BIO 227 Lecture Notes - Lecture 5: Florida Panther, Passenger Pigeon, American Bison
Document Summary
External factors that cause species to become endangered: evil quartet o habitat destruction o exotic species introduced/ disease o overexploitation o ecological linkages/ cascading effect. Intrinsic factors that cause species to become endangered: species that are a resource for humans or compete with humans for a shared resource o fisheries with by-catch o ex. Turtles an humans utilize the same beach habitat o changes of one system to another (ex. Prairie to agriculture: specialists o have a particular resource that they utilize and cannot survive without (not generalists) o ex. American bison, passenger pigeon) o small, highly localized populations are very vulnerable. Close to the brink of extinction- can"t withstand much impact. Genetic inbreeding and genetic drift can reduce individual"s fitness. Why are some species rarer than others: restriction to uncommon habitats, species restricted to vernal pools, limited to a small geographic range, occur at low population densities.
