Delivering the promises of trait‐based approaches to the needs of demographic approaches, and vice versa

Abstract

Few facets of biology vary more than functional traits and life‐history traits. To explore this vast variation, functional ecologists and population ecologists have developed independent approaches that identify the mechanisms behind and consequences of trait variation.Collaborative research between researchers using trait‐based and demographic approaches remains scarce. We argue that this is a missed opportunity, as the strengths of both approaches could help boost the research agendas of functional ecology and population ecology.This special feature, which spans three journals of the British Ecological Society due to its interdisciplinary nature, showcases state‐of‐the‐art research applying trait‐based and demographic approaches to examine relationships between organismal function, life history strategies and population performance across multiple kingdoms. Examples include the exploration of how functional trait × environment interactions affect vital rates and thus explain population trends and species occurrence; the coordination of seed traits and dispersal ability with the pace of life in plants; the incorporation of functional traits in dynamic energy budget models; or the discovery of linkages between microbial functional traits and the fast–slow continuum.Despite their historical isolation, collaborative work between functional ecologists and population ecologists could unlock novel research pathways. We call for an integrative research agenda to evaluate which and when traits are functional, as well as their ability to describe and predict life history strategies and population dynamics. We highlight promising, complementary research avenues to overcome current limitations. These include a more explicit linkage of selection gradients in the context of functional trait–vital rate relationships, and the implementation of standardised protocols to track changes in traits and vital rates over time at the same location and individuals, thus allowing for the explicit incorporation of trade‐offs in analyses of covariation of functional traits and life‐history traits.

Functional traits explain the Hutchinsonian niches of plant species

“…Ecological theory has long postulated that traits such as rapid development and small body size should increase population growth in optimal environments (r max ; Pianka, 1970). Nowadays, the emerging research agendas of "functional population ecology" (Adler, Salguero-Gómez, Compagnoni, Hsu, & Ray-Mukherjee, 2014; Salguero-Gómez, Violle, Gimenez, & Childs, 2018) and "functional biogeography" (Violle et al, 2014;Yang, Cao, & Swenson, 2018) aim to link functional traits, fitness proxies and environmental gradients for multiple species. Studies generally address this challenging task by relating traits to niche estimates derived from species distribution models (SDMs) based on presence and abundance data (e.g., Chacón-Madrigal, Wanek, Hietz, & Dullinger, 2018;Costa et al, 2018).…”

“…In plant ecology, the task of linking traits, demographic performance and environmental variation is hampered by a lack of traitand demographic data across the geographical ranges of multiple species (McGill et al, 2006;Salguero-Gómez et al, 2018;Violle et al, 2014; but see Treurnicht et al, 2016). Most trait-based studies thus examined trait-performance relationships from single, life stage-specific proxies of performance, often measured at single or few localities.…”

Plant demographic and functional responses to management intensification: A long‐term study in a Mediterranean rangeland

“…The underlying assumption of the present study is that differential changes in species abundances in response to management intensification reflect differences in ecological success related to contrasting functional and life‐history strategies. Although this assertion can be considered as trivial, cross‐species comparative analyses of the link between populations’ demographic changes and plant functional traits, although one of the foundation stones of the discipline, remains scarce (Salguero‐Gómez, Violle, Gimenez, & Childs, ; Shipley et al., ). This is partly due to the fact that tracking demographic changes of natural plant populations for multiple coexisting species simultaneously is challenging, both practically and methodologically.…”

“…Linking traits and demography is a necessary step to advance the field, both theoretically and predictively (Enquist et al., ; Salguero‐Gómez et al., ). Here we show that a combination of traits widely used in plant functional ecology to describe phenotypes relates significantly to vital rates of populations, but we also argue that accounting for the local environmental context is essential to establish robust and predictable relationships between traits and demographic parameters.…”

Unifying functional trait approaches to understand the assemblage of ecological communities: synthesizing taxonomic divides

“…Are there opportunities to link traits to demographic rates(Salguero-Gómez et al 2018), behavioral syndromes, competition(Cadotte and Tucker 2017), trophic position(de Bello et al 2010, Fountain-Jones et al 2017 or other data to provide a more nuanced and three-dimensional view of how communities assemble in a given study area?• Do the responses of selected traits differ depending upon the study scale? Are considerations across scales important to answer a given research question?…”