The Late Quaternary extinctions of megafauna (defined as animal species > 44.5 kg) reduced the dispersal of seeds and nutrients, and likely also microbes and parasites. Here we use body‐mass based scaling and range maps for extinct and extant mammal species to show that these extinctions led to an almost seven‐fold reduction in the movement of gut‐transported microbes, such as Escherichia coli (3.3–0.5 km² d⁻¹). Similarly, the extinctions led to a seven‐fold reduction in the mean home ranges of vector‐borne pathogens (7.8–1.1 km²). To understand the impact of this, we created an individual‐based model where an order of magnitude decrease in home range increased maximum aggregated microbial mutations 4‐fold after 20 000 yr. We hypothesize that pathogen speciation and hence endemism increased with isolation, as global dispersal distances decreased through a mechanism similar to the theory of island biogeography. To investigate if such an effect could be found, we analysed where 145 zoonotic diseases have emerged in human populations and found quantitative estimates of reduced dispersal of ectoparasites and fecal pathogens significantly improved our ability to predict the locations of outbreaks (increasing variance explained by 8%). There are limitations to this analysis which we discuss in detail, but if further studies support these results, they broadly suggest that reduced pathogen dispersal following megafauna extinctions may have increased the emergence of zoonotic pathogens moving into human populations.

中文翻译：

---

大型动物的减少减少了病原体的传播，这可能增加了突发性传染病

大型动物的第四纪晚期灭绝（定义为> 44.5 kg的动物物种）减少了种子和养分的扩散，也可能减少了微生物和寄生虫的扩散。在这里，我们对灭绝和现存的哺乳动物物种使用基于身体质量的比例尺和范围图，显示这些灭绝导致肠道转运微生物（如大肠杆菌）（3.3-0.5 km ²  d）的运动减少了近七倍。^-1）。同样，灭绝导致媒介传播病原体的平均本底范围减少了七倍（7.8-1.1 km ²）。为了理解其影响，我们创建了一个基于个体的模型，其中，在20000年之后，家庭范围的最大数量级降低使最大聚集微生物突变增加了4倍。我们假设病原体物种形成和特有性随着隔离而增加，因为全球扩散距离通过类似于岛屿生物地理学理论的机制而减小。为了调查是否可以找到这种效果，我们分析了人类种群中出现了145种人畜共患病的情况，发现减少了体内寄生虫和粪便病原体扩散的定量估计大大提高了我们预测暴发地点的能力（方差增加了8％） ）。我们将详细讨论此分析的局限性，但是如果进一步的研究支持这些结果，