Olivia Williams

Document Type

Honors Thesis


'Transgenerational plasticity' occurs when environmental cues alter the expression of traits in offspring and future generations. This experiment examined the influence of low-quality cyanobacteria (Anabaena) on across-generation responses in a common water flea (Daphnia pulicaria) to quantify whether changes in food quality from dietary cyanobacteria can induce transgenerational effects. Three Daphnia clones from Lake Mendota (WI) were maintained at 14C, 16:10 photoperiod until the third laboratory generation; animals from each clonal line were then reared for multiple generations on diets that contained varying amounts of cyanobacteria (either 100% Scenedesmus or 70% Scenedesmus, 30% Anabaena). General linear models and a posthoc Tukey test (SPSS v. 25) were used to analyze life history data. Daphnia fed cyanobacteria developed more slowly, were smaller in size, and produced fewer offspring. However, such differences in life history traits largely disappeared following the removal of cyanobacteria in the subsequent generation. Thus, exposure to low-quality cyanobacterial food did not induce strong transgenerational responses in Daphnia. These results are surprising because of the overwhelmingly negative response Daphnia have to cyanobacteria in the wild. Possible reasoning for the results encountered in this experiment is that the source lake for the animals used in this experiment is highly eutrophic, which may mean that the ancestors of these clones were already exposed to cyanobacteria. While these results raise questions about how influential food quality is on transgenerational responses, further research is still needed to determine whether the effects of cyanobacteria observed in the first and second generation are due to significant phenotypic influence from consuming cyanobacteria—as well as whether such effects may span generations in Daphnia clonal lines not previously exposed to cyanobacteria.

Publication Date






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