Evidence for adaptive responses to historic drought across a native plant species range

Abstract

As climatic conditions change, species will be forced to move or adapt to avoid extinction. Exacerbated by ongoing climate change, California recently experienced a severe and exceptional drought from 2011 to 2017. To investigate whether an adaptive response occurred during this event, we conducted a “resurrection” study of the cutleaf monkeyflower ( Mimulus laciniatus ), an annual plant, by comparing trait means and variances of ancestral seed collections (“pre‐drought”) with contemporary descendant collections (“drought”). Plants were grown under common conditions to test whether this geographically restricted species has the capacity to respond evolutionarily to climate stress across its range. We examined if traits shifted in response to the recent, severe drought and included populations across an elevation gradient, including populations at the low‐ and high‐elevation edges of the species range. We found that time to seedling emergence in the drought generation was significantly earlier than in the pre‐drought generation, a response consistent with drought adaptation. Additionally, trait variation in days to emergence was reduced in the drought generation, which suggests selection or bottleneck events. Days to first flower increased significantly by elevation, consistent with climate adaptation across the species range. Drought generation plants were larger and had greater reproduction, which was likely a carryover effect of earlier germination. These results demonstrate that rapid shifts in trait means and variances consistent with climate adaptation are occurring within populations, including peripheral populations at warm and cold climate limits, of a plant species with a relatively restricted range that has so far not shifted its elevation distribution during contemporary climate change. Thus, rapid evolution may mitigate, at least temporarily, range shifts under global climate change. This study highlights the need for better understanding rapid adaptation as a means for plant communities to cope with extraordinary climate events.

Selfing and Drought-Stress Strategies Under Water Deficit for Two Herbaceous Species in the South American Andes

“…A decrease in SLA may occur in response to drought in herbaceous leaves as a result of an increased investment in structural tissues allowing increased resistance to unfavorable environmental conditions (Maroco et al, 2000;Chaves et al, 2003). This trait has been widely used in experiments with different water availability regimes both for the comparison of populations within a species, and comparisons between two or more species since it plays an important role in linking plant carbon and water cycles (Marron et al, 2003;Xu and Zhou, 2008;Grassein et al, 2010;Lázaro-Nogal et al, 2015;Wellstein et al, 2017;Dickman et al, 2019). Therefore, our results suggest that S. hookeri, which had lower SLA than S. grahamii, appears to show greater dehydration tolerance than S. grahamii.…”

Review: Plant Eco-Evolutionary Responses to Climate Change: Emerging Directions

“…Using this approach, researchers can directly quantify evolutionary response to environmental change [314,315]. For example, studies resurrecting stored seeds, have shown rapid evolution of earlier flowering or seedling emergence following drought [80,[316][317][318] and warming [319], directional and/or stabilizing selection on flowering time in response to changes in precipitation patterns [80,320], rapid evolution of phenotypic plasticity in an invasive species [321], and evolution of herbicide resistance [322].…”

Plant adaptation to climate change—Where are we?

“…These shifts have involved local extinctions and population contractions at the warmer range edges as well as range expansions into historically cooler regions at poleward latitudes and upslope elevations (Angert et al, 2011;Chuang & Peterson, 2016;Sheth & Angert, 2018;Anderson & Wadgymar, 2020). Additionally, many species now emerge and reproduce significantly earlier in the year, which is likely a biological response to shortened winters, earlier onset of the growing season, and prolonged droughts (Cook et al, 2012;CaraDonna et al, 2014;Hamann et al, 2018;Wadgymar et al, 2018;Dickman et al, 2019).…”