Experimental drought reduces genetic diversity in the grassland foundation species Bouteloua eriopoda

Abstract

Understanding the resistance and resilience of foundation plant species to climate change is a critical issue because the loss of these species would fundamentally reshape communities and ecosystem processes. High levels of population genetic diversity may buffer foundation species against climate disruptions, but the strong selective pressures associated with climatic shifts may also rapidly reduce such diversity. We characterized genetic diversity and its responsiveness to experimental drought in the foundation plant, black grama grass (Bouteloua eriopoda), which dominates many western North American grasslands and shrublands. Previous studies suggested that in arid ecosystems, black grama reproduces largely asexually via stolons, and thus is likely to have low genetic variability, which might limit its potential to respond to climate disruptions. Using genotyping-by-sequencing, we demonstrated unexpectedly high genetic variability among black grama plants in a 1 ha site within the Sevilleta National Wildlife Refuge in central New Mexico, suggesting some level of sexual reproduction. Three years of experimental, growing season drought reduced black grama survival and biomass (the latter by 96%), with clear genetic differentiation (higher FST) between cohorts succumbing to drought and those remaining alive. Reduced genetic variability in the surviving cohorts in drought plots indicated that the experimental drought had forced black grama populations through selection bottlenecks. These results suggest that foundation grass species, such as black grama, may experience rapid evolutionary change if future climates include more severe droughts.

Soil precipitation legacies influence intraspecific plant–soil feedback

“…Therefore, plant-soil feedback driven changes in population structure may magnify the negative effect of drought on P. virgatum productivity. While previous work has found that drought may cause rapid evolutionary change in a foundational grass (Whitney et al 2019), the genotype-dependent soil legacies we found suggest that precipitation and soil microbes jointly drive evolution in P. virgatum populations. Subsequent changes in the microbial community caused by microbially driven changes in P. virgatum populations sets up the potential for strong ecoevolutionary dynamics in this system.…”

Extreme drought has limited effects on soil seed bank composition in desert grasslands

“…For each site, all plots within a block (including the control) were located at least 5 m apart, and trenched to 20 cm and surrounded by an aluminum flashing barrier to hydrologically isolate them from the adjacent soil. The most significant environmental artifacts of these shelters are a 0.4°C increase in temperature (Whitney et al, 2019), and 5%-10% reduction in light due to the polycarbonate roofing material used, which is still above saturating light levels in this system.…”

Elevated mutation and selection in wild emmer wheat in response to 28 years of global warming

“…However, these valuable genetic resources are found to be highly underconserved (18), and concerns for losing these genetic resources are mounting (19). Also, many studies have revealed increasing threats for crop wild relatives in natural populations, particularly from global warming (1, 20, 21), but few studies have characterized genetic responses of wild relative populations to the threats of global warming (22–24).…”