Abstract Detail

Ecology

Kandlikar, Gaurav [1], Yan, Xinyi [2].

A meta-analysis of microbially-mediated stabilization and fitness differences among plants.

Dynamic feedbacks between plant species and their soil microbial communities play an important role in shaping a variety of processes in plant communities, including the maintenance of plant species diversity. Recent theoretical advances have shown that evaluating the net effects of such plant-soil feedbacks (PSFs) on plant coexistence requires comparing the strength of their stabilizing or destabilizing effects (via driving negative or positive frequency dependence, respectively), to the frequency-independent fitness difference they simultaneously generate among plants. Most empirical studies of PSF have tested only for stabilizing or destabilizing effects of soil microbes, with previous meta-analyses showing that such feedbacks often generate negative frequency dependent dynamics that should promote plant diversity. However, very few empirical studies have compared the (de)stabilizing effects of PSFs to the fitness differences they mediate, and the net effects of these feedbacks on plant coexistence remain unclear. Here we present a meta-analysis to evaluate the relative strength of microbially mediated fitness differences and microbially mediated (de)stabilization.
We screened 69 papers from a published meta-analysis dataset and an additional 330 papers published since, to select studies that factorially grew plants in soils conditioned by conspecifics, by a heterospecific, and in an unconditioned (reference) inoculum. We identified 40 qualified studies, which used either autoclaved soil (n=21) or live soil collected from the field (n = 19) as the unconditioned reference. Among studies with live field soil reference (58 species pairs), the effect of PSFs is on average stabilizing (mean = 0.24, CI = (0.04, 0.44), p = 0.016), consistent with the result of a recent meta-analysis. Moreover, we also found that PSFs also generate significant fitness differences among species pairs (mean = 0.64, CI = (0.41, 0.87), p<0.0001). In 22% of the pairs, we found strong evidence that soil microbes generate larger fitness differences that overwhelm their stabilizing or destabilizing effect and favor exclusion. In the remaining pairs, the 95% confidence interval of microbially mediated stabilization and fitness difference overlapped each other, indicating that PSFs generate net neutral dynamics among them. These preliminary results reveal the tendency of PSFs to generate substantial fitness differences that often undermine their stabilizing effects, emphasizing the necessity to simultaneously consider both processes. Our work also highlights the need for empirical studies to include carefully selected reference treatments for calculating microbially mediated fitness differences and thereby inferring the total effects of soil microbes on plant diversity.

1 - University Of Missouri, Biological Sciences, 105 Tucker Hall , Columbia, MO, 65211, United States
2 - University of Texas, Austin, Integrative Biology

Keywords:
Species coexistence
plant-microbe interactions
competition
plant-soil interactions.

Presentation Type: Oral Paper
Session: ECO4, Ecology: Community Assemblages, Succession and Marcescence
Location: /
Date: Thursday, July 22nd, 2021
Time: 11:15 AM(EDT)
Number: ECO4006
Abstract ID:591
Candidate for Awards:None