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Local adaptation constrains drought tolerance in a tropical foundation tree
Journal of Ecology ( IF 5.3 ) Pub Date : 2020-01-08 , DOI: 10.1111/1365-2745.13354 Kasey E. Barton 1 , Casey Jones 1 , Kyle F. Edwards 2 , Aaron B. Shiels 3 , Tiffany Knight 4, 5, 6
中文翻译：
局部适应限制了热带基础树的耐旱性
更新日期：2020-01-08
Journal of Ecology ( IF 5.3 ) Pub Date : 2020-01-08 , DOI: 10.1111/1365-2745.13354 Kasey E. Barton 1 , Casey Jones 1 , Kyle F. Edwards 2 , Aaron B. Shiels 3 , Tiffany Knight 4, 5, 6
Affiliation
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- Plant species with broad climatic ranges might be more vulnerable to climate change than previously appreciated due to intraspecific variation in climatic stress tolerance. In tropical forests, drought is increasingly frequent and severe, causing widespread declines and altering community dynamics. Yet, little is known about whether foundation tropical trees vary in drought tolerance throughout their distributions, and how intraspecific variation in drought tolerance might contribute to their vulnerability to climate change.
- We tested for local adaptation in seedling emergence and establishment with a full‐factorial reciprocal transplant experiment including 27 populations and 109,350 seeds along a 3,500 mm precipitation gradient for a widespread tropical foundation tree, Metrosideros polymorpha , in Hawaii. To more precisely relate seedling performance to soil moisture, we conducted a complementary greenhouse experiment to test responses of the same focal populations to simulated drought.
- In the reciprocal transplant experiment, we observed significant variation among populations and sites in germination and seedling establishment rates. Overall, there was a significant link between historical rainfall of populations and their performance under current rainfall at the study sites consistent with local adaptation. In particular, populations from historically wet sites demonstrated lower germination rates in currently dry sites compared to wet field sites, while populations from historically dry sites germinated well across all sites, with particularly high germination in dry sites. In the greenhouse, seedlings from wet populations survived fewer days without water, and succumbed at wetter soil conditions than populations from historically dry sites, corroborating results from the field experiment.
- Synthesis . While climate change models project the greatest drying trends for historically dry areas in Hawaii, even moderate drying of wet sites could significantly reduce Metrosideros polymorpha recruitment given the sensitivity of seedlings to very slight changes in water regimes. Thus, although M. polymorpha demonstrates high seedling drought tolerance in some populations, providing evidence of resilience at the species‐scale, there are nonetheless vulnerable populations that will likely decline under climate change. Our approach demonstrates that even trees with high dispersal abilities can show significant clines in drought tolerance, and suggests that similar intraspecific variation might be an important consideration for other tropical foundational tree species.
中文翻译：
局部适应限制了热带基础树的耐旱性
- 由于种内气候胁迫耐受性的变化，具有较宽气候范围的植物物种可能比以前认为的更容易受到气候变化的影响。在热带森林中，干旱变得越来越频繁和严重，导致面积大幅度下降，并改变了社区动态。然而，人们对于基础热带树木在整个分布过程中的耐旱性是否存在变化以及种内抗旱性的种种变化如何导致其对气候变化的脆弱性知之甚少。
- 我们通过全要素互惠移植试验，在夏威夷广泛分布的热带基础树Metrosideros polymorpha，包括3,500 mm降水梯度下，包括27个种群和109,350粒种子，对幼苗的萌发和建立进行了局部适应性测试。为了更准确地将幼苗的生长性能与土壤水分相关联，我们进行了一项补充温室试验，以测试相同焦点种群对模拟干旱的响应。
- 在相互移植实验中，我们观察到种群和部位的发芽率和幼苗定植率存在显着差异。总体而言，研究地点的人口历史降雨与其在当前降雨条件下的表现之间存在重要联系，这与当地的适应一致。尤其是，与湿地相比，历史上较湿的地区的种群在当前干旱地区的发芽率要低，而历史上较干燥的地区的种群在所有地区的发芽都很好，而干旱地区的发芽率尤其高。在温室中，潮湿种群的幼苗在没有水的情况下存活的天数更少，并且在潮湿的土壤条件下比过去干旱地区的幼苗更容易死，这证实了田间试验的结果。
- 综合。尽管气候变化模型预测了夏威夷历史上干旱地区的最大干燥趋势，但即使湿地的适度干燥也可能显着降低多形都市拟南芥的吸收，因为幼苗对水分状况的微小变化非常敏感。因此，尽管M. polymorpha在某些种群中显示出较高的幼苗抗旱性，提供了物种规模上的复原力的证据，尽管如此，仍有一些脆弱种群在气候变化下可能会下降。我们的方法表明，即使具有高分散能力的树木也可以表现出明显的耐旱性，并表明相似的种内变异可能是其他热带基础树种的重要考虑因素。
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