Saito Yasuhisa, Miki Takeshi
Department of Mathematics, Pusan National University, Pusan 609-735, Republic of Korea.
Theor Popul Biol. 2010 Nov;78(3):173-82. doi: 10.1016/j.tpb.2010.07.003. Epub 2010 Jul 30.
Competition theory has developed separately for direct competition and for exploitative competition. However, the combined effects of the two types of competition on species coexistence remain unclear. To examine how intraspecific and interspecific direct competition contributes to the coexistence of species competing for a single resource, we constructed a chemostat-type resource competition model. With general functions for intraspecific and interspecific direct competition, we derived necessary and sufficient conditions (except for a critical case that rarely occurs in a biological sense) that determine the number of stably coexisting species. From these conditions, we found that the number of coexisting species is determined just by the invasibility of each species into subcommunities with a smaller number of species. In addition, using a combination of rigorous mathematical theory and a simple graphical method, we can demonstrate how the stronger intraspecific direct competition facilitates species invasion, leading to a larger number of coexisting species.
竞争理论已分别针对直接竞争和剥削性竞争进行了发展。然而，这两种竞争类型对物种共存的综合影响仍不明确。为了研究种内和种间直接竞争如何促进争夺单一资源的物种共存，我们构建了一个恒化器型资源竞争模型。通过种内和种间直接竞争的一般函数，我们推导出了决定稳定共存物种数量的充要条件（除了一个在生物学意义上很少出现的临界情况）。从这些条件中，我们发现共存物种的数量仅由每个物种侵入物种数量较少的子群落的可入侵性决定。此外，通过结合严谨的数学理论和简单的图形方法，我们可以证明更强的种内直接竞争如何促进物种入侵，从而导致更多的物种共存。
