【文章內(nèi)容簡介】 ed to islands by other organisms, such as sea birds that travel long distances with seeds clinging to their feathers. 5 supports the idea that the Galapagos island chain was able to bee “one of the world39。s greatest showcases of evolution” primarily because ofA. the richness of the volcanic soil of each of the islands in the chainB. the distance of the individual islands from each other and from the mainlandC. the relativity long time it took for the islands to bee covered by organismsD. the outdoor laboratories that scientists have built on the islands to study evolutionparagraph 6The species on the Galapagos Islands today, most of which occur nowhere else, descended from organisms that floated, flew, or were blown over the sea from the South American mainland For instance, the Galapagos island chain has a total of thirteen species of closely related birds called Galapagos finches These birds have many similarities but differ in their feeding habits and their beak type, which is correlated with what they eat Accumulated evidence indicates that all thirteen finch species evolved from a single small population of ancestral birds that colonized one of the islands. Completely isolated on the island after migrating from the mainland, the founder population may have undergone significant changes in its gene pool and bee a new species. Later, a few individuals of this new species may have been blown by storms to a neighboring island. Isolated on this second island, the second founder population could have evolved into a second new species, which could later recolonize the island from which its founding population emigrated. Today each Galapagos island has multiple species of finches, with as many as ten on some islands. to paragraph 6. what is true about the thirteen species of Galapagos finches?A. All thirteen species are now found on most of the Galapagos IslandsB. All thirteen species are descended from the same population of ancestral birdsC. All thirteen species evolved on the island that was originally colonized by finches from the mainland.D. All thirteen species occur only in small, pletely isolated populations. at the four squares [■] that indicate where the following sentence could be added to the passage.This process of speciation and colonization could have been repeated over and over again, gradually involving all the islands in the chain.The species on the Galapagos Islands today, most of which occur nowhere else, descended from organisms that floated, flew, or were blown over the sea from the South American mainland For instance, the Galapagos island chain has a total of thirteen species of closely related birds called Galapagos finches These birds have many similarities but differ in their feeding habits and their beak type, which is correlated with what they eat Accumulated evidence indicates that all thirteen finch species evolved from a single small population of ancestral birds that colonized one of the isolated on the island after migrating from the mainland, the founder population may have undergone significant changes in its gene pool and bee a new species. [■] Later, a few individuals of this new species may have been blown by storms to a neighboring island. [■]Isolated on this second island, the second founder population could have evolved into a second new species, which could later recolonize the island from which its founding population emigrated.[■]Today each Galapagos island has multiple species of finches, with as many as ten on some islands.[■]：An introductory sentence for a brief summary of the passage is provided the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage.The geographic isolation of a population can result in the rise of a new species.Answer Choices can result when a geographic barrier forms and splits a population or when a few organisms somehow get carried across an existing geographic barrier and form a new population is more likely when an isolated population is small because significant genetic changes are more likely to occur in a small population than in a large one of the geographic isolation of the Galapagos Islands, the species that now inhabit them have gene pools that have not changed very much since the islands were first populated. populations are more easily isolated by geographic barriers than are populations of most other organisms because fish cannot move across areas where there is no water. Galapagos Islands are well situated for speciation because they provide opportunities for population isolation while also making occasional dispersions between islands possible. indicates that the first organisms to reach the Galapagos Islands were probably a small population of finches that,in less than two million years of isolation,evolved into thirteen species.Explaining Dinosaur ExtinctionDinosaurs rapidly became extinct about 65 million years ago as part of a mass extinction known as the KT event, because it is associated with a geological signature known as the KT boundary, usually a thin band of sedimentation found in various parts of the world (K is the traditional abbreviation for the Cretaceous, derived from the German name Kreidezeit). Many explanations have been proposed for why dinosaurs became extinct. For example, some have blamed dinosaur extinction on the development of flowering plants, which were supposedly more difficult to digest and could have caused constipation or indigestion—except that flowering plants first evolved in the Early Cretaceous, about 60 million years before the dinosaurs died out. In fact, several scientists have suggested that the duckbill dinosaurs and homed dinosaurs, with their plex battery of grinding teeth, evolved to exploit this new resource of rap