Body size responses to the combined effects of climate and land use changes within an urban framework

Alterations in body size can have profound impacts on an organism's life history and ecology with long-lasting effects that span multiple biological scales. Animal body size is influenced by environmental drivers, including climate change and land use change, the two largest current threats to biodiversity. Climate warming has led to smaller body sizes of many species due to impacts on growth (i.e., Bergmann's rule and temperature-size rule). Conversely, urbanization, which serves as a model for investigating the effects of land use changes, has largely been demonstrated to cause size increases, but few studies have examined the combined influences of climate and land use changes on organism size. We present here the background theory on how each of these factors is expected to influence body size, summarize existing evidence of how size has recently been impacted by climate and land use changes, and make several recommendations to guide future research uniting these areas of focus. Given the rapid pace of climate change and urbanization, understanding the combined effects of climate and land use changes on body size is imperative for biodiversity preservation.