Niche differentiation along multiple functional‐trait dimensions contributes to high local diversity of Euphorbiaceae in a tropical tree assemblage

Abstract

1. Understanding the mechanisms that drive community assembly in species-rich tropical forest remains a fundamental challenge in ecology. Here, we integrated multivariate functional trait dimensions, phylogeny and metabolomics to test fundamental predictions concerning the role of differentiation with respect to abiotic and biotic niche axes in the maintenance of high local diversity of woody plants in the Euphorbiaceae.2. We measured 40 functional traits related to resource acquisition, photosynthetic capacity, hydraulic efficiency and secondary-metabolite profiles generated using untargeted metabolomics in all 26 Euphorbiaceae species in a 20-ha forest dynamics plot in tropical southwestern China. We examined the correlation structure of 40 traits using a trait networking approach. We coupled these traits with variation in soil nutrients, light environment, soil water content and herbivore pressure within the plot to assess niche differentiation in space. We compared phylogenetic signal among multivariate trait dimensions and secondary metabolites to assess niche differentiation in evolutionary time.3. Network analysis revealed that a small number of traits with high network centrality reflected variation in ecological strategy among the Euphorbiaceae. Using these high-centrality traits, we observed significant functional turnover along environmental gradients defined by light, soil moisture, soil nutrients and leaf herbivory, respectively. Most resource utilization traits showed significant phylogenetic signal, whereas almost all defensive traits lacked phylogenetic signal, including species similarity with respect to plant secondary metabolites.

Phytochemical diversity impacts herbivory in a tropical rainforest tree community

“…We classified herbivore damage into broad categories (e.g. hole feeding and margin feeding) according to Labandeira et al (2007) and further divided them into three diet‐breadth categories: generalised, intermediate, or specialised (Labandeira et al, 2007; Wang et al, 2022). Mean per cent herbivory and diet‐breadth values were calculated for each tree species.…”

The evolution of chemodiversity in plants—From verbal to quantitative models

“…However, patterns of chemical traits between species have been compared to null models for trait evolution on a phylogeny. For example, Volf et al (2018) and Wang et al (2023) used Brownian motion and white noise models. So far, however, these models cannot address intraspecific chemodiversity.…”

“…(2018) and Wang et al. (2023) used Brownian motion and white noise models. So far, however, these models cannot address intraspecific chemodiversity.…”

Functional genomics and co‐occurrence in a diverse tropical tree genus: The roles of drought‐ and defence‐related genes

“…Measurements of plant‐water relations and plant defence are possible, but traditional approaches can be challenging to broadly employ. This had led to important innovations that permit measures of traits like leaf osmotic potentials (Bartlett et al., 2012) or the metabolomic profiles of species on a community scale (Sedio et al., 2012; Wang et al., 2022, 2023). An alternative, but under‐utilized approach, has been functional genomics or transcriptomics (Swenson et al., 2017, 2023; Swenson & Jones, 2017).…”