(1) Diffuse competition affects per capita rates of population increase among species that exploit similar resources, and thus can be an important structuring force in ecological communities. Diffuse competition has traditionally been studied within taxonomically similar groups, although distantly related intraguild species are likely also to compete to some degree. (2) We assessed diffuse competition between mammalian and reptilian predators at sites in central Australia over 24 years. Specifically, we investigated the effect of dasyurid marsupial abundance on the diet breadth of three groups of lizards (nocturnal dietary generalists, diurnal dietary generalists and dietary specialists). (3) Nocturnal generalist lizards had progressively narrower diets as dasyurid abundance increased. The diet breadth of diurnal generalist lizards was unaffected by overall dasyurid abundance, but was restricted by that of the largest dasyurid species (Dasycercus blythi). Ant- and termite-specialist lizards were unaffected by dasyurid abundance. (4) Diffuse competition, mediated by interference, between dasyurids and nocturnal generalist lizards appears to have strong effects on these lizards, and is the first such between-class interaction to be described. Diffuse interactions may be widespread in natural communities, and merit further investigation among other disparate taxon groups that occur in the same ecological guilds.

中文翻译：

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阶级冲突：哺乳动物和爬虫类捕食者之间的扩散竞争

（1）扩散竞争影响利用相似资源的物种的人均人口增长率，因此可能成为生态群落的重要结构力量。传统上，在分类学上相似的群体中研究了扩散竞争，尽管远缘行会内物种也可能在某种程度上竞争。（2）我们评估了澳大利亚中部地区过去24年中哺乳动物和爬虫类捕食者之间的扩散竞争。具体来说，我们调查了dasyurid有袋动物的丰度对三组蜥蜴（夜间饮食通才，昼夜饮食通才和饮食专家）的饮食广度的影响。（3）随着dasyurid丰度的增加，夜间通才蜥蜴的饮食逐渐缩小。Dasycercus blythi）。蚂蚁和白蚁专家蜥蜴不受dasyurid丰度的影响。（4）dasyurids和夜间通才蜥蜴之间的干扰竞争介导的扩散竞争似乎对这些蜥蜴有很强的影响，并且这是首次被描述的这种类间相互作用。扩散相互作用可能在自然社区中广泛传播，值得在同一生态行会中出现的其他不同分类群之间进行进一步调查。