The animal whose absence would have the greatest negative effect on the ecosystem is the wolf.
Wolves are apex predators in this scenario and play a crucial role in regulating the populations of other species, such as deer, foxes, and rabbits. Without wolves, the populations of deer and rabbits could increase significantly, potentially leading to overgrazing and depletion of vegetation, which would disrupt the entire ecosystem. Additionally, the absence of wolves would remove the predation pressure on foxes, potentially leading to an imbalance in their populations as well.
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