Citation: Pastore, A. I., and B. P. Scherer. 2016. Changes in community phylogenetic structure in a North American forest chronosequence. Ecosphere 7(12):e01592. 10.1002/ecs2.1592Abstract. Several studies of succession in tropical and subtropical climates include phylogenetic analyses of the plant communities; the majority of these studies find a shift from more closely related to less closely related assemblages over succession. It has been suggested that this pattern indicates a shift from abiotic to biotic filters structuring communities over time, but there is considerable debate surrounding this interpretation. Conducting analyses for multiple components of plant assemblages can provide insight into the processes structuring communities. Here, we present community phylogenetic analyses of a deciduous forest chronosequence for three community components: standing vegetation, seed bank, and vegetation regenerated after small-scale disturbance. We constructed a phylogeny from 228 taxa present in the community data of a chronosequence obtained from previously published research. In the standing vegetation, we found a shift from more closely related to less closely related vegetation over the chronosequence. These results are consistent with other studies of chronosequences in tropical forests, lending support to the ubiquity of such shifts in relatedness over succession under different climatic conditions. However, the seed bank and vegetation regenerated after small-scale disturbance showed no consistent pattern with stand age, suggesting recruits are experiencing different forces than surrounding vegetation. These phylogenetic analyses of seed banks and vegetation regenerated after small-scale disturbance over a chronosequence provide additional evidence into the mechanisms driving forest succession.

Bacterial communities associated with plant propagules remain understudied, despite the opportunities that propagules represent as dispersal vectors for bacteria to new sites. These communities may be the product of a combination of environmental in uence and inheritance from parent to offspring. The relative role of these mechanisms could have signi cant implications for our understanding of plantmicrobe interactions. We studied the correlates of microbiome community similarities across an invasion front of red mangroves (Rhizophora mangle L.) in Florida, where the species is expanding northward. We collected georeferenced propagule samples from 110 individuals of red mangroves across 11 populations in Florida and used 16S rRNA gene (iTag) sequencing to describe their bacterial communities. We found no core community of bacterial Amplicon Sequence Variants (ASVs) across the Florida range of red mangroves, though there were some ASVs shared among individuals within most populations. Populations differed signi cantly as measured by Bray-Curtis dissimilarity, but not Unifrac distance. We generated data from 6 microsatellite loci from 60 individuals across 9 of the 11 populations. Geographic distance was correlated with beta diversity, but genetic distance was not. We conclude that red mangrove propagule bacterial communities are likely in uenced more by local environmental acquisition than by inheritance.

Plant-associated microbial communities may be important sources of functional diversity and genetic variation that influence host evolution. Bacteria provide benefits for their hosts, yet in most plant systems we know little about their taxonomic composition or variation across tissues and host range. Red Mangrove (Rhizophora mangle L.) is a vital coastal plant species that is currently expanding poleward and with it, perhaps, its microbiome. We explored variability in bacterial communities across tissues, individuals, and populations. We collected samples from six sample types from 5–10 individuals at each of 3 populations and used 16S rRNA gene (iTag) sequencing to describe their bacterial communities. Core community members and dominant bacterial classes were determined for each sample type. Pairwise PERMANOVA of Bray-Curtis dissimilarity and Indicator Species Analysis revealed significant differences in bacterial communities between sample types and populations. We described the previously unexplored microbiome of the reproductive tissues of R. mangle. Populations and most sample types were associated with distinct communities. Bacterial communities associated with R. mangle are influenced by host geography and sample type. Our study provides a foundation for future work exploring the functional roles of these microbes and their relevance to biogeochemical cycling.

Bacterial communities associated with plant propagules remain understudied, despite the opportunities that propagules represent as dispersal vectors for bacteria to new sites. These communities may be the product of a combination of environmental influence and inheritance from parent to offspring. The relative role of these mechanisms could have significant implications for our understanding of plant-microbe interactions. We studied the correlates of microbiome community similarities across an invasion front of red mangroves (Rhizophora mangle L.) in Florida, where the species is expanding northward. We collected georeferenced propagule samples from 110 individuals of red mangroves across 11 populations in Florida and used 16S rRNA gene (iTag) sequencing to describe their bacterial communities. We found no core community of bacterial Amplicon Sequence Variants (ASVs) across the Florida range of red mangroves, though there were some ASVs shared among individuals within most populations. Populations differed significantly as measured by Bray-Curtis dissimilarity, but not Unifrac distance. We generated data from 6 microsatellite loci from 60 individuals across 9 of the 11 populations. Geographic distance was correlated with beta diversity, but genetic distance was not. We conclude that red mangrove propagule bacterial communities are likely influenced more by local environmental acquisition than by inheritance.