14 research outputs found
Quantifying the relative roles of selective and neutral processes in defining eukaryotic microbial communities
We have a limited understanding of the relative contributions of different processes that regulate microbial communities, which are crucial components of both natural and agricultural ecosystems. The contributions of selective and neutral processes in defining community composition are often confounded in field studies because as one moves through space, environments also change. Managed ecosystems provide an excellent opportunity to control for this and evaluate the relative strength of these processes by minimising differences between comparable niches separated at different geographic scales. We use next-generation sequencing to characterize the variance in fungal communities inhabiting adjacent fruit, soil and bark in comparable vineyards across 1000 kms in New Zealand. By compartmentalizing community variation, we reveal that niche explains at least four times more community variance than geographic location. We go beyond merely demonstrating that different communities are found in both different niches and locations by quantifying the forces that define these patterns. Overall, selection unsurprisingly predominantly shapes these microbial communities, but we show the balance of neutral processes also have a significant role in defining community assemblage in eukaryotic microbes
A niche remedy for the dynamical problems of neutral theory
We demonstrate how niche theory and Hubbell's original formulation of neutral
theory can be blended together into a general framework modeling the combined
effects of selection, drift, speciation, and dispersal on community dynamics.
This framework connects many seemingly unrelated ecological population models,
and allows for quantitative predictions to be made about the impact of niche
stabilizing and destabilizing forces on population extinction times and
abundance distributions. In particular, the existence of niche stabilizing
forces in our blended framework can simultaneously resolve two major problems
with the dynamics of neutral theory, namely predictions of species lifetimes
that are too short and species ages that are too long.Comment: 47 pages, 4 figures, Accepted to Theoretical Ecolog