Functional traits and phenotypic plasticity modulate species coexistence across contrasting climatic conditions

Abstract

Functional traits are expected to modulate plant competitive dynamics. However, how traits and their plasticity in response to contrasting environments connect with the mechanisms determining species coexistence remains poorly understood. Here, we couple field experiments under two contrasting climatic conditions to a plant population model describing competitive dynamics between 10 annual plant species in order to evaluate how 19 functional traits, covering physiological, morphological and reproductive characteristics, are associated with species’ niche and fitness differences. We find a rich diversity of univariate and multidimensional associations, which highlight the primary role of traits related to water- and light-use-efficiency for modulating the determinants of competitive outcomes. Importantly, such traits and their plasticity promote species coexistence across climatic conditions by enhancing stabilizing niche differences and by generating competitive trade-offs between species. Our study represents a significant advance showing how leading dimensions of plant function connect to the mechanisms determining the maintenance of biodiversity.

Dos and don'ts when inferring assembly rules from diversity patterns

“…Second, ignoring small‐scale factors, such as intraspecific variation in trait values (Albert et al, 2012; Siefert et al, 2015) and the fine‐scale spatial arrangement of individuals (Diekmann, Law & Metz, 2000), can lead to the underlying processes being overlooked because their effects may not scale up to large‐scale diversity patterns (Araujo & Rozenfeld, 2014; Thuiller et al, 2010; Turcotte & Levine, 2016). For example, it has been shown that trait plasticity increases niche differences in communities and thereby stabilizes coexistence and promotes diversity (Pérez‐Ramos, Matías, Gómez‐Aparicio, & Godoy, 2019). This biotic filtering mechanism would remain unnoticed when relying solely on the mean traits of species.…”

Vacant yet invasible niches in forest community assembly

“…The simulations were performed under stationary climate, without long-term trends, but with seasonal and inter-annual variation. This allows (a) to focus on the internal community dynamics and assembly processes, rather than the influence of environmental change; and (b) to respect the assumption of consistent mapping between trait and niche space which might not hold under varying environment (Adler et al, 2012;Angert et al, 2009;Pérez-Ramos et al, 2019). Each site is defined by baseline (climate and soil) conditions, and inter-annual variability (i.e.…”

“…Moreover, the trait-based view of community ecology (McGill et al, 2006) provides a link with the niche, and a way to understand and predict how biotic and abiotic processes determine community assembly (Weiher et al, 2011). While the link between species niches and functional traits is a central assumption of trait-based community ecology, it is not strongly supported by empirical evidence because it can be modulated by environmental conditions (Adler et al, 2012;Angert, Huxman, Chesson, & Venable, 2009;Pérez-Ramos, Matías, Gómez-Aparicio, & Godoy, 2019). If we assume a consistent mapping between traits and niche axes under stable environmental conditions, recasting community assembly using trait (i.e.…”

Natural enemies have inconsistent impacts on the coexistence of competing species

“…The larval competition of Drosophila often occurs within individual fruits that represent a discrete and temporary resource suitable for only a single generation of flies (Atkinson & Shorrocks 1981;Shorrocks 1991). In this way, the population dynamics of Drosophila resemble those for annual plants that have been the focus of the majority of recent coexistence work (Levine & HilleRisLambers 2009;Pérez-Ramos et al 2019). Our starting point is a Beverton-Holt model without any carry-over between generations:…”