Background/Question/Methods Despite being well-adapted to harsh conditions, dryland organisms are sensitive to shifts in climate patterns, especially precipitation regimes. In this context, species’ phenotypic plasticity can provide a buffer against climate changes and assist rapid adaptation. Many biocrust communities of the Colorado Plateau region are dominated by desert moss Syntrichia caninervis, a desiccation-tolerant bryophyte that contributes to ecosystem functions via carbon fixation, soil stabilization, water retention and dust capture. Bryophytes are known for their striking intra-specific variation, and S. caninervis appears to be a species morphologically variable along environmental gradients. We tested the plasticity of morphological traits of S. caninervis populations using two reciprocal transplant experiments with different time periods. We established a one-year reciprocal transplant focused only on populations of S. caninervis, and a three-year reciprocal transplant of biocrust communities with presence of S. caninervis. In both experiments the transplants were placed in 3 sites along an elevation and climate gradient in southeastern Utah. We analyzed the effects of populations source, the transplant site and time in the variation of the overall morphology and of specific traits. Results/Conclusions We summarized morphological trait data in a two-dimensional NMDS and conducted a PERMANOVA and homogeneity of dispersion test for each transplant experiment. The overall morphological trait variation in the one-year transplant study showed effects from the source populations (p=0.001), the transplant garden (p=0.001) and their interaction (p=0.006), and we found differences in dispersion between groups (p=0.004) attributed to the population of high-elevation transplanted to the low-elevation site. However, when we analyzed the variation in each trait, we only found source effects in the awn length (p=0.0001), below ground tissue length (p=0.018) and width (p=0.06), with no effects from the transplant gardens or their interaction. In the 3-years transplant study we found effects on the overall trait variation from both the source population (p=0.026) and the transplant gardens (p=0.001), with no interaction effects or group dispersion differences. We found no source or transplant effects on any of the measured traits. Our data suggests that S. caninervis has a rapid morphological trait response in novel climates attributed to phenotypic plasticity, and that longer exposure to new climates decreases the effects of their home environment. The high morphological variability and phenotypic plasticity shown by S. caninervis could play a key role in nonvascular plant adaptation under environmental change and have implications for drylands restoration and conservation.
