Meeting Abstract
Invasive predators can have devastating ecological and evolutionary impacts on native prey species within the ecosystems they invade. These effects may be pronounced when the predator is novel to the prey, a situation that is on-going in southcentral Alaska, where the large and voracious northern pike are invading the native range of the threespine stickleback. In this area, pike have caused the extirpation of several populations of stickleback, yet in some instances stickleback have persisted. Here, we report on phenotypic changes following introduction of pike into Scout Lake, Alaska, in which the stickleback persisted. In 2001 or 2002, pike were illegally introduced to Scout Lake. A fortuitous set of annual collections of stickleback from Scout Lake, beginning prior to the introduction of pike and continuing until the lake was poisoned by the Alaska Department of Fish and Game in 2009 to eliminate pike, makes it possible to evaluate the speed and temporal pattern of armor modification and shape change in stickleback. Preliminary data suggest that over this very short timeframe, stickleback evolved more robust armor (spines, lateral plates, and elements of the pelvic girdle), and possibly reduced body depth. The armor effects are directly related to predator deterrence, but the possible body shape changes suggest that stickleback were shifting from foraging on benthic habitats along the shoreline where pike hunt, to foraging on plankton in open water. A more fusiform body would be advantageous in such a situation. Here we evaluate changes in body shape and armor robustness over the pre-pike and post-pike periods to evaluate the extent, speed, and temporal pattern of contemporary evolution and the degree to which the two classes of traits evolve in concert.
