Sometimes, the hardest part about doing library research is coming up with the right terms to use in search engines. You can start with your class reading. Another good place is to check the library's catalog for encyclopedias, dictionaries, and handbooks related to your topic (e.g., "evolution encyclopedia"). You will probably find a narrower topic of interest and the article will help you to decide which keywords to use.
Another way to find keywords to use is to do a search in one of the library's research databases. For example, I did a search for "behavior evolution" in ProQuest and found the article "Animal Behaviour: Evolution and Mechanisms". Going to the web page for the article, I see the subjects listed are Veterinary Science, Psychology, Biology-Zoology, and Anthropology. Often, the article itself will include keywords. You can use the subjects and keywords to build your search.
If you are looking for information on a specific animal or plant, you need to be careful. Say you are looking for how parasites change behavior in animals. That topic is too broad. What kind of parasites and what types of animals? Are you interested in cats in general (felids, felines, or family Felidae)? Or are you interested in the domestic cat (Felis catus)? Always use the scientific name in your search because a mountain lion can be called cougar, panther, puma, painter, and catamount, among others. But, no matter what common name is used, it will always be referred to as Puma concolor (formerly Felis concolor) in the scientific literature.