The ecological causes of functional distinctiveness in communities

Abstract

Recent work has shown that evaluating functional trait distinctiveness, the average trait distance of a species to other species in a community offers promising insights into biodiversity dynamics and ecosystem functioning. However, the ecological mechanisms underlying the emergence and persistence of functionally distinct species are poorly understood. Here, we address the issue by considering a heterogeneous fitness landscape whereby functional dimensions encompass peaks representing trait combinations yielding positive population growth rates in a community. We identify four ecological cases contributing to the emergence and persistence of functionally distinct species. First, environmental heterogeneity or alternative phenotypic designs can drive positive population growth of functionally distinct species. Second, sink populations with negative population growth can deviate from local fitness peaks and be functionally distinct. Third, species found at the margin of the fitness landscape can persist but be functionally distinct. Fourth, biotic interactions (positive or negative) can dynamically alter the fitness landscape. We offer examples of these four cases and guidelines to distinguish between them. In addition to these deterministic processes, we explore how stochastic dispersal limitation can yield functional distinctiveness. Our framework offers a novel perspective on the relationship between fitness landscape heterogeneity and the functional composition of ecological assemblages.

Trait–environment relationships depend on species life history

“…Definitions of ecological strategies usually assume that one combination of traits corresponds to one environment (a "one-to-one mapping" from environment to strategy) (Marks & Lechowicz, 2006; Dias et al, 2020). As a consequence, the possibility that local divergence in trait values results from multiple phenotypic optima is still overlooked in functional ecology (Dias et al, 2020;Munoz et al, 2023). One reason is that a complex environment (here, both stress and disturbance at intermediate levels) can be either considered as a single environment, possibly filtering multiple strategies (van der Maarel & Sykes, 1993;Frenette-Dussault et al, 2012), or as multiple micro-environments, each filtering one particular strategy (Barbaro et al, 2004).…”

Changes in species richness with climate change in subalpine communities are dependent on regional environmental conditions and local functional composition

“…Plant community richness is known to be highly dependent on the functional composition of plant communities closely linked to biotic interactions, i.e., facilitation and competition (Grime, 1973;Michalet et al, 2006;Michalet et al, 2023;Munoz et al, 2023).…”

“…Plant community richness is known to be highly dependent on the functional composition of plant communities closely linked to biotic interactions, i.e., facilitation and competition (Grime, 1973; Michalet et al., 2006; Michalet et al., 2023; Munoz et al., 2023). Because functional composition also varies with environmental conditions, in particular climate and soil types (Díaz et al., 2016; Joswig et al., 2022), the effect of global change on diversity is likely to be mediated by changes in functional composition (Bjorkman et al., 2018; Niittynen et al., 2020; Bektas et al., 2023).…”

Beyond trait distances: Functional distinctiveness captures the outcome of plant competition

“…In this study, we argue that functional trait distinctiveness, an emerging facet of trait diversity (Munoz et al, 2023;Violle et al, 2017), can help capture the outcomes of PPI on the performance of both individual plants and groups of coexisting plants. Trait distinctiveness corresponds to the average trait distance between a given species (or genotype) and all the components of a given species pool (Grenié et al, 2018).…”