Phylogenetic conservatism in the relationship between functional and demographic characteristics in Amazon tree taxa

Leaf and wood functional traits of trees are related to growth, reproduction, and survival, but the degree of phylogenetic conservatism in these relationships is largely unknown. In this study, we describe the variability of strategies involving leaf, wood and demographic characteristics for tree genera distributed across the Amazon Region, and quantify phylogenetic signal for the characteristics and their relationships.

Leaf and wood traits are aligned with demographic variables along two main axes of variation. The first axis represents the coordination of leaf traits describing resource uptake and use, wood density, seed mass and survival. The second axis represents the coordination between size and growth. Both axes show strong phylogenetic signal, suggesting a constrained evolution influenced by ancestral values, yet the second axis also has an additional, substantial portion of its variation that is driven by functional correlations unrelated to phylogeny, suggesting simultaneously higher evolutionary lability and coordination.

Synthesis. Our results suggest that life-history strategies of tropical trees are generally phylogenetically conserved, but that tree lineages may have some capability of responding to environmental changes by modulating their growth and size. Overall, we provide the largest-scale synopsis of functional characteristics of Amazonian trees, showing substantial nuance in the evolutionary patterns of individual characteristics and their relationships.

Methods
Genus-level data on Amazon trees functional traits and demographic characteristics (see methods in the manuscript).

树木叶片与木材功能性状与其生长、繁殖及存活紧密相关，但这类关联的系统发育保守性（phylogenetic conservatism）程度迄今仍未明确。本研究针对分布于亚马孙区域的树木属级类群，刻画了涵盖叶片、木材及种群统计特征的策略变异情况，并量化了各性状及其关联的系统发育信号（phylogenetic signal）。

叶片与木材功能性状沿两条主要变异轴与种群统计变量形成协同关联。第一条轴代表描述资源获取与利用的叶片性状、木材密度、种子质量及存活能力的协同关系；第二条轴则代表个体大小与生长速率间的协同关系。两条轴均表现出强烈的系统发育信号，表明其演化受祖先性状值约束；但第二条轴的变异另有相当一部分由与系统发育无关的功能关联驱动，这意味着该轴同时具备更高的演化易变性（evolutionary lability）与功能协同性。

综合分析：本研究结果表明，热带树木的生活史策略整体上具有系统发育保守性，但树木支系仍可通过调控自身生长与个体大小来响应环境变化。总体而言，本研究提供了目前最大尺度的亚马孙树木功能性状综述，揭示了单个性状及其关联的演化模式存在显著的精细差异。

研究方法
本数据集包含亚马孙树木属级功能性状与种群统计特征数据（详细方法参见论文正文）。