Development of a new apparatus to partition ant body size reveals their respective functional role within ant communities

The rapid decline of biodiversity is directly threatening the maintenance of important ecosystem processes. Yet, biodiversity loss is not homogeneous, with species presenting specific traits being more prone to extinction. Ultimately this can lead to potential disruption of key ecosystem functions. Ants are ubiquitous and abundant in all terrestrial ecosystems. They provide a plethora of ecosystem functions and thus are well suited for studies assessing ecological processes. Within ant communities, body size of different species can vary by several orders of magnitude reflecting different ecologies. To this point, however, our understanding of the efficiency of ecological processes by different classes in function of their body size remains largely unexplored under field conditions. This is in part due to a lack of adequate methodology for an easy and accurate assessment of their respective contributions. Here, we describe a novel approach that separates ants into three size classes based on two parameters: height of the access point and size of the entrance; and evaluated the success of this method by assessing morphometric parameters of the size classes post-filtering and quantifying the scavenging efficiency as a key ecological process. This method successfully segregated individuals based on their body size, with the large-size treatment allowing access to ants 3 times larger than ants on the medium-size treatment and 5 times larger than those on the small-size treatment. The large-size treatment was the most efficient, removing 7 times more bait per hour than the medium-size treatment and 40 times more than the small-size treatment. This approach provides a new, adjustable method for differential exclusion in the field, highlighting the role that different size classes play within a community. This opens new opportunities to study the relative role of specific functional traits, and the importance of ecological interactions in shaping ecosystem functions.