Contrasting short- and long-term outcomes of pairwise interactions between caddisflies at a hydrologically heterogeneous range margin

Project Author
Issue Date
Shepard, Isaac D.
Wissinger, Scott A.
Greig, Hamish S.
Thumbnail Image
First Reader
Additional Readers
Competition , Range-shifts , Species interactions , Temporal dynamics , Trichoptera
1. Climate change is leading many species to shift their geographical ranges. Species undergoing these range shifts often are moving into areas with heterogeneous abiotic conditions. Additionally, these range-shifting species will encounter resident species with whom they will compete for space and/or resources. However, the ways that these abiotic and biotic factors interact to influence the establishment and persistence of range-shifting species has received little attention. 2. Here, we conduct an in situ cage experiment examining how a local wetland hydroperiod gradient (i.e., temporary and semi-permanent ponds) and competition with a resident caddisfly species, Asynarchus nigriculus, influences the survival of the range-shifting species Limnephilus picturatus. We then use long-term survey data of population densities of these two species to determine whether pairwise interactions observed in the cage experiment translated into long-term dynamics. 3. The cage experiment revealed that A. nigriculus had a strong, negative effect on the survival of the range-shifting species L. picturatus, regardless of hydroperiod. However, we observed no relationship between the densities or occurrence of L. picturatus and A. nigriculus in long-term data for either temporary or semi-permanent ponds. 4. Our results suggest that landscape-level abiotic heterogeneity at range margins may not always be important for mediating antagonistic interactions between resident and range-shifting species. However, although an interaction appears ecologically significant in short-term field studies, broader context is needed to understand whether those types of interactions mediate species' distributions and abundance through time. 5. At face-value, our results from the field experiment and long-term data analysis did not align. This suggests that other factors such as additional competitive or trophic interactions may be more important drivers behind the population dynamics of this range-shifting species at its new upper-elevational limit.
Environmental Science and Sustainability
Shepard, I. D., Wissinger, S. A., & Greig, H. S. (2023). Contrasting short- and long-term outcomes of pairwise interactions between caddisflies at a hydrologically heterogeneous range margin. Freshwater Biology, 68, 202–211.