Determining the effect of temperature on species interactions in microcosms: a QPCR approach

Predicting the impact of environmental change is a major goal and challenge in ecology. With climate change threatening the biodiversity and ecosystem functioning of our natural ecosystems, understanding the effects of such change and how these are mediated through a community is of critical importance. Community stability could be severely affected by temperature through extinctions, alterations in species dominance and species-specific responses. One approach to testing the consequences of climate change on a community is to manipulate experimental aquatic microcosms. However, investigating community-level responses to change in experimental microcosms has been limited by the ability to accurately monitor the basal trophic level of bacteria. Here I develop a molecular approach to monitoring bacteria by using qPCR. The qPCR approach was successful for three bacterial species and produced sensitivity to the single cell. The qPCR approach was implemented in an experimental setting to aid the investigation of the relationships between temperature, species interactions and community properties. Direct temperature response was species-specific, but indirect interactions strongly mediated temperature through the community, altering competitor and predator response. Therefore, predicting species and community response to environmental change is dependent on knowledge of specific-species response, indirect pathways of interaction and the effects of community composition.