Climate change is expected to significantly disrupt ecological communities. Climate change directly affects species by altering their habitat. However, indirect effects of climate change on species interactions, such as predation and competition, may have equally important impacts on species. These indirect effects may also amplify or counteract the direct effects of climate change on a species.
Researchers at the University of Alberta used modelling to test direct and indirect effects of climate change on an alpine butterfly (Parnassius smintheus), which lives in alpine meadows from New Mexico to the Yukon and only feeds on one plant genera (Sedum sp.). Lead author Dr. Alessandro Filazzola used data from citizen scientists to track both the butterfly and the plant across North America.
They found that models incorporating only direct effects of climate change on the butterfly showed an increase in its distribution. However, when Sedum sp. were included in the climate model, the butterfly’s distribution was significantly reduced. On the other hand, butterflies with generalist diets were less likely to be affected by climate change.
These indirect effects are more likely to affect butterflies because caterpillars often have specialized diets, feeding on one or a few plant species. These effects are also more pronounced in alpine environments, which are sensitive to temperature changes, as they are “closed systems” with limited areas for migration. A warming climate turns alpine meadow – butterfly habitat – into shrub or forest. Butterflies may not be able to reach the next mountaintop for resources and habitat. Snow is also important for alpine butterflies as it insulates their eggs in winter.
This study’s more holistic approach highlights the importance of considering the large and often neglected indirect effects of climate change on food webs of communities, which can lead to significant losses of biodiversity. Improving our ability to quantify the complex effects of climate change on ecosystems can help better mitigate biodiversity loss and maintain ecosystem services, such as pollination.
Read the paper here: Inclusion of trophic interactions increases the vulnerability of an alpine butterfly species to climate change in Global Change Biology
Sedum species, the larval food plant of P. smintheus