Loreau M, Ebenhöh W
Department of Animal Biology, Free University of Brussels, Belgium.
Theor Popul Biol. 1994 Aug;46(1):58-77. doi: 10.1006/tpbi.1994.1019.
Complex life cycles are life histories in which abrupt ontogenetic transformations and niche shifts occur at the transition between stages. The effects of this niche differentiation between stages on coexistence between species are investigated using a simple discrete model of two-stage populations. The model incorporates exploitation competition for limiting resources within stages, between stages, and between species. While species with simple life cycles can never coexist at equilibrium, stable coexistence is shown to be possible between species with complex life cycles provided that (1) one species is more efficient in resource utilization at low resource abundance in the larval stage while the other is more efficient at low resource abundance in the adult stage; and (2) each species is mainly limited by that stage which is less efficient at low resource abundance. Stable coexistence is somewhat easier between a species with a simple life cycle and one with a complex life cycle. It requires that (1) the species with the simple life cycle should not be decidedly more efficient than that with the complex life cycle in utilizing the resource on which it lives; and (2) the main resource limitation for the species with a complex life cycle should occur in that stage which escapes competition with the species with a simple life cycle. Lastly, a complex life cycle can offer a decisive competitive superiority over a simple life cycle in interspecific competition, which suggests that competition can be a driving force of the evolution of complex life cycles.
复杂生命周期是指在各阶段转换时会发生突然的个体发育转变和生态位转移的生活史。利用一个简单的两阶段种群离散模型，研究了各阶段间这种生态位分化对物种间共存的影响。该模型纳入了各阶段内、各阶段间以及物种间对有限资源的利用性竞争。虽然具有简单生命周期的物种在平衡状态下永远无法共存，但研究表明，具有复杂生命周期的物种间有可能实现稳定共存，条件是：（1）一个物种在幼虫阶段资源丰度较低时资源利用效率更高，而另一个物种在成虫阶段资源丰度较低时资源利用效率更高；（2）每个物种主要受资源丰度较低时效率较低的那个阶段的限制。具有简单生命周期的物种和具有复杂生命周期的物种之间实现稳定共存相对更容易一些。这需要：（1）具有简单生命周期的物种在利用其生存资源方面不应明显比具有复杂生命周期的物种效率更高；（2）具有复杂生命周期的物种的主要资源限制应出现在与具有简单生命周期的物种不存在竞争的那个阶段。最后，在种间竞争中，复杂生命周期相对于简单生命周期可提供决定性的竞争优势，这表明竞争可能是复杂生命周期进化的驱动力。
