Data from: Megafauna decline have reduced pathogen dispersal which may have increased emergent infectious diseases

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 km 2 d − 1 ). Similarly, the
extinctions led to a seven-fold reduction in the mean home ranges of
vector-borne pathogens (7.8–1.1km 2 ). To understand the impact of this,
we created an individualbased 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.

晚更新世巨型动物群（megafauna，定义为体重＞44.5千克的动物物种）灭绝事件，削弱了种子、营养物质乃至微生物与寄生虫的传播扩散过程。本研究基于体重尺度缩放关系（body-mass based scaling）与已灭绝、现存哺乳动物物种的分布范围地图，证实此类灭绝事件导致肠道传播微生物（如大肠杆菌（Escherichia coli））的移动量缩减近七倍，其传播速率从3.3平方千米/天降至0.5平方千米/天。与之类似，灭绝事件使媒介传播病原体（vector-borne pathogens）的平均家域范围缩减至原有水平的约七分之一，从7.8平方千米降至1.1平方千米。为阐明该影响的具体效应，我们构建了基于个体的模型（individual-based model）：当宿主家域范围下降一个数量级时，在20000年的模拟周期内，累计微生物的最大突变量可提升4倍。我们提出假说：病原体的物种形成乃至特有性会随隔离程度提升而增强，这是由于全球传播距离的缩减，其背后机制与岛屿生物地理学理论（island biogeography theory）相似。为验证该效应是否真实存在，我们分析了145种人畜共患病（zoonotic diseases）在人类群体中的暴发地点，结果发现：体外寄生虫（ectoparasites）与粪便传播病原体（fecal pathogens）传播能力下降的量化评估结果，可显著提升我们对暴发地点的预测能力（使模型解释的方差提升8%）。本分析存在一定局限性，我们将在文中详细讨论；但若后续研究验证了本研究结果，则可大致表明：巨型动物群灭绝后病原体传播能力的下降，可能提升了侵入人类群体的人畜共患病病原体的出现概率。