Appendix S1 from Rapid evolution mitigates the ecological consequences of an invasive species (<i>Bythotrephes longimanus</i>) in lakes in Wisconsin

2017-06-21T13:47:53Z (GMT) by Michael K. Gillis Matthew R. Walsh
Invasive species have extensive negative consequences for biodiversity and ecosystem health. Novel species also drive contemporary evolution in many native populations, which could mitigate or amplify their impacts on ecosystems. The predatory zooplankton, <i>Bythotrephes longimanus</i>, invaded lakes in Wisconsin, USA, in 2009. This invasion caused precipitous declines in zooplankton prey (<i>Daphnia pulicaria</i>), with cascading impacts on ecosystem services (water clarity). Here, we tested the link between <i>Bythotrephes</i> invasion, evolution in <i>Daphnia</i> and post-invasion ecological dynamics using 15 years of long-term data in conjunction with comparative experiments. Invasion by <i>Bythotrephes</i> is associated with rapid increases in the body size of <i>Daphnia</i>. Laboratory experiments revealed that such shifts have a genetic component; third-generation laboratory-reared <i>Daphnia</i> from ‘invaded’ lakes are significantly larger and exhibit greater reproductive effort than individuals from ‘uninvaded’ lakes. This trajectory of evolution should accelerate <i>Daphnia</i> population growth and enhance population persistence. We tested this prediction by comparing analyses of long-term data with laboratory-based simulations, and show that rapid evolution in <i>Daphnia</i> is associated with increased population growth in invaded lakes.