Resource limitation determines realized thermal performance of consumers
in trophodynamic models.
Abstract
1. Thermal performance curves (TPCs) are commonly used to forecast
species’ responses to temperature change. Recent work has demonstrated
that the breadth and shape of a consumer’s TPC change with resource
densities, highlighting the potential for inaccurate forecasts if
resource densities are not static. In particular, if resource densities
decline, the optimal temperature and breadth of thermal performance also
declines leading to an enhanced risk of warming, particularly among
species that may incur additional costs of behavioral thermoregulation.
2. Here, we investigate the relationship between resource density and
temperature (warming) on the persistence of a consumer population which
exerts top-down control on its resource via trophic interaction. Trophic
coupling generally reduces the potential for resource declines to
exacerbate the negative effects of warming on consumers; when warming
has negative effects on the consumer, resource densities tend to
increase due to a reduction in top-down control. However, if resources
are more sensitive to warming (e.g. due to an asymmetry amongst their
thermal performance curves), the negative effects of warming on
consumers can be exacerbated by declining resources. 3. Our work
elucidates the importance of jointly considering temperature and
resource limitation when utilizing assessing the thermal performance of
species. We demonstrate how knowledge of the thermal performance of a
resource population can be used to generate realized consumer thermal
performance curves.