COS 139-3
Closely related plant species have similar soil fungal communities in their rhizosphere
Niche conservatism is the tendency for closely related taxa to be similar in conditions that allow them to persist, and understanding the drivers of niche conservatism is important for predicting responses to climate change, biological invasions, and ecological restoration. In our prior work, we have found that many angiosperm species performed better in closer relative's soils than in more distant relatives soils. However, what components of the soil drive this patterns are unknown. Here we examined potential drivers of phylogenetic signal on the soil niche, including soil bacteria and fungal communities. We collected soils from the rhizosphere of 14 grassland species that occur at Bodega Bay Marine Reserve, CA, USA, extracted whole-soil DNA using a bead-beating protocol, and conducted Terminal-Restriction Fragment Length Polymorphism (TRFLP) targeting 16S rDNA and the ITS region to quantify differences in the soil bacterial and fungal communities, respectively. To test for phylogenetic signal among plant species on soil microbial communities, we used a supermatrix analysis to estimate a maximum likelihood phylogeny, ordinated the microbial community data, and used Blomberg's K to test for phylogenetic signal on the ordination axes.
Results/Conclusions
Closely related plant species were significantly more similar in their rhizosphere fungal communities than expected by chance (K = 1.27, P = 0.009) and had fungal communities with similar OTU richness (K = 0.92, P = 0.07). Further, there was no phylogenetic signal on rhizosphere bacterial communities (P > 0.10). However, we saw evidence that some annual plant taxa (i.e. Gilia) did share similar bacterial communities, indicating that life history traits may influence the strength of the phylogenetic signal. These findings suggest that soil fungal communities could be one driver influencing phylogenetic signal on the plant-soil niche. Further work will test mechanisms that might govern this pattern. For example, greater rates of co-evolution with plants may lead to fungal communities displaying a greater degree of phylogenetic signal, when compared with bacterial soil associates. Understanding phylogenetic signal on components of the plant-soil niche has broad implications, for example suggesting that fungi from closely related plants could enhance restoration outcomes and that the absence of such fungi could limit responses to climate change.