Spatial controls on eco-evolutionary processes in microbial communities

Microorganisms are the most biodiverse life forms on our planet, yet we know little about the spatial processes underlying their ecology and evolution. Here, we highlight the importance of two spatial processes that act on individual cells – spatial intermixing of different populations and mechanical cell shoving during growth – to improve our understanding of microbial eco-evolutionary dynamics. Using an individual-based model, we show that the coexistence between slow- and fast-growing populations becomes highly constrained under two conditions: when the slow- and fast-growing populations are highly spatially intermixed and when the ability to shove other cells (both conspecific and heterospecific) is weak. The potential for evolution through plasmid-mediated horizontal gene transfer between slow- and fast- growing populations also becomes restricted in the same scenario. Our modeling highlights that ecological constraints can dampen evolutionary opportunities within microbial communities due to variation in spatial intermixing and mechanical shoving at the cellular scale.

Methods
Data are all generated using Cellmodeller.

微生物是地球上生物多样性最为丰富的生命形式，但我们对其生态学与演化背后的空间过程仍知之甚少。在此我们着重阐明两种作用于单个细胞的空间过程的重要意义——不同种群的空间混合，以及生长过程中的细胞机械推挤——以期深化我们对微生物生态演化动态的认知。通过基于个体的模型（individual-based model），我们发现慢生长种群与快生长种群的共存会在两种条件下受到显著限制：一是快慢种群发生高度空间混合，二是细胞（同种与异种）的推挤能力较弱。在相同场景下，通过质粒介导的水平基因转移（horizontal gene transfer）实现演化的潜力也会受到限制。本模型研究表明，由于细胞尺度上的空间混合与机械推挤存在差异，生态约束会抑制微生物群落内的演化机遇。

方法
所有数据均通过Cellmodeller生成。