Meng H, Wei X, Franklin S B, Wu H, Jiang M
Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, Hubei, China.
University of Chinese Academy of Sciences, Beijing, China.
Plant Biol (Stuttg). 2017 Jul;19(4):552-561. doi: 10.1111/plb.12564. Epub 2017 Apr 3.
Intraspecific trait variation and trait-climate relationships are crucial for understanding a species' response to climate change. However, these phenomena have rarely been studied for tree species. Euptelea pleiospermum is a relict tree species with a wide distribution in China that offers a novel opportunity to examine such relationships. Here, we measured 13 leaf traits of E. pleiospermum in 20 sites across its natural distribution in China. We investigated the extent of trait variation at local and regional scales, and developed geographic and climate models to explain trait variation at the regional scale. We documented intraspecific trait variation among leaf traits of E. pleiospermum at local and regional scales. Five traits exhibited relatively high trait variation: leaf area, leaf density and three leaf economic traits (leaf dry matter content, specific leaf area [SLA] and leaf phosphorus concentration). Significant trait-geography correlations were mediated by local climate. Most leaf trait variation could be explained (from 24% to 64%) by geographic or climate variables, except leaf width, leaf thickness, leaf dry matter content and leaf length-width ratio. Latitude and temperature were the strongest predictors of trait variation throughout the distribution of E. pleiospermum in China, and temperature explained more leaf trait variation than precipitation. In particular, we showed that leaves had longer petiole lengths, higher SLA and lower densities in northern E. pleiospermum populations. We suggest that northern E. pleiospermum populations are adapting to higher latitudinal environments via high growth rate (higher SLA) and low construction investment strategies (lower leaf densities), benefitting northern migration. Overall, we demonstrate that intraspecific trait variation reflects E. pleiospermum response to the local environment. We call for consideration of intraspecific trait variation to examine specific climate response questions. In addition, provenance experiments using widely distributed species are needed to separate trait variation resulting from genetic differentiation and plastic responses to environmental change.
种内性状变异和性状与气候的关系对于理解一个物种对气候变化的响应至关重要。然而，这些现象在树种中很少得到研究。领春木是一种在中国广泛分布的孑遗树种，为研究此类关系提供了新的契机。在此，我们在中国领春木自然分布区的20个地点测量了其13个叶片性状。我们调查了局部和区域尺度上性状变异的程度，并建立了地理和气候模型来解释区域尺度上的性状变异。我们记录了中国领春木局部和区域尺度上叶片性状的种内性状变异。五个性状表现出相对较高的性状变异：叶面积、叶密度和三个叶片经济性状（叶片干物质含量、比叶面积[SLA]和叶片磷浓度）。显著的性状与地理相关性由局部气候介导。除了叶宽、叶厚、叶片干物质含量和叶长宽比外，大多数叶片性状变异可以由地理或气候变量解释（从24%到64%）。纬度和温度是中国领春木整个分布区性状变异的最强预测因子，温度比降水解释了更多的叶片性状变异。特别是，我们发现中国北方领春木种群的叶片叶柄更长、SLA更高且密度更低。我们认为，中国北方领春木种群正通过高生长率（更高的SLA）和低构建投资策略（更低的叶密度）适应更高纬度的环境，这有利于向北迁移。总体而言，我们证明种内性状变异反映了领春木对当地环境的响应。我们呼吁在研究特定气候响应问题时考虑种内性状变异。此外，需要利用广泛分布的物种进行种源实验，以区分由遗传分化和对环境变化的可塑性响应导致的性状变异。
