Within-host adaptation alters priority effects within the tomato phyllosphere microbiome

In microbial community assembly, species that establish earlier often have an advantage. Here, the authors explore these priority effects in the tomato plant-associated microbiome, showing that experimental evolution selecting for host colonization alters priority effects among competitors. To predict the composition and function of ecological communities over time, it is essential to understand how in situ evolution alters priority effects between resident and invading species. Phyllosphere microbial communities are a useful model system to explore priority effects because the system is clearly spatially delineated and can be manipulated experimentally. We conducted an experimental evolution study with tomato plants and the early-colonizing bacterium species Pantoea dispersa, exploring priority effects when P. dispersa was introduced before, simultaneously with or after competitor species. P. dispersa rapidly evolved to invade a new niche within the plant tissue and altered its ecological interactions with other members of the plant microbiome and its effect on the host. Prevailing models have assumed that adaptation primarily improves the efficiency of resident species within their existing niches, yet in our study system, the resident species expanded its niche instead. This finding suggests potential limitations to the application of existing ecological theory to microbial communities.

Automated summary

In microbial community assembly, species that establish earlier often have an advantage. Experimental evolution selecting for host colonization alters priority effects among competitors in the tomato plant-associated microbiome. Understanding how in situ evolution alters priority effects is crucial for predicting the composition and function of ecological communities over time.