Species coexistence in a changing world

Abstract

The consequences of global change for the maintenance of species diversity will depend on the sum of each species responses to the environment and on the interactions among them. A wide ecological literature supports that these species-specific responses can arise from factors related to life strategies, evolutionary history and intraspecific variation, and also from environmental variation in space and time. In the light of recent advances from coexistence theory combined with mechanistic explanations of diversity maintenance, we discuss how global change drivers can influence species coexistence. We revise the importance of both competition and facilitation for understanding coexistence in different ecosystems, address the influence of phylogenetic relatedness, functional traits, phenotypic plasticity and intraspecific variability, and discuss lessons learnt from invasion ecology. While most previous studies have focused their efforts on disentangling the mechanisms that maintain the biological diversity in species-rich ecosystems such as tropical forests, grasslands and coral reefs, we argue that much can be learnt from pauci-specific communities where functional variability within each species, together with demographic and stochastic processes becomes key to understand species interactions and eventually community responses to global change.

Shedding light on shade: ecological perspectives of understorey plant life

“…Niche-based hypotheses to explain species coexistence have also been challenged by the neutral theory, which states that local coexistence is driven by broader biogeographical and evolutionary processes rather than by deterministic ecological mechanisms, emphasising the importance of intraspecific variability (Hubbell 2001;Valladares et al 2015). This theory is attractive for its simplicity, but provocative for its assumption that individuals of different species in rich communities are ecologically equivalent.…”

“…However, high within-species variability in leaf trait responses has been shown to be significantly affected by shading also in sub-boreal conifer species with different niche preferences (Lilles et al 2014). Both approaches, niche and neutrality, can be regarded as the opposing ends of a continuum from competitive to stochastic exclusion, with neutrality becoming more pronounced as species richness, niche overlap and dispersal capabilities increase (Gravel et al 2006;Valladares et al 2015), for example towards the Equator, where the prolonged vegetation period allows to successfully overcome tolerating several stress factors at the same time (Laanisto and Niinemets 2015).…”

Soil phosphorus heterogeneity promotes tree species diversity and phylogenetic clustering in a tropical seasonal rainforest

“…The tropical forests harbor an enormous diversity of plant species and are conservation priorities in a fast‐changing world (Figure S1); however, the mechanisms that determine tropical tree community assembly remain important yet not well‐solved questions in community ecology (Valladares, Bastias, Godoy, Granda, & Escudero, 2015). The classical niche theory predicts that communities with more environmental heterogeneity will have higher species diversity than those with less heterogeneity because more niches can be partitioned in a heterogeneous habitat (Figure 1a; Hutchinson, 1957; Kadmon & Allouche, 2007; Macarthur & Macarthur, 1961; Ricklefs, 1977; Svenning, 2001).…”

Trait-based plant ecology: moving towards a unifying species coexistence theory

“…In turn, trait-based ecology provides a mechanistic connection between ecological processes and these deterministic processes (Weiher and Keddy 1995;Westoby and Wright 2006;McGill et al 2006). From our perspective, the stochastic versus deterministic notions constitute complementary and not mutually exclusive aspects of a very complex process (Gravel et al 2006), and their relative importance varies across biomes and ecological conditions (Valladares et al 2015).…”