturity was significantly delayed at the high density for all strains. Egg production per unit size was not affected by density in any strain, signifying that differences in the numbers of eggs produced was merely a reflection of the differences in size of fish in the two density treatments. Egg size was also unaffected by density in all strains. These results are related to models of resource allocation in stressful environments. There was a consistent pattern of increased reproductive investment in the sexual strain relative to the two clonal strains. The sexual strain matured earlier, produced more eggs per unit body weight, and had larger eggs than either clone at both densities. These results are interpreted by considering the predicted adaptive responses of these three strains to the long-term environmental differences in their natural habitats.
资源分配策略模型预测了生活在资源紧张与资源非紧张环境中的个体的一系列生活史反应。我使用三种鱼类品系（一种有性生殖品系和两种克隆品系）在高密度和低密度处理条件下对其中一些预测进行了测试。为了研究在这两种环境中饲养的雌性个体生活史特征的可塑性，我测量了10周龄时的存活率、生长率、产蛋量、蛋的大小以及成熟比例。存活率不受密度处理的影响。然而，高密度处理组的雌性个体的生长和总体产蛋量均较低，并且所有品系在高密度条件下生殖成熟都显著延迟。任何品系中单位大小的产蛋量都不受密度影响，这表明产蛋数量的差异仅仅反映了两种密度处理下鱼大小的差异。所有品系的蛋大小也不受密度影响。这些结果与压力环境下的资源分配模型相关。相对于两种克隆品系，有性生殖品系存在生殖投资增加的一致模式。在两种密度条件下，有性生殖品系都比任何一种克隆品系成熟更早，单位体重产蛋更多，并且蛋更大。通过考虑这三种品系对其自然栖息地长期环境差异的预测适应性反应来解释这些结果。
