【OG24-586题】The passage mentions which of the following as a factor that affects the role of P. ochraceus as a keystone species within different habitats?_mofa留学圈mofaGRE在线题库系统_GRE在线搜题_GRE题库解析_GRE真题机经_GRE课程_GRE培训机构

最新题目

题目内容

纠错

While the most abundant and dominant species within a particular ecosystem is often crucial in perpetuating the ecosystem, a "keystone" species, here defined as one whose effects are much larger than would be predicted from its abundance, can also play a vital role. But because complex species interactions may be involved, identifying a keystone species by removing the species and observing changes in the ecosystem is problematic. It might seem that certain traits would clearly define a species as a keystone species; for example, Pisaster ochraceus is often a keystone predator because it consumes and suppresses mussel populations, which in the absence of this starfish can be a dominant species. But such predation on a dominant or potentially dominant species occurs in systems that do as well as in systems that do not have species that play keystone roles. Moreover, whereas P. ochraceus occupies an unambiguous keystone role on wave-exposed rocky headlands, in more wave-sheltered habitats the impact of P. ochraceus predation is weak or nonexistent, and at certain sites sand burial is responsible for eliminating mussels. Keystone status appears to depend on context, whether of particular geography or of such factors as community diversity (for example, a reduction in species diversity may thrust more of the remaining species into keystone roles) and length of species interaction (since newly arrived species in particular may dramatically affect ecosystems).

The passage mentions which of the following as a factor that affects the role of P. ochraceus as a keystone species within different habitats?

The degree to which the habitat is sheltered from waves The degree to which other animals within a habitat prey on mussels The fact that mussel populations are often not dominant within some habitats occupied by P. ochraceus The size of the P. ochraceus population within the habitat The fact that there is great species diversity within some habitats occupied by P. Ochraceus

正确答案： A

参考解析

提交我的解析

文章大意逻辑
文章开篇指出在特定生态系统中，最丰富和占主导地位的物种对维持生态系统很关键，但“关键物种”（keystone species）影响也很大，其影响远超其数量所预示的。接着说明通过移除物种并观察生态系统变化来识别关键物种存在问题。以海葵海星（Pisaster ochraceus ）为例，它常是关键捕食者，能抑制贻贝种群，然而这种对优势物种的捕食在有和没有关键物种的系统中都存在。此外，海葵海星在不同栖息地作用不同，在暴露于海浪的岩石海岸是关键物种，但在更多受海浪庇护的栖息地其捕食影响微弱甚至不存在，某些地方沙埋也会消灭贻贝。最后总结关键物种地位取决于环境，如特定地理环境、群落多样性和物种相互作用时长等。 文章类型及逻辑简图
文章类型：观点阐述型。逻辑简图： 1. Introduction: Most abundant species crucial, keystone species also vital. 2. Problem: Difficulty in identifying keystone species. 3. Example: Pisaster ochraceus as a keystone predator and its varying impacts. 4. Conclusion: Keystone status depends on context. 做题方法及问题类型
问题类型为细节题。做题方法是通过定位关键词“P. ochraceus”“keystone species”“different habitats”，在文中寻找相关因素。定位提示句子为“Moreover, whereas P. ochraceus occupies an unambiguous keystone role on wave exposed rocky headlands, in more wave sheltered habitats the impact of P. ochraceus predation is weak or nonexistent, and at certain sites sand burial is responsible for eliminating mussels.” 选项分析
A选项：栖息地受海浪庇护的程度。文中明确提到海葵海星在暴露于海浪的岩石海岸和更多受海浪庇护的栖息地作用不同，该因素影响其作为关键物种的角色，所以A选项正确。 B选项：栖息地内其他动物捕食贻贝的程度。文中未提及该因素对海葵海星作为关键物种角色的影响，排除。 C选项：在海葵海星占据的一些栖息地中，贻贝种群通常不占主导地位这一事实。文中重点强调的是海葵海星的捕食作用以及栖息地环境对其关键物种角色的影响，而非贻贝是否占主导地位，排除。 D选项：栖息地内海葵海星种群的大小。文章未提及种群大小对其作为关键物种角色的影响，排除。 E选项：在海葵海星占据的一些栖息地中存在很大的物种多样性这一事实。文章虽提到物种多样性对关键物种地位有影响，但未表明在海葵海星占据的栖息地中物种多样性大小这一具体因素对其作为关键物种角色的影响，排除。

题目讨论 (如果对题目有任何的疑惑，欢迎在这里提出来，大家会帮你解答的哦~)

还没有人评论,赶快抢个沙发~

做题笔记

参考解析

题目讨论 (如果对题目有任何的疑惑，欢迎在这里提出来，大家会帮你解答的哦~)

请选择错误类型：

请描述一下这个错误：