Tysklind Niklas, Etienne Marie-Pierre, Scotti-Saintagne Caroline, Tinaut Alexandra, Casalis Maxime, Troispoux Valerie, Cazal Saint-Omer, Brousseau Louise, Ferry Bruno, Scotti Ivan
INRAE UMR0745 EcoFoG AgroParisTech Cirad CNRS Université des Antilles Université de Guyane Kourou Cedex France.
CNRS IRMAR - UMR 6625 Univ Rennes Rennes France.
Ecol Evol. 2020 Sep 17;10(19):10735-10753. doi: 10.1002/ece3.6731. eCollection 2020 Oct.
Trees are characterized by the large number of seeds they produce. Although most of those seeds will never germinate, plenty will. Of those which germinate, many die young, and eventually, only a minute fraction will grow to adult stage and reproduce. Is this just a random process? Do variations in germination and survival at very young stages rely on variations in adaptations to microgeographic heterogeneity? and do these processes matter at all in determining tree species distribution and abundance? We have studied these questions with the Neotropical tree species. In the Guiana shield, are represented by at least two sympatric taxa or ecotypes, found almost exclusively in bottomlands, and a yet undescribed more generalist taxon/ecotype, . A reciprocal transplantation experiment (510 seeds, 16 conditions) was set up and followed over the course of 6 years to evaluate the survival and performance of individuals from different ecotypes and provenances. Germination, survival, growth, and herbivory showed signs of local adaptation, with some combinations of ecotypes and provenances growing faster and surviving better in their own habitat or provenance region. was strongly penalized when planted outside its home habitat but showed the fastest growth rates when planted in its home habitat, suggesting it is a specialist of a high-risk high-gain strategy. Conversely, behaved as a generalist, performing well in a variety of environments. The differential performance of seeds and seedlings in the different habitats matches the known distribution of both ecotypes, indicating that environmental filtering at the very early stages can be a key determinant of tree species distributions, even at the microgeographic level and among very closely related taxa. Furthermore, such differential performance also contributes to explain, in part, the maintenance of the different ecotypes living in intimate sympatry despite occasional gene flow.
树木的特点是产生大量种子。虽然这些种子中的大多数永远不会发芽，但仍有大量种子会发芽。在那些发芽的种子中，许多会在幼年时死亡，最终，只有极小一部分会成长到成年阶段并繁殖。这只是一个随机过程吗？幼年阶段发芽和存活的差异是否依赖于对微观地理异质性的适应差异？这些过程在决定树种分布和丰度方面到底重要吗？我们用新热带树种研究了这些问题。在圭亚那地盾， 由至少两个同域分类群或生态型代表，几乎只在低地发现，还有一个尚未描述的更具通用性的分类群/生态型， 。我们设置了一个相互移植实验（510颗种子，16种条件），并在6年时间里跟踪，以评估不同生态型和种源个体的存活和表现。发芽、存活、生长和食草情况显示出局部适应的迹象，一些生态型和种源的组合在其自身栖息地或种源区域生长得更快且存活得更好。 在其原生栖息地之外种植时受到严重惩罚，但在其原生栖息地种植时显示出最快的生长速度，这表明它是一种高风险高收益策略的特化物种。相反， 表现得像一个通才，在各种环境中都表现良好。种子和幼苗在不同栖息地的差异表现与两种生态型的已知分布相匹配，这表明即使在微观地理层面以及亲缘关系非常密切的分类群之间，早期阶段的环境筛选也可能是树种分布的关键决定因素。此外，这种差异表现也部分有助于解释，尽管偶尔有基因流动，但生活在紧密同域的不同生态型是如何维持的。
