Mixed‐species animal groups (MSGs) are widely acknowledged to increase predator avoidance and foraging efficiency, among other benefits, and thereby increase participants' fitness. Diversity in MSG composition ranges from two to 70 species of very similar or completely different phenotypes. Yet consistency in organization is also observable in that one or a few species usually have disproportionate importance for MSG formation and/or maintenance. We propose a two‐dimensional framework for understanding this diversity and consistency, concentrating on the types of interactions possible between two individuals, usually of different species. One axis represents the similarity of benefit types traded between the individuals, while the second axis expresses asymmetry in the relative amount of benefits/costs accrued. Considering benefit types, one extreme represents the case of single‐species groups wherein all individuals obtain the same supplementary, group‐size‐related benefits, and the other extreme comprises associations of very different, but complementary species (e.g. one partner creates access to food while the other provides vigilance). The relevance of social information and the matching of activities (e.g. speed of movement) are highest for relationships on the supplementary side of this axis, but so is competition; relationships between species will occur at points along this gradient where the benefits outweigh the costs. Considering benefit amounts given or received, extreme asymmetry occurs when one species is exclusively a benefit provider and the other a benefit user. Within this parameter space, some MSG systems are constrained to one kind of interaction, such as shoals of fish of similar species or leader–follower interactions in fish and other taxa. Other MSGs, such as terrestrial bird flocks, can simultaneously include a variety of supplementary and complementary interactions. We review the benefits that species obtain across the diversity of MSG types, and argue that the degree and nature of asymmetry between benefit providers and users should be measured and not just assumed. We then discuss evolutionary shifts in MSG types, focusing on drivers towards similarity in group composition, and selection on benefit providers to enhance the benefits they can receive from other species. Finally, we conclude by considering how individual and collective behaviour in MSGs may influence both the structure and processes of communities.

中文翻译：

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混合公司：了解混合物种动物群体的组成和组织的框架

混合物种动物群 (MSG) 被广泛认为可以增加避免捕食者和觅食效率等好处，从而增加参与者的健康。味精组成的多样性范围从 2 到 70 种非常相似或完全不同的表型。然而，组织的一致性也是可以观察到的，因为一个或几个物种通常对 MSG 的形成和/或维持具有不成比例的重要性。我们提出了一个二维框架来理解这种多样性和一致性，专注于两个个体之间可能的相互作用类型，通常是不同物种。一个轴代表个人之间交易的利益类型的相似性，而第二个轴表示产生的利益/成本的相对数量的不对称性。考虑到福利类型，一个极端代表单一物种群体的情况，其中所有个体都获得相同的补充性、与群体规模相关的利益，另一个极端包括非常不同但互补的物种的关联（例如，一个伙伴创造获得食物的机会，而另一个提供警觉）。社会信息的相关性和活动的匹配性（例如运动速度）在该轴的补充侧的关系中最高，但竞争也是如此；物种之间的关系将发生在沿此梯度的收益大于成本的点上。考虑到给予或接受的利益数额，当一个物种完全是利益提供者而另一个物种是利益使用者时，就会出现极端的不对称。在这个参数空间内，一些 MSG 系统被限制为一种交互，例如相似物种的鱼群或鱼类和其他分类群中的领导-跟随者相互作用。其他味精，例如陆生鸟群，可以同时包括各种补充和互补的相互作用。我们回顾了物种在 MSG 类型的多样性中获得的好处，并认为应该衡量利益提供者和使用者之间不对称的程度和性质，而不仅仅是假设。然后，我们讨论味精类型的进化转变，重点关注群体组成相似性的驱动因素，以及选择利益提供者以增强他们可以从其他物种获得的利益。最后，我们通过考虑味精中的个人和集体行为如何影响社区的结构和过程来得出结论。