Intraspecific functional differentiation suggests local adaptation to long‐term climate change in a calcareous grassland

Abstract

Summary1. Populations of the common perennial herb Plantago lanceolata L. have been exposed to nearly two decades of summer drought at the Buxton Climate Change Experiment (BCCIL), a controlled manipulation of climate factors in a species-rich limestone grassland in northern England. 2. We used a common garden approach to test for evidence of selection for different suites of functional traits in P. lanceolata populations exposed to chronic summer drought and across a soil depth gradient. 3. The main axis of functional variation reflected a trade-off between reproductive and vegetative allocation, consistent with drought avoidance and competitive strategies, respectively. Avoidance strategies were more prominent in droughted populations, whereas competitive strategies were more prominent in populations from control treatments. Treatment differences were more pronounced in shallower soils. Deeper soils in both control and drought treatments promoted functional differentiation associated with competitive strategies, suggesting that selective pressures imposed by different climate treatments are modified by fine-scale edaphic heterogeneity. 4. Synthesis. Results suggest that population-level shifts can be a mechanism of resistance to local climate-induced extinction. Trait differentiation with respect to fine-scale variation in soil depth suggests that edaphic heterogeneity fosters high local genetic diversity, which provides a range of local phenotypes upon which drought-based selection may act.

Severe effects of long-term drought on calcareous grassland seed banks

“…Specifically, we found that both vegetation and seed bank showed no response to supplemental summer rainfall. In response to drought, the previously reported significant reduction in drought-sensitive species associated with moist soils 26,29 was mirrored in the seed bank, although the effect of drought was greater on seed banks than on above-ground vegetation; 25,26 species of moist soils, such as C. panicea and P. erecta, simply disappeared from the seed bank after 14 years of drought. In contrast, C. rotundifolia and H. pulchrum, species whose seed banks showed significant responses to drought, did not show any responses above-ground in a previous analysis of ours.…”

“…26 Sometimes, the response of the soil seed bank to climate variables may simply reflect the responses of the vegetation. In this case, the NMDS ordination suggests that compositional changes, at the community level, involving drought-resistant and sensitive species, species characteristic of wetter sites, 26 and perhaps even the local genetic differentiation recorded in some species above-ground 25 might be mirrored in the seed bank. Specifically, we found that both vegetation and seed bank showed no response to supplemental summer rainfall.…”

“…Above-ground studies have revealed that plant responses to altered precipitation regimes are mediated by micro-topographic or micro-environmental effects. [25][26][27] Specifically, in calcareous grasslands resistance is linked to community reorganization at the microsite level facilitated by soil depth. 26 For example, at the Buxton Climate Change Experiment (England, UK), some species have moved to areas of deeper soil while others have moved to shallower soil in response to long-term precipitation treatments.…”

Plasticity in plant functional traits is shaped by variability in neighbourhood species composition

“…Studies on invasive plant species and biodiversity manipulation experiments show potential for fast local adaptation to abiotic and biotic components of the ecosystem (Callaway et al ., ; Lankau, ; Ravenscroft et al ., ; Zuppinger‐Dingley et al ., ). Our study shows a similar pattern in natural grassland systems, where variability in species composition of immediate neighbours results in an enhanced ability to modify morphology in response to neighbour identity.…”

Genetic differentiation and plasticity interact along temperature and precipitation gradients to determine plant performance under climate change

“…to face climate change in situ (e.g. Davis & Shaw 2001;Malcolm et al 2002;Thomas et al 2004;Loarie et al 2009;Bullock et al 2012;Ravenscroft, Fridley & Grime 2014).…”