Historical contingency in community assembly: insights from nectar yeasts and their interactions with bacteria, plants, and animals
Tad Fukami, Stanford
Ecological communities were once thought to tend towards a single climax state characterized by a deterministic species composition that can be predicted from environmental conditions. More recently, it is increasingly recognized that, even given the same environmental conditions, the way species affect one another through competition, predation, and other local interactions and their consequences for community structure can differ greatly depending on the history of community assembly, or the order and timing in which different species immigrate. With the increased recognition of such historical contingency in community assembly, known as priority effects, the fundamental challenge now is to understand how and when history matters to community assembly and when it affects not just community membership, but also the functioning of the whole community. In this talk, I will discuss recent and ongoing research addressing these questions using the fungal communities that develop in floral nectar as a model system. Species of yeasts that inhabit floral nectar engage in strong priority effects among one another and with the bacteria that are also found in nectar. Our work has shown that the strength of these priority effects is affected by a number of factors, including phylogenetic relatedness, niche similarity, and environmental variability. Furthermore, these priority effects in microbial community assembly can have functional consequences affecting plant reproduction and plant-pollinator mutualism.