Grasshopper response to reductions in habitat area as mediated by subfamily classification and life history traits

Although the loss of species is often attributed to reductions in habitat area, heterogeneity and connectivity, species specific traits and taxonomic relatedness can be important in explaining which species groups may be most impacted by the fragmentation process. In this study, using urban grassland fragments within the Front Range of northern Colorado, USA, we quantified the degree to which grasshopper species numbers declined with reductions in habitat area. We then examined the degree to which subfamily grouping (Gomphocerinae, Melanoplinae, Oedipodinae) and variation in life history characteristics (body size, dispersal ability, feeding preference and juvenile emergence time) explained which grasshopper species groups might be most impacted by reductions in habitat size. Our results showed a strong species-area relationship for grasshoppers across the urban fragments. Grasshoppers in different subfamily groupings were found to respond differentially, with the Melanoplinae being least affected by reductions in habitat area, while the other subfamilies responded similarly and lost species at a higher rate. Species with different feeding strategies were also found to respond differentially, with forbivorous species being least affected by the reductions in habitat area, while the graminivorous and herbivorous (mixed-feeders) responded similarly and lost species at a higher rate. As Melanoplinae tend to be forb feeders, this may partially explain why the subfamily was not as affected by the fragmentation process as the Gomphocerinae and Oedipodinae (who tend to be grass and mixed-feeders, respectively). Species that differed in body size and dispersal ability did not display differential responses to reductions in habitat area.