跟讀練習: What is a Keystone Species? - Wild Education - 通過影片學習英語口語
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49 句
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Have you ever wondered why the loss of just one species can completely transform an entire ecosystem?
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The answer often lies in something called a keystone species.
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A keystone species is a species that has a disproportionately large effect on its ecosystem relative to its abundance or biomass.
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In other words, its influence on the ecosystem is much greater than you would expect based on how common it is.
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The term comes from architecture.
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A keystone is the central stone at the top of an arch that holds all the other stones in place.
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Remove the keystone and the arch can collapse.
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In ecology, removing a keystone species can also lead to major changes in ecosystem structure and function.
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So how does this happen?
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Keystone species help maintain the balance of ecosystems in different ways.
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Some are top predators that regulate prey populations.
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Others are ecosystem engineers that physically modify habitats, creating conditions that benefit many other species.
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One of the best known examples is the sea otter.
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Sea otters feed on sea urchins, which graze on kelp.
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When the sea otter populations decline, sea urchin numbers can increase dramatically.
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Large numbers of sea urchins can overgraze kelp forests, reducing these important underwater habitats.
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Since kelp forests provide food, shelter and breeding areas for hundreds of marine species,
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the loss of sea otters can have widespread effects throughout the ecosystem.
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Another famous example is the grey wolf in Yellowstone National Park.
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Wolves were eradicated from the park during the early 20th century allowing elk populations to grow
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and spend more time grazing in sensitive areas.
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This heavy browsing reduced the regeneration of trees such as willow and aspen in some parts of the park.
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After wolves were reintroduced in 1995
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they helped reduce elk numbers and changed elk behaviours meaning they spent less time feeding in certain areas.
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Along with other factors, including changes in the climate and the recovery of other species, this allowed vegetation to recover in many locations.
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As habitats improved, species such as beavers, birds, insects and fish also benefited.
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This is an example of a trophic cascade, where changes at one level of a food web influence multiple other levels.
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Not all keystone species are predators.
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The African elephant is often described as a keystone species because it shapes entire landscapes.
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By pushing over trees, creating clearings, digging for water during dry periods and dispersing seeds in its dun,
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elephants create habitats and resources that support many other plants and animals.
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Another excellent example is the beaver.
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Beavers are known as ecosystem engineers because they build dams that create wetlands.
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These wetlands provide habitat for fish, amphibians, reptiles, birds, mammals, aquatic plants and countless invertebrates.
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Beaver dams can also slow water flow, improve water storage,
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reduce downstream flooding and help trap sediment and nutrients it's important to remember
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that keystone species aren't always the largest the rarest
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or the most abundant organisms in an ecosystem what makes them unique is
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that removing them causes much greater ecological changes than would be expected from their numbers alone
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this is why conserving keystone species is so important
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so to summarize a keystone species is one whose impact on an ecosystem is far greater than its abundance would suggest.
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By protecting them conservationists can help maintain biodiversity,
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support healthy ecosystem processes and protect many other species that depend directly
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or indirectly on the habitat and ecological interactions they help sustain.
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Whether it's a sea otter protecting kelp forests, a wolf influencing food webs,
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an elephant shaping landscapes, or a beaver creating wetlands.
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These species play a vital role in maintaining healthy, resilient ecosystems.
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Understanding keystone species helps us appreciate just how interconnected nature really is,
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and why the loss of.. even a single species can sometimes have consequences that ripple throughout an entire ecosystem.
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推薦影片
本課的詞彙與口語要點
這節口語課以影片“What is a Keystone Species? - Wild Education”為素材。 影片中反覆出現的詞有:species, ecosystem, keystone, sea, habitat。 這段影片共有 49 個句子、635 個單詞可供跟讀。 講話部分時長為 5:06。 說話人語速平穩,每分鐘約 125 個詞,很適合跟讀。 只有 71% 的單詞屬於英語最常用的 3,000 詞,詞彙難度較高。
影片中的重點詞彙
影片中 15 個值得學習的單詞,附發音和釋義:
| 單詞 | 發音 | 釋義 |
|---|---|---|
| ecosystem 名詞 | /ˈikoʊˌsɪstəm/ | 生態系 /生態系, 生態系統 /生態系統 |
| beaver 名詞 | /ˈbivɚ/ | 海狸, 河狸 |
| wolf 名詞 | /wʊlf/ | лон, мулон |
| elephant 名詞 | /ˈɛlɪfənt/ | щён, 象 |
| landscape 名詞 | /ˈlan(d)skeɪp/ | 風景 /風景, 景色 |
| dam 名詞 | /ˈdæm/ | бэ, фибэ |
| arch 名詞 | /ɑɹt͡ʃ/ | 拱形, 拱 |
| ecological 形容詞 | /ˌiːkəˈlɒd͡ʒɪkl̩/ | 生態的 /生態的, 生態學的 /生態學的 |
| predator 名詞 | /ˈpɹɛd.ə.tɚ/ | 掠食者, 天敵 /天敵 |
| relative 名詞 | /ˈɹɛl.ə.tɪv/ | 親戚 /親戚 |
| sensitive 形容詞 | /ˈsɛn.sɪt.ɪv/ | 敏感 |
| architecture 名詞 | /ˈɑː.kɪˌtɛk.t͡ʃə/ | 建築 /建築, 建築學 /建築學 |
| decline 動詞 | /dɪˈklaɪn/ | 惡化 /惡化 |
| resource 名詞 | /ɹɪˈzɔːs/ | 資源 /資源 |
| vital 形容詞 | /ˈvaɪtəl/ | 生命的 |
需要注意的發音
- “sh” 和 “zh” 音: interaction /ˌɪn.təˈɹæk.ʃən/, shelter /ˈʃɛltə/, vegetation /ˌvɛd͡ʒəˈteɪʃən/, disproportionately /ˈdɪs.pɹəˌpɔɹ.ʃən.ət.li/
- 長單詞——注意重音位置: ecosystem /ˈikoʊˌsɪstəm/, ecological /ˌiːkəˈlɒd͡ʒɪkl̩/, architecture /ˈɑː.kɪˌtɛk.t͡ʃə/, interaction /ˌɪn.təˈɹæk.ʃən/, underwater /ʌndɚˈwɔtəɹ/
中文母語者容易讀錯的音:
- /v/ — 不要讀成 /w/,上齒輕觸下唇: beaver /ˈbivɚ/, relative /ˈɹɛl.ə.tɪv/, sensitive /ˈsɛn.sɪt.ɪv/, vital /ˈvaɪtəl/, recover /ɹɪˈkʌvɚ/
- 詞尾子音 — 要讀清楚,後面不要加母音: habitat /ˈhæb.ɪ.tæt/, wolf /wʊlf/, elephant /ˈɛlɪfənt/, landscape /ˈlan(d)skeɪp/, arch /ɑɹt͡ʃ/
- /r/ 和 /l/ 的區別: relative /ˈɹɛl.ə.tɪv/, clearing /ˈklɪɹɪŋ/, regulate /ˈɹɛɡ.jə.leɪt/, indirectly /ˌɪn.dɪˈɹɛk(t).li/, disproportionately /ˈdɪs.pɹəˌpɔɹ.ʃən.ət.li/
如何用這段影片練習
- 先完整聽一遍影片,不要開口,記下不認識的單詞。
- 用正常速度逐句跟讀,每句重複到你的節奏與說話人一致為止。
- 錄下自己的聲音並與原聲對比,特別注意 ecosystem, beaver, wolf 這類單詞。
什麼是跟讀法?
跟讀法 (Shadowing) 是一種有科學依據的語言學習技巧,最初開發用於專業口譯員的培訓,並由多語言者Alexander Arguelles博士普及。這個方法簡單而強大:您在聽英語母語原聲的同時立即大聲重複——就像是一個延遲1-2秒緊跟說話者的影子。與被動聽力或語法練習不同,跟讀法強迫您的大腦和口腔肌肉同時處理並模模擬實的講話模式。研究表明它能顯著提高發音準確性,語調,節奏,連讀,聽力理解和口語流利度——使其成為雅思口語備考和真實英語交流最有效的方法之一。











