How does the ecosystem get affected by an animal going extinct?

Badly. Its prey would overpopulate, depleting their own resources, until they would actually threaten the existence of their own species as well as any other animals that might feed on similar things. as a result the animals could either turn to feeding on man-made crops or slowly destroy an entire habitat destroying its vegetation. if this were to happen in lower world countries locals could even go hungry due to a general lack in resources.