A Limited Competition

Limited resources and overpopulation can be a big problem. First of all, limited resources can mean many things. It can mean limited food, limited water, limited anything! In most cases, food is the problem. All species eat the same things as another species does. For example, birds and some mammals eat insects. If there were limited insects, and an overpopulation of birds and mammals who eat insects, what would happen?
       In this case, I think that evolution comes to view. While this competition goes on, some systems in each species' body might have an effect on this. For example, a dog. Has a dog always been like the species we've seen today? No, because it is proven that dogs were originated from wolves. We've all should've heard or known that a wolf has been domesticated as a pet a long time ago, so over generations and generations, the wolf has slowly changed into the dogs we see today. In fact, there's a huge variety of dogs now. 
       Would humans like today change as well? That's a question that no one can know. However, many things in life change. Whether it's an animal, or a resource, or a tree, or whatever. This doesn't mean that the changes are always good, but if we keep doing what we do best, then we will make a good chang