Name: how humans change biodiversity
Uploaded: 2019-03-11T09:21:43.000Z
Duration: 1 min 50 s
Channel: JoVE

K12 Standards

north-carolina-k-12-science-standard-course-of-study

North Carolina K-12 Science Standard Course of Study

9-12

Biology

ecosystems-interactions-energy-and-dynamics

Ecosystems- Interactions, Energy, and Dynamics

LS.Bio.5.2

Threats to Biodiversity

絶滅率(画面左)古生代 中世代 新生代(画面下部)生物の多様性は 地質学的な時代の推移を通して、変化してきましたが 5つの大規模な絶滅により 地球上の歴史において 繁栄と衰退を繰り返しました。完新世の絶滅"として知られる 6番目の大規模な絶滅が 人間の営みにより発生しようとしています。人口の爆発的増加が 現代における生物多様性の喪失の主な原因であり 住処がなくなる、過剰な自然の搾取 環境を破壊する種が住みつき始める、地球温暖化などの現象を発生させています。人間の食物と住居に対する需要の急激な増加が 多くの種の住処を奪っています。森林伐採や農耕地の開拓により 他の種がもともとの住処から追いやられ 狭くて限られた場所で生きることを余儀なくされています。他の種にとっての資源も少なくなり、生き残りが厳しくもなっています。食用や医療に利用されている種は 持続可能な範囲を越えて過剰に搾取されています。種の生殖が追い付くための許容範囲を超える経済的需要により この現象は引き起こされています。さらに、環境を破壊する種の登場により 生態系に大きな変化が起こり 破壊行動により、もともと住みついていた種を 減少させ、資源獲得の競争が発生しています。捕食者が存在しないため、環境を破壊する種が生物多様性を急激に減少させています。最後に、二酸化炭素やその他の温室効果ガスの 世界的な排気量の増加により 地球の平均気温が 徐々に増加しています。この現象により、多くの種にとっての 居住可能な地域が減少し、移住やその他の季節性を伴う行動に変化を起こしました。

McLeman, Robert A., Juliette Dupre, Lea Berrang Ford, James Ford, Konrad Gajewski, and Gregory Marchildon. "What We Learned from the Dust Bowl: Lessons in Science, Policy, and Adaptation." Population and Environment 35, no. 4 (2014年6月1日): 417–40.[<a href="https://doi.org/10.1007/s11111-013-0190-z" target="__blank">ソース</a>]

ドブソン、アンディP.「イエローストーンオオカミと自然システムを構成する力」 PLoS Biology 12、no.12(2014年12月23日)。[<a href="https://doi.org/10.1371/journal.pbio.1002025" target="__blank">出典</a>]

Bar-On、Yinon M.、Rob Phillips、およびRon Milo.「地球上のバイオマス分布」 全米科学アカデミー紀要 115、no.25(2018年6月19日):6506。[<a href="https://doi.org/10.1073/pnas.1711842115" target="__blank">ソース</a>]

生物多様性への脅威

地質学的な歴史の中で、生物多様性が失われた後、新しい環境に適応した種が復活するという5つの大きな絶滅イベントがありました。現在の地質学的エポックである完新世では、6回目の絶滅イベントが進行中です。この大量絶滅の原因は人間の活動にあるとされているため、暫定的に「人新世（アントロポセン）」と呼ばれています。2019年には人類の人口は77億人に達し、2060年には100億人になると予測されています。その影響を示すように、バイオマス（特定の種の実際の量）で見ると、地球上の哺乳類の36％をヒトが占め、家畜は60％、野生の哺乳類はわずか4％です。また、鳥類の約70％は家禽類なので、野生の鳥類はわずか30％です。
 
 人間が生物多様性や気候に与える影響を最小限に抑えるためには、私たちの活動のうちどれが問題なのかを理解し、将来の世代のための持続可能な計画を立てて、人類の文明のニーズと進歩のバランスを取る必要があります。生物多様性への主な脅威としては、人間の開発による生息地の喪失、過剰な農業、工場や自動車からの二酸化炭素排出量の増加などが挙げられます。 
 
 <h4>ケーススタディ</h4> 
 
 人間が気象に与える影響の事例としては、1930年代に起こった「ダストボウル」と呼ばれる出来事が挙げられます。1920年代から30年代にかけて、多くの農民が大平原に移り住み、根の張り方が浅い作物を植えるために、自生している地被植物を取り除く皆伐を行いました。カンザス州とテキサス州北部を中心に、北はカナダ、南はテキサス州まで、極端な干ばつと不適切な農法が重なり、北東部の州まで砂嵐が吹き荒れました。最終的には、これらの嵐と不幸にも重なった不景気のために、一般的な食糧不足に陥り、多くの家族が農地を放棄せざるを得なくなりました。自然に適応していない単一の植物種を土地が支えるためには、生物多様性の損失を考慮して農場を計画しなければならないことが明らかになりました。 
 
 もう少し過激な例として、アメリカのイエローストーン国立公園があります。人間の西への移動が始まってから、オオカミの個体数が激減しました。その結果、プロングホーンやミュール鹿などの獲物となる動物の数が増えました。これらの動物はヤマナラシの若い苗木を食べる傾向があるため、ヤマナラシの木が減少しました。その結果、土地の侵食が進み、鳥やその他の動物の生息地が失われていくのです。この一連の流れを裏付けるように、最近イエローストーンにオオカミが再導入され、公園内のヤマナラシの個体数が回復したことが観測されています。この相関関係が、オオカミの再導入によってヤマナラシが活性化したことを示しているとすれば、この研究は、頂点（トップ）の捕食者が生態系の生物多様性に不可欠であるという一般的な概念を補強するものです。
 
 生物多様性の維持は、生態系のバランスを保ち、予測可能な気象パターンを長持ちさせ、新しい工業製品や医療製品の研究のための原材料を確保するために不可欠です。

地質学的な歴史を通じて、生物多様性の消滅をもたらし、その後に種の回復をもたらす5つの主要な絶滅イベントがありました...

Education

JoVE Core

生物学

Ecology

生態学

Biodiversity and Conservation

生物多様性と保全

KEY TERMS AND CONCEPTS

主要用語と概念

how humans change biodiversity

Human activity is changing biodiversity and pushing Earth toward a sixth extinction event. Earlier mass extinctions ended many species, and then new species spread into the changed environment. Today, the Holocene epoch is seeing a mass extinction linked to human actions, and it is often called the Anthropocene.

Human numbers and human biomass show how large this impact has become. In 2019, the human population reached 7.7 billion and is projected to rise to 10 billion by 2060. By biomass, humans make up about 36% of Earth’s mammals, livestock make up 60%, and wild mammals only 4%. About 70% of all birds are poultry, so only 30% are wild birds.

Several common activities threaten biodiversity. Habitat loss can happen when land is cleared for human development. Over-farming can also damage ecosystems. In addition, factories and vehicles release carbon dioxide, which adds to climate problems. To reduce these effects, people need to understand which activities cause harm and find a sustainable balance between human progress and the needs of future generations.

The Dust Bowl is one clear case of human impact on land and weather. In the 1920s and 1930s, many farmers moved to the Great Plains and clear cut the land. They removed native ground-cover plants so they could plant crops with shallow roots. Then extreme drought and poor farming practices combined to create dust storms that spread debris as far as the northeastern states. Food shortages followed, and many families had to leave their farms.

The Dust Bowl shows that farmland must be planned carefully if it is to support single crop species that are not naturally adapted to the area. A different example comes from Yellowstone National Park. After people moved west, wolf populations dropped sharply. Prey animals such as pronghorn and mule deer increased, and they ate young Aspen saplings. Aspen trees declined, which led to more erosion and less habitat for birds and other animals.

Wolves were later reintroduced to Yellowstone, and the Aspen population has since shown a rebound. If this pattern is truly caused by the return of wolves, it supports the idea that apex predators help keep ecosystems balanced. Biodiversity also matters because it helps preserve stable ecosystems, supports more predictable weather patterns, and keeps raw material available for new industrial and medical products.

How Humans Change Biodiversity

what is weather?

How Sunlight Shapes Daily Weather

Weather is the current state of the atmosphere at a specific time and place. It is temporary and changes from one location to another. Weather is shaped by the interaction of the sun, atmosphere, hydrosphere, and geosphere. Solar radiation reaches Earth and interacts with water and land. These surfaces release that energy as thermal radiation, or heat, which warms the air above them. Some of that heat escapes back into space, but some is trapped by atmospheric gases. This heat retention is...

global climate change

Ancient Clues to Climate Change

Ancient climate clues help scientists track global climate change. Paleoclimatology is the study of climate conditions in Earth’s past and the causes and effects behind them. By comparing recent climate patterns with older records, researchers can find strong evidence for human-caused warming. Earth’s climate has changed many times over its 4.5 billion year history. In the last 650,000 years, there have been seven cycles of glacial advance and retreat. The most recent ice age ended more than...

what is biodiversity?

Biodiversity Across Genes, Species, and Ecosystems

Biodiversity is the variety of living things at the genetic, species, and ecosystem levels. It includes not only how many kinds of organisms exist, but also how they are related and how they interact with the world around them. Species diversity spans the full evolutionary tree. It includes single-celled prokaryotes such as bacteria and archaea, as well as the eukaryotic kingdoms: plants, animals, fungi, and protists. About 1.75 million species have been identified so far, and scientists...

threats to biodiversity

Human activity is changing biodiversity and pushing Earth toward a sixth extinction event. Earlier mass extinctions ended many species, and then new species spread into the changed environment. Today, the Holocene epoch is seeing a mass extinction linked to human actions, and it is often called the Anthropocene. Human numbers and human biomass show how large this impact has become. In 2019, the human population reached 7.7 billion and is projected to rise to 10 billion by 2060. By biomass,...

conservation of declining populations

Saving Species Through Population Recovery

Conservation of declining populations focuses on detecting a population drop, finding its cause, and stopping further loss. The goal is to prevent extinction by using scientific methods to identify the agents behind the decline. Once the cause is known, conservation teams can remove, oppose, or neutralize it. A common step is to test possible causes with a small trial group. If the cause is confirmed, the remaining animals may be moved to an unaffected area. When the population is too small or...

biodiversity and human values

Biodiversity in Food, Tools, and Medicine

Biodiversity supports human life through food, tools, medicine, and many other needs. Changes in the variety of species can also change the environment. Those environmental shifts can alter weather patterns and affect human civilizations. People have depended on biodiversity for agriculture since early human history. Agriculture began when ancestral humans found species that were good sources of food. At least 11,000 years ago, people started selecting plant and animal species to raise on...

what is conservation biology?

Protecting Biodiversity in Conservation Biology

Conservation biology is the science of protecting biodiversity and keeping ecosystems healthy. It looks at how living things, habitats, and human needs are connected. The goal is to preserve biodiversity so ecosystems can continue to function well. Healthy ecosystems provide people with important natural resources. These include food, medicines, and building materials. Ecosystems also deliver key services, such as cleaning air and water. Evidence shows that these services depend on...

what is climate?

Climate Patterns and Earth’s Energy Balance

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sustainable development

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conservation of small populations

Saving Small Populations with Genetic Diversity

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habitat fragmentation

How Fragmented Habitats Affect Wildlife

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key terms and concepts

Learn how human population growth, habitat loss, over-farming, and carbon emissions affect biodiversity. Includes the Dust Bowl and Yellowstone wolf example.

How Humans Change Biodiversity | JoVE K12

JoVE Core series brings biology to life through over 300 concise and easy-to-understand animated video lessons that explain key concepts in biology, plus more than 150 scientist-in-action videos that show actual research experiments conducted in today’s laboratories.

biology

JoVE Core シリーズは、生物学の重要な概念を説明する 300 を超える簡潔でわかりやすいアニメーション ビデオ レッスンに加え、今日の研究室で行われる実際の研究実験を示す 150 以上の科学者の活動ビデオを通じて、生物学に命を吹き込みます。

How Humans Change Biodiversity

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