Microclimate and resource quality determine resource use in a range-expanding herbivore

Area of Science:

• Ecology
• Climate Change Biology
• Behavioral Ecology

Background:

• Climate change affects species' geographic ranges through direct and indirect environmental influences.
• Microclimates can modify specialist biotic interactions, impacting community dynamics and range shifts.
• The role of microclimatic variation in specialist biotic interactions remains under-explored.

Purpose of the Study:

• To investigate how microclimatic conditions influence the egg-laying behavior of a range-expanding herbivore.
• To quantify the impact of microclimate, resource availability, and individual fecundity on egg-laying rates.
• To assess the implications of these factors for climate-driven range expansion.

Main Methods:

• An in-field experiment was conducted to observe egg-laying behavior across natural microclimatic gradients.
• The study focused on the brown argus butterfly (Aricia agestis) as an exemplar species.
• Egg-laying rates were measured in relation to microclimate, host plant condition, and individual butterfly fecundity.

Main Results:

• Egg-laying rates varied by nearly two orders of magnitude due to microclimate, resource condition, and fecundity.
• Within-site variation in fecundity exceeded population-level differences attributed to average ambient temperatures.
• Higher temperatures did not impair female selection for high-quality host plants.

Conclusions:

• Microclimatic variation significantly influences specialist biotic interactions and can accelerate climate-driven range expansion.
• The thermal sensitivity of egg-laying behavior can enhance encounters with novel hosts in suitable microclimates.
• Understanding microclimate's role in biotic interactions is essential for predicting species' responses to climate change and maintaining ecological community resilience.