Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, Minnesota, 55108, USA.
Ecology. 2019 Nov;100(11):e02836. doi: 10.1002/ecy.2836. Epub 2019 Aug 30.
Communities of free-living organisms are shaped by processes operating within and among patches of habitat, whereas pathogen communities are shaped by analogous processes operating within and among hosts. Resource competition (R*) theory can describe dynamics within patches or hosts, and metacommunity dynamics describe competition-colonization trade-offs, extinction debts, and superinfection. However, models at this broader scale often assume instantaneous competitive exclusion in co-inhabited patches or co-infected hosts. Impacts of more gradual competitive exclusion on the abundance, distribution, and diversity of species are less clear. Here, we nest a general resource competition model within a metacommunity framework and manipulate the relative timescales for processes operating within and among patches/hosts. We focus on superinfection in pathogen communities. We compare cases where transmission depends on infection prevalence vs. the abundance of pathogens within hosts. Surprisingly, slowing the relative pace of competitive exclusion within hosts can decrease infection prevalence of the inferior competitor and increase prevalence of the superior competitor, depending on transmission and virulence. Slower within-host dynamics reduce the abundance of both pathogens within hosts and promote diversity at multiple scales: co-infections within individual hosts and co-occurrence in the host population. These results highlight surprising feedbacks that can emerge across scales and reinforce the rich cross-scale connections between community and disease ecology.
自由生活生物群落是由在生境斑块内和之间起作用的过程塑造的，而病原体群落则是由在宿主内和之间起作用的类似过程塑造的。资源竞争（R*）理论可以描述斑块或宿主内的动态，而集合种群动态描述了竞争-定殖权衡、灭绝债务和超感染。然而，在更广泛的尺度上的模型通常假设在共同栖息的斑块或共同感染的宿主中瞬间的竞争排斥。更渐进的竞争排斥对物种的丰度、分布和多样性的影响则不太清楚。在这里，我们在集合种群框架内嵌套一个通用的资源竞争模型，并操纵在斑块/宿主内和之间起作用的过程的相对时间尺度。我们专注于病原体群落中的超感染。我们比较了传输依赖于感染流行率与宿主内病原体丰度的情况。令人惊讶的是，根据传输和毒力，减缓宿主内竞争排斥的相对速度可以降低劣势竞争者的感染流行率，并增加优势竞争者的流行率。较慢的宿主内动态减少了宿主内两种病原体的丰度，并促进了多个尺度的多样性：单个宿主内的共感染和宿主种群中的共现。这些结果突出了可以在多个尺度上出现的惊人反馈，并加强了群落和疾病生态学之间丰富的跨尺度联系。
