Redpath Museum and Department of Biology, McGill University, Montréal, QC, Canada.
J Evol Biol. 2011 Oct;24(10):2186-96. doi: 10.1111/j.1420-9101.2011.02348.x. Epub 2011 Jun 27.
Many factors could influence progress towards sympatric speciation. Some of the potentially important ones include competition, mate choice and the degree to which alternative sympatric environments (resources) are discrete. What is not well understood is the relative importance of these different factors, as well as interactions among them. We use an individual-based numerical model to investigate the possibilities. Mate choice was modelled as the degree to which male foraging traits influence female mate choice. Competition was modelled as the degree to which individuals with different phenotypes compete for portions of the resource distribution. Discreteness of the environment was modelled as the degree of bimodality of the underlying resource distribution. We find that strong mate choice was necessary, but not sufficient, to cause sympatric speciation. In addition, sympatric speciation was most likely when the resource distribution was strongly bimodal and when competition among different phenotypes was intermediate. Even under these ideal conditions, however, sympatric speciation occurred only a fraction of the time. Sympatric speciation owing to competition on unimodal resource distributions was also possible, but much less common. In all cases, stochasticity played an important role in determining progress towards sympatric speciation, as evidenced by variation in outcomes among replicate simulations for a given set of parameter values. Overall, we conclude that the nature of competition is much less important for sympatric speciation than is the nature of mate choice and the underlying resource distribution. We argue that an increased understanding of the promoters and inhibitors of sympatric speciation is best achieved through models that simultaneously evaluate multiple potential factors.
许多因素会影响同域物种形成的进展。其中一些潜在的重要因素包括竞争、配偶选择以及可供选择的同域环境（资源）的离散程度。人们不太了解的是这些不同因素的相对重要性，以及它们之间的相互作用。我们使用基于个体的数值模型来研究这些可能性。配偶选择被建模为雄性觅食特征影响雌性配偶选择的程度。竞争被建模为不同表型个体对资源分布部分的竞争程度。环境的离散性被建模为基础资源分布的双峰程度。我们发现，强烈的配偶选择是必要的，但不足以导致同域物种形成。此外，当资源分布强烈双峰且不同表型之间的竞争处于中等水平时，同域物种形成最有可能发生。然而，即使在这些理想条件下，同域物种形成也只发生了一小部分时间。在单峰资源分布上竞争引起的同域物种形成也是可能的，但要少见得多。在所有情况下，随机性在决定同域物种形成的进展方面起着重要作用，这可以从给定参数值集合的重复模拟结果中的变化中得到证明。总的来说，我们得出结论，竞争的性质对于同域物种形成的重要性远低于配偶选择和基础资源分布的性质。我们认为，通过同时评估多个潜在因素的模型，才能更好地理解同域物种形成的促进因素和抑制因素。
