Its called invasive species one example is the lion fish it rooms around the east cost of north America overpopulation harms the ecosystem
Dependent and independent variables are variables in mathematical modeling, statistical modeling and experimental sciences
Judging by the hair, you can find it's origin and as long as if you had a group of people to be looking at you can match the color and DNA of each person's hair to the hair you found when you were doing your forensics were at said crime scene. I don't necessarily know the processes that were taught but the <em>investigation</em> wouldn't be too difficult.