Trait-based approaches to ecology have become especially popular in recent years. In particular, researchers are increasingly turning to biological traits to investigate questions pertinent to community dynamics, ecosystem services, and conservation. Despite attempts to provide clear and unambiguous definitions for 'trait' and 'functional trait', ambiguity persists in the interpretation and application of these terms among ecologists. Here we investigate the causes underlying this ambiguity, and test whether or not differences in term definitions and applications exist among different groups of ecologists.
We conducted a survey to investigate how ecologists define and operationalise the terms 'trait' and 'functional trait', and how their definitions and uses of these terms varied across biological sub-disciplines (e.g., ecosystem versus community ecology), geographic regions of research focus, and working taxa and biomes. Specifically, we tested whether or not researchers considered trait status to be conferred based upon the biological scale of relevance (e.g., individual versus population level), relation to environment, and heritability. We further asked researchers to consider a list of potential functional traits and choose which items among the list did not fit the definition. We received over 500 respondents from ecologists based in locations throughout the world.
Results/Conclusions
Respondents mostly agreed that biological traits can include measurements of behaviour, morphology, phenology, and physiology, but were divided on whether traits can include cultural or genetic metrics, and on the biological scale at which traits are measured. Potential functional traits on which ecologists were most divided included allele frequency, genotype, home range size, inbreeding coefficient, survival rate, and trophic group. For each of these examples, between 40-60% of survey participants rejected the use of the term 'functional trait'. For the remaining examples, rejection was either above 80% or below 20%. Nevertheless, we found that disagreements in the definition and application of the terms 'trait' and 'functional trait' did not vary considerably by researcher sub-discipline, geographic region, or working taxa or biome.
We conclude that ecologists vary in their definition of 'trait', but this is mostly with respect to the biological scale at which the term is applied. When presented with concrete examples, most ecologists agree on whether the term 'functional trait' is appropriate. Encouragingly, differences in the use of the terms 'trait' and 'functional trait' appear to be unrelated to the taxa, biomes, or geographic locations on which ecologists focus, or on the type of ecological research that they conduct.