PS 20-193 - Less, but more efficient: Warmer temperatures lead to lower acid phosphatase concentrations in carnivorous pitcher plants

Background/Question/Methods

Understanding how environmental conditions alter the function of organisms and communities is of great importance when considering future climate change. Sarracenia purpurea, Sarracenia flava, and their hybrid, Sarracenia x catesbaei, are carnivorous plants that co-exist in nutrient poor bogs, receiving most or all of their nutrients and minerals through their cup-shaped leaves (pitchers). These three pitcher plants utilize different carnivory strategies for prey digestion. S. purpurea mainly relies on a community of organisms within the pitcher to help break down prey; S. flava produces enzymes to release nutrients; and S. x catesbaei likely has a nutrient acquisition strategy that is intermediate between the two parental species. Based on these functional differences, we predict that S. purpurea will have lower production of digestive enzyme than S. flava and have the more thermally tolerant carnivory strategy. We also expect S. x catesbaei to show an intermediate response. In this study, we collected fluid from pitchers across ten sites varying in average June temperatures in North Carolina and Virginia. We then used colorimetric enzyme assays to measure acid phosphatase, chitinase, and protease activity. This study investigates 1) the differences in enzyme production across species and 2) the impacts of temperature on enzyme production.

Results/Conclusions

As predicted, we found that S. purpurea had lower enzyme concentrations than S. flava and that S. x catesbaei tended to show intermediate values. We also found that acid phosphatase (AP) concentration in the fluid was significantly affected by temperature. Additionally, increasing temperatures decreased AP concentration in S. flava more significantly than in S. purpurea. The decreased reliance of enzymatic digestion in S. purpurea may lead to a more resilient nutrient release response to temperature. AP concentration in S. x catesbaei was in between S. purpurea and S. flava. Because enzyme activity increases with temperature, our results suggest that pitcher plants in warmer areas require less AP than plants in colder areas. Overall, this study shows that site level differences in temperature may affect the nutrient release efficiency in these pitcher plants; however, the utilization of different carnivory strategies may lead to varying levels of response. Future studies will aim to couple the enzymatic findings of this study with the food web structure of the community living inside of the pitchers to better understand the mechanisms behind changing nutrient processing methods.