In conservation biology, invader potential is the qualitative and quantitative measure of a given invasive species probability to invade a given ecosystem. Exotic species with high invader potential are ones with high tolerance of different climates, dissolved oxygen content (for aquatic organisms), high propagule pressure and species with a large number of individuals introduced. The last factor is called a transport vector, for instance, sea lampreys and zebra mussels were transported into the Great Lakes through the vector of ballast water in ships. Transport vector is one of the most important factors, because if a large enough number of individuals are transported to an area that they cannot thrive in, a mutation within that population to thrive in the new ecosystem is more likely.