TOEFL Reading: ETS-TOEFL阅读机经 - M05DQX8X2S38GI3ZL$

A variety of factors, including human activity, can affect the distribution of species. A. Research has shown that the biogeography of species can change even without human interference as can be seen In the wide distribution of willows along a wide range of river banks. B. Introducing a species to a new environment can have unintended consequences such as those that occurred when a butterfly was relocated to an environment that lacked its natural predator. C. The success of relocating two species together depends on how they help each other survive in a new environment as demonstrated by the South African bronze butterfly and geraniums. D. The study of the relocations of certain species to new habitats has been difficult because it is not always clear if the relocations were natural or caused by humans. E. Humans have relocated species for a variety of reasons, including obtaining new food sources, creating new industries, and taking advantage of the characteristics of certain species. F. Understanding the distribution of a species in its native habitat can be useful in controlling Its spread as a pest in Its new habitat.