The Future Is Now: Toward a Predictive Theory of Microevolution

Marine microbes play important roles in biogeochemical cycles and ecosystem function. When predicting how marine systems might change as oceans acidify, we generally assume that we can scale up the short-term physiological responses of microbes to predict their long-term responses. However, because microbes have large populations, reproduce quickly, and have multiple methods for generating genetic variation (mutation, sex, horizontal gene transfer), they will certainly evolve on much shorter – possibly decadal – timescales. These short-term responses might translate to adaptive genetic change, or microevolution. This opens up the possibility of predicting future populations’ ability to withstand ocean acidification. I will discuss current experiments that use microbes to test how short-term responses might predict how much populations can adapt genetically to a changing environment, and how adaptation (an increase in fitness) translates into changes in phenotype. I will also touch on the challenges of applying studies done in established freshwater microbial model systems to marine microbial systems responding to ocean acidification, and outline some of the marine microbes that we are developing into model organisms for experimental evolution.