Branch Haley A, Moxley Dylan R, Angert Amy L
Ecology and Evolutionary Biology, Yale University, New Haven, CT, 06520, USA.
Biodiversity Research Centre and Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
New Phytol. 2024 Sep;243(6):2457-2469. doi: 10.1111/nph.19963. Epub 2024 Jul 17.
Characterizing physiological and anatomical changes that underlie rapid evolution following climatic perturbation can broaden our understanding of how climate change is affecting biodiversity. It can also provide evidence of cryptic adaptation despite stasis at higher levels of biological organization. Here, we compared evolutionary changes in populations of Mimulus cardinalis from historically different climates in the north and south of the species' range following an exceptional drought. We grew seeds produced from predrought ancestral plants alongside peak-drought descendants in a common glasshouse and exposed them to wet and dry conditions. Before the drought, northern ancestral populations expressed traits contributing to drought escape, while southern ancestral populations expressed drought avoidance. Following the drought, both regions evolved to reduce water loss and maintain photosynthesis in dry treatments (drought avoidance), but via different anatomical alterations in stomata, trichomes, and palisade mesophyll. Additionally, southern populations lost the ability to take advantage of wet conditions. These results reveal rapid evolution towards drought avoidance at an anatomical level following an exceptional drought, but suggest that differences in the mechanisms between regions incur different trade-offs. This sheds light on the importance of characterizing underlying mechanisms for downstream life-history and macromorphological traits.
描述气候扰动后快速进化背后的生理和解剖学变化，能够拓宽我们对于气候变化如何影响生物多样性的理解。这也能够提供证据，证明尽管在更高层次的生物组织层面处于停滞状态，但仍存在隐性适应。在此，我们比较了在一场异常干旱之后，来自该物种分布范围南北部历史上不同气候条件下的深红沟酸浆种群的进化变化。我们在一个普通温室中种植了干旱前祖先植物产生的种子以及干旱高峰期后代产生的种子，并将它们置于湿润和干燥条件下。在干旱之前，北部祖先种群表现出有助于干旱逃避的性状，而南部祖先种群表现出干旱回避。干旱之后，两个区域都进化出在干旱处理（干旱回避）中减少水分流失并维持光合作用的能力，但通过气孔、毛状体和栅栏叶肉中不同的解剖学改变来实现。此外，南部种群失去了利用湿润条件的能力。这些结果揭示了在一场异常干旱之后，在解剖学水平上朝着干旱回避的快速进化，但表明区域间机制的差异会导致不同的权衡。这阐明了描述下游生活史和宏观形态特征潜在机制的重要性。
