COS 57-4 - Geographic trends in the niche space of microbial consortia within the northern pitcher plant (Sarracenia purpurea)

Tuesday, August 8, 2023

8:45 AM – 9:00 AM PDT

Location: B119

Presenting Author(s)

GC

Grace A. Cagle

Postdoctoral Researcher
University of Wisconsin - Madison, United States

Coauthor(s)

AM

Alicia McGrew

Post-doctoral Fellow
Institute for Watershed Studies, Western Washington University
Bellingham, Washington, United States
BB

Benjamin Baiser

Associate Professor
Department of Wildlife Ecology and Conservation, University of Florida
Gainesville, FL, United States
SR

Sydne Record

Associate Professor
Department of Wildlife, Fisheries, and Conservation Biology, University of Maine, Maine, United States
DG

Dominique Gravel

University of Sherbrooke, Quebec, Canada
TP

Timothée Poisot, PhD

Associate Professor
Département de Sciences Biologiques, Université de Montréal, Quebec, Canada
NG

Nicholas J. Gotelli

University of Vermont
Burlington, Vermont, United States
Leonora S. Bittleston

Assistant Professor
Boise State University
Boise, Idaho, United States
EY

Erica Young

University of Wisconsin - Milwaukee, United States
SG

Sarah Gray

University of Fribourg, Switzerland

Co-Author(s)

ZF

Zachary B. Freedman

Assistant Professor
University of Wisconsin-Madison, United States

Abstract: Many of the important functions performed by microorganisms are emergent properties of complex associations among microbial taxa and their environment. At large (e.g., continental) spatial scales, these associations may be detectable through species co-occurrence relationships, which can also reflect niche processes that drive coexistence and the maintenance of diversity within biological communities. For example, network modularity, in which distinct subsets of a network are more connected with each other than the rest of the network, has been suggested to represent niche space. However, whether there are patterns of microbial coexistence across large spatial scales, and the ecological processes underlying bacterial coexistence is not well understood. To determine whether microbiomes exhibit spatial variation in cooccurrence dynamics, and the ecological processes underlying these dynamics, we conducted a continental-scale network analysis of the bacterial inhabitants of the northern Pitcher Plant (Sarracenia purpurea) pitchers. The microecosystem supported by S. purpurea is an ideal system to investigate mechanisms of microbial coexistence, as it is a model system in community ecology and exhibits a similar form across its continental-scale range. We assessed the microbiomes of 108 S. purpurea pitchers spanning their N-S range in North America using a single co-occurrence network that was constructed using an ensemble approach. The network exhibited a scale-free and modular structure indicative of a non-random pattern. Our analysis revealed one of 11 total modules was significantly and negatively correlated with latitude, indicating a niche that may be unique to low-latitude pitchers. The other modules were relatively consistent across the range of S. purpurea and not significantly associated with 18 pitcher and environmental variables we collected, potentially indicating conserved functionality within the microbiome. The phylogenetic relatedness of taxa within modules was significantly greater than expected, supporting our interpretation of modules as representative of niche space. We further identified that ‘hub’ taxa, defined as those with high centrality scores, tended to be hubs across the range of the plant, indicating these species may have a high impact on the system across its range. Recurring modules and hub taxa in the S. purpurea microbiome are consistent with other work in this model ecosystem that suggest the plant plays an active role in modifying its internal environment. In summary, these results reveal that microbial co-occurrences in the model system S. purpurea are largely consistent across the range of the plant and are subjected to selective forces that drive evolutionary relatedness amongst co-occurring taxa.