導入された捕食動物は亜北極の島々を草原からツンドラへと変貌させる
D A Croll1, J L Maron, J A Estes
1Department of Ecology and Evolutionary Biology, Island Conservation, University of California-Santa Cruz, Santa Cruz, CA 95060, USA. croll@biology.ucsc.edu
Science (New York, N.Y.)
|March 26, 2005
まとめ
北極キツネの導入は,アレウト諸島の生態系に大きな変化をもたらしました. 海鳥の獲物を減らすことで,キツネは栄養素の輸送を減らし,土壌に影響を与え,植物群を草原から灌木地帯に変えました.
科学分野:
- エコロジー エコロジー エコロジー
- フードウェブのダイナミクス
- 島のバイオジオグラフィー
背景:
- トップの捕食者は獲物の集団に影響を与えますが,より低いトロフィックレベル,特に植物コミュニティへの影響については議論されています.
- 植物全体のコミュニティを変化させるトロフィックカスケードは,陸上の生態系では珍しい.
研究 の 目的:
- 導入された北極のキツネ (Alopex lagopus) がアレウト諸島群の食物網と植物コミュニティに与える影響を調査する.
- 捕食者と獲物の相互作用が陸上の生態系に影響を与える経路を解明する.
主な方法:
- アレウト諸島群島でのフィールド観察と生態調査.
- 捕食者と獲物の関係,特に北極のキツネと海鳥の分析.
- 土壌の栄養分レベルと植物集団の構成の評価.
主要な成果:
- 北極のキツネは海鳥を捕食し,海洋から陸上の環境への栄養素の輸送を大幅に削減しました.
- 栄養素の摂取量が少なくなり,土壌の肥沃性が低下した.
- 植物のコミュニティは草原の優位性から,矮小の灌木/森の優位性のある生態系へと移行した.
結論:
- 導入された北極キツネは,植物コミュニティに重大な影響を及ぼす強力なトロフィックカスケードを生み出しました.
- 肉食動物によって引き起こされる栄養循環の変化は,以前未知の経路で陸上の生態系に影響を与えています.
- この研究は,生態系の構造と機能に対するトップ捕食者の深い間接的な影響を強調しています.
関連する概念動画
00:48Optimal Foraging
How animals obtain and eat their food is called foraging behavior. Foraging can include searching for plants and hunting for prey and depends on the species and environment.
01:50Threats to Biodiversity
There have been five major extinction events throughout geological history, resulting in the elimination of biodiversity, followed by a rebound of species that adapted to the new conditions. In the current geological epoch, the Holocene, there is a sixth extinction event in progress. This mass extinction has been attributed to human activities and is thus provisionally called the Anthropocene. In 2019 the human population reached 7.7 billion people and is projected to comprise 10 billion by...
02:39Predator-Prey Interactions
Predators consume prey for energy. Predators that acquire prey and prey that avoid predation both increase their chances of survival and reproduction (i.e., fitness). Routine predator-prey interactions elicit mutual adaptations that improve predator offenses, such as claws, teeth, and speed, as well as prey defenses, including crypsis, aposematism, and mimicry. Thus, predator-prey interactions resemble an evolutionary arms race.Although predation is commonly associated with carnivory, for...
02:07Conservation of Declining Populations
Conservation of declining population focuses on ways of detecting, diagnosing, and halting a population decline. The approach uses methods to prevent populations from going extinct.
02:31Habitat Fragmentation
Habitat fragmentation describes the division of a more extensive, continuous habitat into smaller, discontinuous areas. Human activities such as land conversion, as well as slower geological processes leading to changes in the physical environment, are the two leading causes of habitat fragmentation. The fragmentation process typically follows the same steps: perforation, dissection, fragmentation, shrinkage, and attrition.
01:05Instinctive Drift
Instinctive drift refers to the tendency of animals to revert to their innate behaviors despite repeated reinforcement. Breland and Breland demonstrated this concept in an experiment with a raccoon. The raccoon was trained to pick up two coins and place them in a container in exchange for food. Initially, the raccoon learned to associate the coins with food, making them a conditioned stimulus or a substitute for food. However, over time, the raccoon became less willing to put the coins into the...