McKinney 03 (Michael, Director of Environmental Studies, University of Texas, PHD from Yale, http://books.google.com/books?id=NJUanyPkh0AC&pg=PA274&lpg=PA274&dq=manatees+%22keystone+species%22&source=bl&ots=rB1vju6y6v&sig=isIAuB81-ZM_Hv4PAMp2EKt4lH8&hl=en&sa=X&ei=kaX7T_GoEYiorQHfrZ2LCQ&ved=0CGgQ6AEwCA#v=onepage&q=manatees%20%22keystone%20species%22&f=false, )
Are All Species Equally Important? With so many species at risk, triage decisions cannot be made on the basis of risk alone. Conservation biologists therefore often ask whether one species is more important than another. Ethically, perhaps one could argue that all species are equal; an insect may have as much right to live as a panther. But in other ways, in particular. In ecological and evolutionary importance, all species are not equal. Ecological importance reflects the role a species plays in its ecological community. Keystone species play large roles because they affect so many other species. Large predators, for example, often control the population dynamics of many herbivores. When the predators, such as wolves, are removed, the herbivore population may increase rapidly, overgrazing plants and causing massive ecological disruption. Similarly, certain plants are crucial food for many animal species in some ecosystems. Extinction of keystone species will often have cascading effects on many species, even causing secondary extinctions. Many therefore argue that saving keystone species should be a priority.