E&E Fall 2021 Seminar Series:
Dr. Lacey Rzodkiewicz
University of Pittsburgh - Turcotte Lab
"Toxigenicity in an aquatic system: Untangling the web of direct and indirect interactions"
Wednesday, September 29th, 2021
A219B Langley Hall
12:00 PM
Abstract:
Allelochemicals, toxins that suppress competitors, may not only change ecological outcomes but act as a selective force. Therefore, allelopathic toxins could contribute to eco-evo feedbacks wherein changes to ecological outcomes can drive evolutionary response to again alter ecological outcomes. Harmful algal blooms provide a system for testing eco-evo dynamics of toxins. Harmful algal blooms consist of both toxic and nontoxic genotypes of cyanobacteria. Toxic cyanobacteria may produce cyanotoxins that reduce the success of aquatic plant competitors and deter predators (direct effects model). If heritable variation in cyanotoxin sensitivity exists in aquatic plants or predators, communities may adapt in response to cyanotoxin presence. I will discuss preliminary data from a cyanotoxin sensitivity test of thirty genotypes of two duckweed species (Lemna minor and Spirodela polyrhiza). Preliminary data indicate genetic variation exists in relevant biomarkers including growth and proxies for photosynthetic capacity, indicating direct ecological effects as well as the possibility for the cyanotoxin to act as a selective force. However, it is possible that cyanotoxins may indirectly influence additional community members such as herbivores of aquatic plant competitors (indirect effects model). For example, indirect effects of toxin presence could result in changes to herbivore success. To address the question of indirect effects, I will introduce a field mesocosm study wherein a five player community was manipulated to assess the impact of toxin presence on top-down (herbivore-driven) control of duckweeds. Preliminary data indicate the possibility of interactions among toxin presence and herbivore success.