Sinerely thank you for your answers. I known some new knowledges from your answers. And the reason provided the question by me is that whether we could better prevent new harmful virus or product broad-spectrum vaccine from the perspective that to thoroughly understand why virus exsit. I don't know if the idea is correct. Because I am very intereted in microorganism /virus study, even though I am a master in animal behavior. And I am trying my best to obtain a PhD offer in microogram research field.

Greetings; Viruses are all parasites. Parasites exist in every ecosystem as far as I know. So the question could be generalized to consider the ecological role of parasites as consumers. Ecologically they aren't any different from little, specialist predators. So Xinxin, we generally view viruses negatively because either we are the ones being consumed or the viruses are competing with us for access to some species that we also consume - domestic animals or crops for example.

With that description in mind, the evolution of viruses is no different than the evolution of any other biological interaction and there is a huge literature on that subject.

Here are a couple of citations that might give you some idea of the range of topics. Best regards, Jim Des Lauriers

Article Evolution in agriculture: The application of evolutionary ap...

Article Biotic Interactions and Macroevolution: Extensions and Misma...

Thank you very much. The sentence that " Ecologically they aren't any different from little, specialist predators" gived me a entirely new think for my initial question. And I will read carefully papers you recommended me. Again thank you sincerely James Des Lauriers