Ralph M. Parsons Laboratory for Environmental Science and Engineering, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, United States.
Physics of Living Systems, Department of Physics, Massachusetts Institute of Technology, Cambridge, United States.
Elife. 2022 Mar 15;11:e73948. doi: 10.7554/eLife.73948.
Microbial foraging in patchy environments, where resources are fragmented into particles or pockets embedded in a large matrix, plays a key role in natural environments. In the oceans and freshwater systems, particle-associated bacteria can interact with particle surfaces in different ways: some colonize only during short transients, while others form long-lived, stable colonies. We do not yet understand the ecological mechanisms by which both short- and long-term colonizers can coexist. Here, we address this problem with a mathematical model that explains how marine populations with different detachment rates from particles can stably coexist. In our model, populations grow only while on particles, but also face the increased risk of mortality by predation and sinking. Key to coexistence is the idea that detachment from particles modulates both net growth and mortality, but in opposite directions, creating a trade-off between them. While slow-detaching populations show the highest growth return (i.e., produce more net offspring), they are more susceptible to suffer higher rates of mortality than fast-detaching populations. Surprisingly, fluctuating environments, manifesting as blooms of particles (favoring growth) and predators (favoring mortality) significantly expand the likelihood that populations with different detachment rates can coexist. Our study shows how the spatial ecology of microbes in the ocean can lead to a predictable diversification of foraging strategies and the coexistence of multiple taxa on a single growth-limiting resource.
在斑块环境中，微生物觅食起着关键作用，其中资源被破碎成颗粒或口袋状嵌入在大基质中。在海洋和淡水系统中，与颗粒相关的细菌可以以不同的方式与颗粒表面相互作用：一些只在短暂的瞬间定植，而另一些则形成长期稳定的菌落。我们还不了解短期和长期定植者能够共存的生态机制。在这里，我们通过一个数学模型来解决这个问题，该模型解释了具有不同从颗粒上脱落率的海洋种群如何能够稳定共存。在我们的模型中，种群只有在颗粒上时才会生长，但也面临着捕食和下沉导致的死亡率增加的风险。共存的关键是这样一个想法，即从颗粒上的脱落既调节净增长又调节死亡率，但方向相反，在它们之间形成了一种权衡。虽然脱落缓慢的种群表现出最高的生长回报（即产生更多的净后代），但它们比脱落快的种群更容易遭受更高的死亡率。令人惊讶的是，波动的环境，表现为颗粒（有利于生长）和捕食者（有利于死亡率）的爆发，大大增加了具有不同脱落率的种群能够共存的可能性。我们的研究表明，海洋中微生物的空间生态学如何导致觅食策略的可预测多样化，以及在单一生长限制资源上多种分类群的共存。
