Choices of sampling method bias functional components estimation and ability to discriminate assembly mechanisms

By Eric Lee
Jun 04th 2019

This issue’s cover image illustrates morphological differences, such as body size, between two ant species, a Polyrhachis individual and a few dozen individuals of a Pheidole species foraging on a baiting station; and where it can easily be envisioned how both species use their environment differently. Integrating species trait information into ecological analysis, the functional trait‐based approach has advanced our understanding and predictions of species distribution and community structure. However, different sampling methods may reveal asymmetrical trait patterns of identical community. If sampling‐related filtering on traits is overlooked, it may bias the estimation of functional components and the detection of underlying assembly processes. In the related article, Lee & Guénard compared functional trait information of ground‐dwelling ant communities sampled by pitfall traps and Winkler extractors, two commonly‐used sampling methods in terrestrial arthropods surveys, in two distinct habitats within a subtropical region (Hong Kong).

Their results show that sampling filters from different methods indeed affected the trait composition and diversity of ant communities asymmetrically. For example, trait composition of communities sampled by pitfall traps was dominated by larger sized, slender‐shaped and long‐legged ants as compared to Winkler extractors. Researchers should thus carefully plan their sampling design and discuss the results at the light of potential biases obtained through this artificial filtering process. This should limit misinterpretation of species assembly processes and strengthen predictions about species responses to their environment.


Photo credit: Roger H. Lee