I have only messed around a little bit in franchise so don't have much insight yet. Research seems to be split in two sections - Vets research the animals in the research centre, mechanics research themed scenery, new facilities etc. in the workshop. I kind of discovered by accident that if you click on your research centre you can decide what animal to research but to do that you have to tell a staff member to do it. On the left hand side there is a list of the vets in your zoo and you need to drag them on to the animal research you want them to do. Mechanics ditto for the workshop. You can also access both screens in the research tab on the zoo menu.