文档介绍：Overexploitati on
A species that faces overexploitation is one that may become severely endangered or even extinct due to the rate in which the species is being used. Unrestricted whaling during the 20th century is an example of overexploitation, and the whaling industry brought many species of whales to extremely low population sizes. When several whale species were nearly extinct, a number of nations (including the United States) agreed to abide by an international moratorium on whaling. Due to this moratorium, some whale species, such as the grey whale, have made remarkable comebacks, while others remain threatened or endangered.
Due to the trade in animal parts, many species continue to suffer high rates of exploitation. Even today, there are demandsfor items such as rhino horns and tiger bones in several areas of Asia. It is here that there exists a strong market for traditional medicines made from these animal parts.
More Factors
Disease, pollution, and limited distribution are more factors that threaten various plant and animal species. If a species does not have the natural genetic protection against particular pathogens, an introduced disease can have severe effects on that specie. For example, rabies and canine distemper viruses are presently destroying carnivore populations in East Africa. Domestic animals often transmit the diseases that affect wild populations,