Data from: Predicting the outcome of competition when fitness inequality is variable

Traditional niche theory predicts that when species compete for one limiting resource in simple ecological settings the more fit competitor should exclude the less fit competitor. Since the advent of neutral theory ecologists have increasingly become interested both in how the magnitude of fitness inequality between competitors and stochasticity may affect this prediction. We used numerical simulations to investigate the outcome of two-species resource competition along gradients of fitness inequality (inequality in R*) and initial population size in the presence of demographic stochasticity. We found that the deterministic prediction of more fit competitors excluding less fit competitors was often unobserved when fitness inequalities were low or stochasticity was strong, and unexpected outcomes such as dominance by the less fit competitor, long-term co-persistence of both competitors or the extinction of both competitors could be common. By examining the interaction between fitness inequality and stochasticity our results mark the range of parameter space in which the predictions of niche theory break down most severely, and suggest that questions about whether competitive dynamics are driven by neutral or niche processes may be locally contingent.传统生态位理论预测：在简单生态场景中，当物种围绕单一限制性资源展开竞争时，适应性更强的竞争者理应排除适应性更弱的竞争者。自中性理论（neutral theory）问世以来，生态学家愈发关注竞争者间适应性差异的程度与随机性如何影响这一预测结果。本研究通过数值模拟，探究了在种群统计随机性存在的情况下，两物种资源竞争的结果随适应性差异（R*值差异）梯度与初始种群规模梯度的变化规律。研究发现，当适应性差异较小或随机性较强时，适应性更强的竞争者会排除弱势竞争者这一确定性预测往往无法成立；而诸如弱势竞争者占据优势、两物种长期共存乃至两物种均灭绝等非预期结果可能会频繁出现。通过分析适应性差异与随机性之间的相互作用，本研究明确了生态位理论预测失效最为显著的参数空间范围，并指出有关竞争动态究竟由中性过程还是生态位过程驱动的问题，可能具有局域偶然性。