Abstract
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.
Highlights
Instituto de Biociências, Departamento de Ecologia, Universidade Estadual Paulista (UNESP), Keyword – Emergent infectious disease, Extinctions, Megafauna
We estimate that the mean global home range of a generalist ectoparasite (Equation 2 – the average home range of all mammal species in its ecosystem) averages ~8 km2 (Table 1)
The decreases were large in South America, where mean home range decreased over two orders of magnitude in the south of the continent since all 26 local mammal species >1,000 kg went extinct (Sandom et al 2014)
Summary
Instituto de Biociências, Departamento de Ecologia, Universidade Estadual Paulista (UNESP), Keyword – Emergent infectious disease, Extinctions, Megafauna. We hypothesize that pathogen speciation and 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%). We ask whether changes in microbe dispersal distances as a consequence of the megafauna extinctions impacted the emergence of zoonotic infectious diseases. A fast-acting, highly virulent disease would quickly kill off the sparse hunter-gather population before the disease had a chance to spread, killing off the disease
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
