Biogeographic Patterns Between Bacterial Phyllosphere Communities of the Southern Magnolia (Magnolia grandiflora) in a Small Forest

Abstract

The phyllosphere presents a unique system of discrete and easily replicable surfaces colonized primarily by bacteria. However, the biogeography of bacteria in the phyllosphere is little understood, especially at small to intermediate scales. Bacterial communities on the leaves of 91 southern magnolia (Magnolia grandiflora) trees 1-452 m apart in a small forest plot were analyzed and fragments of the 16S ribosomal RNA (rRNA) gene sequenced using the Illumina platform. Assemblages were dominated by members of the Alphaproteobacteria, Bacteroidetes, and Acidobacteria. Patterns in community composition were measured by both relative abundance (theta) and presence-absence (Jaccard) dissimilarity metrics. Distance-based Moran's eigenvector map analyses of the distance-decay relationship found a significant, positive relationship between each dissimilarity metric and significant eigenfunctions derived from geographic distance between trees, indicating trees that were closer together had more similar bacterial phyllosphere communities. Indirect gradient analyses revealed that several environmental parameters (canopy cover, tree elevation, and the slope and aspect of the ground beneath trees) were significantly related to multivariate ordination scores based on relative bacterial sequence abundances; however, these relationships were not significant when looking at the incidence of bacterial taxa. This suggests that bacterial growth and abundance in the phyllosphere is shaped by different assembly mechanisms than bacterial presence or absence. More broadly, this study demonstrates that the distance-decay relationship applies to phyllosphere communities at local scales, and that environmental parameters as well as neutral forces may both influence spatial patterns in the phyllosphere.

Host-associated microbiomes are predicted by immune system complexity and climate

“…Do abiotic conditions have stronger effects on ectotherms compared with endothermic hosts? Are microbial therapies effective [17,[51][52][53]?…”

“…The compiled dataset is comprised of 15,790 samples from 51 studies including all host-associated data from the Earth Microbiome Project [4] and includes 16 host classes (Fig. 3) from plants to corals to vertebrates (including 4 human populations; Additional file 1: Figure S4, [9,[50][51][52][53][54][55][56][57][58]).…”

Patterns of variation in diversity of the Mississippi river microbiome over 1,300 kilometers

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“…Prior to classification, sequences nearly identical (<2 bp differences) to one another were merged [26], and potential chimeras identified using UCHIME [29] and removed. Taxonomic classification of sequences was performed using the Greengenes database [30], a database more suitable for classifying 16S rRNA sequences than the SILVA database used to align sequences [31].…”

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