Hartt L, Haefner J W
Department of Fisheries and Wildlife and the Ecology Center, Utah State University, Logan, Utah 84322-5210, USA.
Theor Popul Biol. 1998 Aug;54(1):50-61. doi: 10.1006/tpbi.1997.1361.
The relative effects of phenotypic variation and trait correlations on mean population fitness are poorly understood. Moreover, when fitness is evaluated in the context of ecological processes such as predation, theoretical development is lacking. To address this deficiency, we simulate a predator-prey system, where the prey population is composed of three phenotypes that differ in fecundity and predator evasiveness. We use equilibrium population size and allele frequencies to examine the relative effects of trait variation and correlation on mean population fitness. When no correlation is present, increasing variance in either trait increases equilibrium population size. Negative correlations coupled with increasing variance in both traits increases equilibrium population size. Positive correlations are more likely to increase equilibrium population size when variances are inversely related. With respect to allele frequencies, as variance in both traits increases, populations with positive correlations experience greater loss of genetic diversity than those with negative correlations. Thus, selection as a dynamic ecological process (frequency-dependent predation) favors trade-offs, whether they are between trait means (negative correlations) or variances (positive correlations).
表型变异和性状相关性对种群平均适合度的相对影响目前还知之甚少。此外，当在诸如捕食等生态过程的背景下评估适合度时，理论发展仍显不足。为了弥补这一缺陷，我们模拟了一个捕食者 - 猎物系统，其中猎物种群由三种在繁殖力和躲避捕食者能力方面存在差异的表型组成。我们使用平衡种群大小和等位基因频率来检验性状变异和相关性对种群平均适合度的相对影响。当不存在相关性时，任一性状方差的增加都会使平衡种群大小增加。负相关以及两个性状方差的同时增加会使平衡种群大小增加。当方差呈反比关系时，正相关更有可能增加平衡种群大小。关于等位基因频率，随着两个性状方差的增加，具有正相关的种群比具有负相关的种群经历更大的遗传多样性损失。因此，作为一个动态生态过程的选择（频率依赖型捕食）有利于权衡，无论这种权衡是在性状均值之间（负相关）还是方差之间（正相关）。
