Seed dispersal is a critical mechanism for escaping specialist natural enemies. Despite this, mean dispersal distances can vary by an order of magnitude among plant species in the same community. Here, we develop a theoretical model to explore how interspecific differences in seed dispersal alter the impact of specialist natural enemies, both on their own and though a trade-off between seed dispersal and enemy susceptibility. Our model suggests that species are more able to recover from rarity if they have high dispersal because (1) seedlings are more likely to escape their parent’s natural enemies, (2) adults are more spread out, reducing the chance that a seed will disperse near conspecifics, and (3) seedlings compete less with kin for open gaps. Differences in dispersal do not produce stabilizing mechanisms—species with low dispersal are purely at a disadvantage and do not gain a novel niche opportunity. However, dispersal-susceptibility trade-offs will be equalizing, as species disadvantaged by low dispersal will benefit from being less susceptible to specialist natural enemies. This mechanism, unlike most mechanisms of dispersal-mediated coexistence, does not require that there is an abundance of empty space: high-dispersers gain an advantage by escaping from their enemies, not by colonizing empty habitat. Our study therefore suggests that differences in dispersal are unlikely to promote diversity on their own, but may strengthen other coexistence mechanisms.

种子传播是逃避专业天敌的关键机制。尽管如此，同一社区中植物物种的平均散布距离仍可能变化一个数量级。在这里，我们建立了一个理论模型，以探索种子散布的种间差异如何改变专家天敌的影响，既可以通过自身传播，也可以通过种子散布与敌人易感性之间的权衡取舍。我们的模型表明，如果物种具有较高的分散性，它们就更能够从稀有中恢复过来，因为（1）幼苗更容易逃脱其父母的天敌；（2）成年动物更易散开，从而减少了种子在附近散布的机会。 （3）幼苗与亲缘争夺空缺的竞争较少。分散的差异不会产生稳定机制-分散性低的物种纯粹处于不利地位，并且不会获得新的利基机会。但是，由于易分散性低的物种将从不易受专业天敌影响的利益中受益，因此分散敏感性之间的权衡将是均衡的。与大多数分散介导的共存机制不同，该机制不需要存在大量的空白空间：高分散性是通过逃避敌人而不是通过在空旷的殖民地中获得优势。因此，我们的研究表明，分散的差异不太可能独自促进多样性，但可能会增强其他共存机制。那些由于低扩散而处于不利地位的物种将因为不易受专业天敌的侵害而受益。与大多数分散介导的共存机制不同，该机制不需要存在大量的空白空间：高分散性是通过逃避敌人而不是通过在空旷的殖民地中获得优势。因此，我们的研究表明，分散的差异不太可能独自促进多样性，但可能会增强其他共存机制。那些由于低扩散而处于不利地位的物种将因为不易受专业天敌的侵害而受益。与大多数分散介导的共存机制不同，该机制不需要存在大量的空白空间：高分散性是通过逃避敌人而不是通过在空旷的殖民地中获得优势。因此，我们的研究表明，分散的差异不太可能独自促进多样性，但可能会增强其他共存机制。