Microclimate structures communities, predation and herbivory in the High Arctic

Area of Science:

• Ecology
• Climate Change Biology
• Arctic Ecosystems

Background:

• Global warming is altering species and community structures through ecological interactions.
• Understanding local microclimatic effects is crucial for predicting macroclimatic change consequences.
• The High Arctic is rapidly changing, necessitating research into its ecological responses.

Purpose of the Study:

• To examine how parasitoid communities, herbivory, and parasitism rates vary with microclimate in the Arctic.
• To link community structure and interactions to species traits (parasitism strategy, phenology) and abiotic factors.
• To assess the impact of microclimate on interaction outcomes, specifically parasitism and herbivory rates.

Main Methods:

• Studied communities of avens (Dryas spp.), a specialist herbivore (Sympistis zetterstedtii), and its parasitoids along a mountain microclimatic gradient.
• Recorded parasitoid communities, herbivory rates on Dryas flowers, and parasitism rates in S. zetterstedtii larvae at 20 sites.
• Employed joint species distribution modeling to link community responses to microclimate and parasitoid traits.
• Utilized generalized linear and additive mixed models to analyze the effects of abiotic variables on interaction rates.

Main Results:

• Parasitism strategy and phenology were key drivers of local parasitoid community structure.
• Koinobiont parasitoids favored warmer, higher-elevation sites with earlier snowmelt and lower humidity.
• Earlier phenology species were more prevalent at cooler sites with later snowmelt.
• Microclimate significantly affected interaction outcomes: higher temperatures and lower humidity increased parasitism rates on S. zetterstedtii and herbivory rates on Dryas.
• Parasitism rates on the focal herbivore increased with higher temperature and lower humidity.

Conclusions:

• Microclimatic variation is a significant determinant of local community structure, species interactions, and interaction outcomes in Arctic ecosystems.
• Ongoing climate change is predicted to profoundly impact Arctic communities due to these microclimatic drivers.
• The study highlights the interconnectedness of species-level responses, community structure, and ecological interactions under changing climatic conditions.