Extinction of living things can have a great negative impact on our ecosystem. The ecosystem is defined as "an area that contains organisms (e.g., plants, animals, bacteria) interacting with one another and their non-living environment. Ecosystems can be of any size (e.g., forest, meadow, and log)". When a component of the ecosystem becomes extinct, the effects can disrupt nature and be devastating.
The specific impact the extinction of the Dodo bird had on the ecosystem primarily has to do with specific trees. As discussed in Thinkquest, "It was not a coincident that the trees stopped germinating 300 years ago and the Dodo became extinct 300 years ago. In fact, the dodo ate the fruit of this tree, and it was only by passing through the Dodo's digestive system that the seeds became active and could grow." So without the Dodo bird present, the tree it fed on also became extinct. Without the tree, the natural habitat was changed, thus limiting food and shelter for other animals, which in turn may have forced them to leave or be vulnerable to predators. Also, any animals that preyed upon the Dodo bird also would have lost their food source with the extinction.
Animals that preyed on the dodo bird had less possibility for food, and if an animal only preyed on a dodo bird (which is unlikely) it would have also gone extinct. The dodo could have also had many useful traits for its environment such as helping spread seeds or fertilizing some plants, and without the dodo this relationship would have also been ruined and could have caused the extinction of several plants/tree, which would have lessen the amount of shelters for animals.