Abstract In the African tropical dry woodlands, very few woody species are able to thrive both on Macrotermes termite mounds and in the surrounding matrix. Dalbergia boehmii is one such broad-niched species. In a previous study, populations on and off mounds were found to have different functional trait values. Here, in two reciprocal transplant experiments, both in situ and ex situ (pot experiment) we test whether the plants from mounds and from the matrix have evolved genetically divergent traits and are locally adapted (edaphic ecotypes), or whether trait differences arise from phenotypic plasticity. Growth, survival and morphological functional leaf traits were monitored. Seedling survival did not differ between plants of different origins and habitats. No constitutive difference or no heritable features were found between the plants of the two origins. However, functional traits varied between habitats in the in situ experiment, with higher specific leaf area (SLA) and lower leaf dry matter content values on termite mounds, indicating plastic response. The magnitude of the plastic response was larger in situ compared to the pot experiment, suggesting that other ecological factors, in addition to soil, drive trait plasticity. We conclude that the broad niche of the species is due to its ability to express adaptive phenotypic plasticity, not to locally adapted genotypes.

中文翻译：

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表型可塑性，而不是生态型分化，解释了非洲干旱林地树种的广泛生态位

摘要 在非洲热带干旱林地中，很少有木本物种能够在大白蚁白蚁丘和周围基质中茁壮成长。Dalbergia boehmii 就是这样一种广泛的物种。在之前的一项研究中，发现土丘内外的种群具有不同的功能特征值。在这里，在两个相互移植实验中，原位和异地（盆栽实验）我们测试来自土墩和基质的植物是否进化出遗传差异性状并适应当地（土壤生态型），或者性状差异是否来自表型可塑性。监测生长、存活和形态功能叶性状。不同起源和栖息地的植物之间的幼苗存活率没有差异。在两个起源的植物之间没有发现组成差异或没有遗传特征。然而，在原位实验中，不同栖息地的功能性状有所不同，白蚁丘的比叶面积 (SLA) 更高，叶干物质含量值更低，表明可塑性反应。与盆栽实验相比，原位塑性反应的幅度更大，这表明除土壤外，其他生态因素也驱动性状可塑性。我们得出结论，该物种的广泛生态位是由于其表达适应性表型可塑性的能力，而不是局部适应的基因型。与盆栽实验相比，原位塑性反应的幅度更大，这表明除土壤外，其他生态因素也驱动性状可塑性。我们得出结论，该物种的广泛生态位是由于其表达适应性表型可塑性的能力，而不是局部适应的基因型。与盆栽实验相比，原位塑性反应的幅度更大，这表明除土壤外，其他生态因素也驱动性状可塑性。我们得出结论，该物种的广泛生态位是由于其表达适应性表型可塑性的能力，而不是局部适应的基因型。