Evolution of shade tolerance is associated with attenuation of shade avoidance and reduced phenotypic plasticity in North American milkweeds
Evolution of shade tolerance is associated with attenuation of shade avoidance and reduced phenotypic plasticity in North American milkweeds
复制标题
北美马利筋耐荫性的进化与避荫能力的减弱和表型可塑性的降低有关
DOI：
10.1002/ajb2.1732
复制
发表时间：
2021
影响因子：
3
通讯作者：
Agrawal, Anurag A.
中科院分区：
文献类型：
--
作者：
Coverdale, Tyler C.;Agrawal, Anurag A.
Premise光条件和光捕捉策略之间的不匹配会降低植物的表现，防止新生境的定居。虽然光捕捉策略在亲缘关系密切的物种中趋于高度保守，但许多植物品系都发生了从遮荫到非遮荫生境的进化转变(反之亦然)。方法我们结合系统发育学方法与田间和温室实验来研究北美乳草(Asclepias)捕光策略的进化限制，并确定这种喜日分支中遮荫生境的定居是否与遮荫回避反应的可塑性降低和减弱有关。生境之间的进化转变表现出强烈的方向性偏向，从全日照到遮荫生境的转变发生的频率至少是相反转变的三倍。在田间和温室实验中，阳光树种通过增加节间长度、高度和比叶面积来响应遮荫，这与遮荫反应一致；成对遮荫的树种总体上表现出可塑性降低，只有一个性状(比叶面积)对实验阴影做出反应。结论我们的结果表明，黄花多次在遮荫环境中定居，采用不同于祖先(可能是避荫)策略的捕光策略，包括对不同光照条件的可塑性普遍减弱。这种模式支持了这样一种观点，即遮荫回避和耐受代表着在不同类型遮荫下最大化表现的不同进化策略。
PremiseMismatches between light conditions and light‐capture strategy can reduce plant performance and prevent colonization of novel habitats. Although light‐capture strategies tend to be highly conserved among closely related species, evolutionary transitions from shaded to unshaded habitats (and vice versa) occur in numerous plant lineages.MethodsWe combined phylogenetic approaches with field and greenhouse experiments to investigate evolutionary constraints on light‐capture strategy in North American milkweeds (genusAsclepias) and to determine whether colonization of shaded habitats in this heliophilic clade is associated with reduced plasticity and attenuation of the shade avoidance response.ResultsColonization of shaded habitats has occurred at least 10 times in this genus, including at least once in each major North American clade. Evolutionary transitions between habitats exhibit strong directional bias, with shifts from full‐sun to shaded habitats occurring at least three times as often as the opposite transition. In field and greenhouse experiments, sun species responded to shade by increasing internode length, height, and specific leaf area, consistent with the shade avoidance response; paired shade species exhibited reduced plasticity overall, and only one trait (specific leaf area) responded to experimental shade.ConclusionsOur results suggest that milkweeds colonized shaded environments multiple times using a light‐capture strategy distinct from the ancestral (putatively shade avoidant) strategy, including a general attenuation of plasticity in response to variable light conditions. This pattern bolsters the notion that shade avoidance and tolerance represent divergent evolutionary strategies for maximizing performance under qualitatively different types of shade.