No pervasive relationship between species size and local abundance trends

Despite expectations that global anthropogenic pressures on species with communities may be size biased, this relationship has not been tested on a large scale. Here the authors use existing databases to show that larger species have not experienced more declines in abundance within their respective communities than small species. Although there is some evidence that larger species could be more prone to population declines, the potential role of size traits in determining changes in community composition has been underexplored in global-scale analyses. Here, we combine a large cross-taxon assemblage time series database (BioTIME) with multiple trait databases to show that there is no clear correlation within communities between size traits and changes in abundance over time, suggesting that there is no consistent tendency for larger species to be doing proportionally better or worse than smaller species at local scales.

Automated summary

Despite expectations, the relationship between global anthropogenic pressures and size bias in species with communities has not been widely tested. The study shows that larger species have not experienced more declines in abundance within their communities than small species, suggesting that there is no consistent tendency for larger species to be doing proportionally better or worse than smaller species at local scales. Further exploration is needed to understand the potential role of size traits in determining changes in community composition on a global scale.