The introduction of non-native species into new environments is often viewed solely as a threat to biodiversity. However, a growing body of evidence suggests that in certain contexts, such introductions can yield significant ecological and economic benefits. This essay argues that deliberate introduction of non-native species should be considered a viable conservation and management tool, based on three key points. First, non-native species can fill ecological niches left vacant by extinct or declining native species, thereby restoring ecosystem functions. For example, in Hawaii, the introduction of the Japanese white-eye bird has helped with seed dispersal for native plants whose original avian dispersers are now extinct, promoting forest regeneration. Second, non-native species can provide economic benefits through new agricultural, aquaculture, or recreational opportunities, thus increasing local livelihoods and reducing pressure on overexploited native resources. In many coastal areas, introduced oyster species have boosted aquaculture yields and created jobs without significantly displacing native shellfish. Third, non-native species often exhibit higher resilience to environmental stressors such as pollution or climate change, which can stabilize ecosystems that would otherwise collapse under changing conditions. For instance, certain introduced grasses in California have proven more drought-resistant than native species, maintaining soil stability and preventing erosion during prolonged dry periods. Therefore, rather than blanket condemnation, a case-by-case assessment of potential benefits should guide policy on species introductions.
🎧 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 reading presents a surprisingly optimistic view of introducing non-native species, but its arguments are flawed when examined closely. First, the claim that introduced species fill vacant niches is misleading. In reality, non-native species often compete with native species for resources rather than simply occupying empty roles. In Hawaii, the Japanese white-eye, far from being a benign seed disperser, has aggressively displaced native birds, such as the 'akepa and 'amakihi, by competing for nectar and insects. Moreover, it spreads invasive plants, disrupting the very forest regeneration it is said to promote. Second, the economic benefits cited are often short-term and overshadowed by long-term costs. The introduced oyster species mentioned may boost aquaculture, but they also introduce diseases that devastate native oyster populations, leading to multi-million dollar losses for local fisheries. Additionally, these non-native oysters can outcompete native species for space and food, reducing overall biodiversity and undermining the resilience of the coastal ecosystem. Third, the supposed resilience of introduced species to stressors is a double-edged sword. While some grasses, like the non-native cheatgrass, are indeed drought-resistant, they are also highly flammable. This trait has increased the frequency and intensity of wildfires in California, destroying native shrublands and threatening human communities. In contrast, native grasses, though less flashy, have co-evolved with local conditions and provide better long-term soil stability without the risk of catastrophic fires. Thus, the reading's arguments fail to withstand scrutiny, and the risks of non-native introductions far outweigh any potential benefits.
📝 Instrucciones de escritura 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).
