Data from: Plant-soil microbe feedbacks depend on distance and ploidy in a mixed cytotype population of Larrea tridentata

Premise of the study Theory predicts that mixed ploidy populations should
be short-lived due to strong fitness disadvantages for the rare ploidy.
However, mixed ploidy populations are common, suggesting that the fitness
costs for rare ploidies are counterbalanced by ecological benefits that
emerge when rare. We investigated whether differences in ecological
interactions with soil microbes help to maintain a tetraploid-hexaploid
population of Larrea tridentata (creosote bush) in the Sonoran Desert,
California, USA, where prior work documented ploidy-specific
root-associated microbes. Methods We used a plant-soil feedback (PSF)
experiment to test whether host-specific soil microbes can alter the
outcomes of intra-ploidy vs. inter-ploidy competition. Host-specific soil
microbes can build up over time; thus, distance from a host plant can
affect the fitness of nearby plants. Key results Seedlings grown in soils
from near plants of a different ploidy produced greater biomass relative
to seedlings grown in soils from near plants of the same ploidy. Moreover,
seedlings grown in soils from near plants of a different ploidy produced
greater biomass than those grown in soils from further away from plants of
a different ploidy. This suggests the ecological consequences of PSF may
facilitate the persistence of mixed ploidy populations. Conclusions This
is the first evidence, to our knowledge, consistent with plant-soil
microbe feedback as a viable mechanism to maintain the coexistence of
multiple ploidy levels in a single population.