五 、 閱 讀 測 驗 第 35 至 38 題為題組        Islands are different from a continent or mainland. The size and isolation of islands have a profoundeffect on island ecosystems and their inhabitants.         Scientists who specialize in species evolution have found that, among mammal species that settle onislands, big species tend to shrink while small ones are apt to enlarge. This phenomenon, discovered by J.Bristol Foster in 1964, has been called Foster’s rule, or the island effect. For instance, rodents (such as ratsand squirrels) living on islands tend toward gigantism, while big mammals (like deer and elephants) aremore likely to become dwarfed. Although there are a number of exceptions to this pattern, the trendgenerally holds true for both fossil species and living island mammals.          Foster’s rule shows that body size regulates everything. In a mainland environment, being large isoften a safer and adaptive form of avoiding predators. On an island, with few natural predators and lesscompetition, being really big is no longer an advantage； in fact, it can be a hindrance since a huge animalwill need a lot more food in order to survive and reproduce.         A new fossil study of island-dwelling proboscideans (i.e. prehistoric hairy elephants) further showsthat the physical attributes and ecological structure of an island may affect the degree of shrinking in bigmammals. On relatively balanced and species-rich islands, competition with other species often result in arelatively less dwarfed body size. In contrast, on smaller islands where food sources are limited andcompetitors lacking, members of this group become smaller surprisingly quickly. On one of the ChannelIslands 15 miles off the coast of France, the red deer dwarfed to one-sixth the size of deer on continentalEurope in a mere 6,000 years after the island became isolated.
【題組】35. What is the second paragraph mainly about?
(A) The reasons why mammals change and evolve through time.
(B) A comparison of gigantism and dwarfism on different islands.
(C) The different patterns of evolution for big and small island mammals.
(D) The similarity between the evolution of fossil species and that of living species.