For many ecosystems, feral horses are increasingly becoming an important if not dominant component of ungulate biomass and hence influence on community dynamics. Yet we still know little of how horses contribute to key ecological interactions including predator-prey and indirect competitive relationships at a community level. Notably, feral species like horses can exhibit life-history traits that differ from that of native (mainly artiodactyl) herbivore competitors. Artificial selection for traits like increased, early, or extended reproduction that have yet to be reversed by natural selection, coupled with naturally selected differences in anatomy and behavior, in addition to unique management objectives for horses compared to other species, means that the dynamics of feral horse populations are not likely to align with what might be expected of other large herbivores. Unexpected population dynamics and inherent biological asymmetries between native ungulates and feral horses may therefore influence the former via direct competition for shared resources and through enemy-mediated interactions like apparent competition. In several localities feral horses now co-exist with multiple native prey species, some of which are in decline or are species at risk. Compounding risks to native species from direct or indirect competitive exclusion by horses is the unique nature and socio-political context of feral horse management, which tends towards allowing horse populations to be limited largely by natural, density-dependent factors. We summarize the inherent asymmetries between feral horse biology and that of other ungulate prey species with consequences for conservation, focusing on predator-prey and emerging indirect interactions in multi-prey systems, and highlight future directions to address key knowledge gaps in our understanding of how feral horses may now be contributing to the (re)structuring of food webs. Observations of patterns of rapid growth and decline, and associated skews in sex ratios of feral horse populations, indicate a heightened potential for indirect interactions among large ungulate prey species, where there is a prevalence of feral horses as preferred prey, particularly where native prey are declining. In places like western North America, we expect predator-prey interactions involving feral horses to become an increasingly important factor in the conservation of wildlife. This applies not only to economically or culturally important game species but also at-risk species, both predators (e.g., wolves [Canis lupus], grizzly bears [Ursus arctos]) and prey (e.g., woodland caribou [Rangifer tarandus caribou]), necessitating an ecological understanding of the role of horses in natural environments that goes beyond that of population control. © 2021 The Wildlife Society.

中文翻译：

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涉及野马和捕食者的生态相互作用：回顾对生物多样性保护的影响

对于许多生态系统，野马正日益成为有蹄类动物生物量的重要组成部分，因此对群落动态产生影响。然而，我们仍然对马如何促进关键的生态相互作用（包括捕食者-猎物和社区层面的间接竞争关系）知之甚少。值得注意的是，像马这样的野生物种可以表现出不同于本地（主要是偶蹄类）食草动物竞争对手的生活史特征。对于尚未被自然选择逆转的增加、早期或延长繁殖等特征的人工选择，加上自然选择的解剖结构和行为差异，以及与其他物种相比马的独特管理目标，意味着野马种群的动态不太可能与其他大型食草动物的预期一致。因此，本地有蹄类动物和野马之间意外的种群动态和固有的生物不对称性可能会通过对共享资源的直接竞争和通过敌人介导的互动（如明显的竞争）来影响前者。在一些地方，野马现在与多种本地猎物共存，其中一些正在减少或处于危险之中。野马管理的独特性质和社会政治背景使得马匹直接或间接竞争排斥对本地物种造成复合风险，这往往使马种群在很大程度上受到自然的、依赖密度的因素的限制。我们总结了野马生物学与其他有蹄类猎物物种之间固有的不对称性，对保护产生了影响，重点关注捕食者-猎物和多猎物系统中新出现的间接相互作用，并强调未来的方向，以解决我们对如何理解的关键知识差距野马现在可能有助于（重新）构建食物网。对快速增长和下降模式的观察，以及野马种群性别比例的相关偏差，表明大型有蹄类猎物之间间接相互作用的可能性增加，其中野马是首选猎物，特别是在本地猎物是本地猎物的地方。下降。在北美西部这样的地方，我们预计涉及野马的捕食者-猎物相互作用将成为野生动物保护中越来越重要的因素。这不仅适用于经济或文化上重要的猎物物种，也适用于危险物种，它们都是掠食者（例如，狼 [...]Canis lupus ]、灰熊 [ Ursus arctos ]）和猎物（例如林地驯鹿 [ Rangifer tarandus caribou ]），需要对马在自然环境中的作用进行生态理解，这超出了人口控制的范围。© 2021 野生动物协会。