How do I replace an alias by the original file it is linking to?

I have a folder containing several alias for pdf's that each have > 200 mb. Each pdf is in a different location on my drive. I need to compress all of those files. What is the fastest way to do it? There is always the slow way of going to each of the alias, right clicking it, copying the original to a predefined folder, repeat this procedure for every alias and finally compress the folder with all the original pdfs Evidently this will take forever! Is there a fastest way? For example using Terminal. Related, Is it possible to copy the original file of an alias using keyboard shortcuts?