Consider that stickleback evolution has followed similar patterns in other lakes across the globe. Make a prediction about what would happen in an isolated lake with few predators if humans introduced predatory fish like trout. Support your prediction with evidence from the virtual lab.
The correct answer and explanation is:
In an isolated lake with few predators, the introduction of predatory fish like trout would likely cause significant changes in the stickleback population. In ecosystems where predators are absent, sticklebacks can evolve to exhibit traits that are suited to a predator-free environment, such as increased size, larger body armor, or more aggressive behavior to compete for food. However, once predatory fish like trout are introduced, these traits may no longer be advantageous, and natural selection would likely favor sticklebacks that are better equipped to avoid predation.
The evidence from the virtual lab shows that when predation pressure is present, sticklebacks tend to evolve traits that make them less susceptible to being eaten. These traits could include a reduction in body size, as smaller fish are harder to catch, or changes in behavior that make the fish more adept at hiding or avoiding predators. In lakes with few predators, sticklebacks might have evolved longer, more streamlined bodies, but with the introduction of trout, those longer bodies would make the fish more vulnerable.
Additionally, in isolated environments where resources are abundant, competition among sticklebacks may lead to more specialization and size variation. The sudden introduction of a predator would create an immediate ecological shift, forcing the fish to adapt to avoid being caught. Over generations, we might see a reduction in body size, more camouflage, or behavioral changes such as schooling to confuse the predator.
Thus, the introduction of trout into the isolated lake would lead to an increase in selection pressure on the stickleback population, favoring those individuals that can better avoid predation. The evolution of these traits would mirror what has been observed in other lakes, where the presence of predators drives a rapid and significant shift in stickleback characteristics.