The introduction of non-native species into new environments is often viewed with alarm, but a closer examination reveals that such introductions can have significant ecological and economic benefits. This essay argues that the deliberate introduction of non-native species should be embraced as a conservation and economic tool, based on three main reasons. First, non-native species can enhance biodiversity by filling vacant ecological niches. For example, the introduction of the Tamarisk beetle in the southwestern United States has helped control the invasive Tamarisk plant, allowing native willows to thrive and increasing habitat diversity for birds. Second, non-native species often provide substantial economic gains. The cultivation of the Pacific oyster in European waters has created lucrative aquaculture industries, providing jobs and a stable food supply, while also reducing pressure on overexploited native oyster beds. Third, non-native species can increase ecosystem resilience by introducing genetic diversity. When the American bison was reintroduced into European reserves, crossbreeding with local cattle produced hybrids that were more resistant to diseases, thereby strengthening the overall health of the herds. These examples illustrate that, rather than being inherently harmful, non-native species can serve as valuable allies in ecological restoration and economic development.
🎧 听力讲座
🎯 模拟考试环境：先点「播放讲座」听完内容，再作答。听力原文默认隐藏。
The lecture challenges the reading's optimistic view of non-native species, arguing that the purported benefits are often overstated and accompanied by severe unintended consequences. First, while the reading claims that non-native species can fill vacant niches, the lecturer points out that such introductions rarely occur in isolation. Using the Tamarisk beetle example, the lecturer explains that although the beetle controlled Tamarisk, it also consumed native willows, leading to a net loss of bird habitat, not a gain. Thus, the supposed enhancement of biodiversity was illusory. Second, the economic benefits cited in the reading are not sustainable. The Pacific oyster, while profitable initially, has outcompeted native mussels and altered water chemistry, causing costly damage to local fisheries and requiring expensive management. The short-term profits do not offset the long-term economic burdens imposed on the ecosystem and local communities. Third, the idea that non-native species increase genetic resilience is misleading. The crossbreeding between American bison and European cattle produced hybrids that, while disease-resistant, lacked the behavioral adaptations essential for survival in the wild. These hybrids were less able to forage and migrate, leading to higher mortality and reduced overall herd fitness. The lecture concludes that the risks of introducing non-native species far outweigh any speculative benefits, and conservation efforts should focus on preserving native ecosystems rather than altering them.
📝 คำแนะนำการเขียน Summarize the points made in the lecture, being sure to explain how they cast doubt on the specific points made in the reading passage.
📊 TOEFL Integrated Writing Rubric
Content Accuracy: Accurately capture the relationship between lecture and reading
Information Completeness: Cover all key counter-arguments from the lecture
Structure & Coherence: Logical organization and progression
Language Use: Grammar, vocabulary, expression accuracy
Scored 0-30 based on holistic scoring (original 0-5, scaled to 30).
