全世界の両生類の人口が減少していることの定量的な証拠
J E Houlahan1, C S Findlay, B R Schmidt
1Ottawa-Carleton Institute of Biology, University of Ottawa, Ontario, Canada. jeffhoul@science.uottawa.ca
Nature
|April 28, 2000
まとめ
世界の両生類の個体数は,特に1960年代から著しく減少しています. 地理的な差異にもかかわらず,この傾向は数十年にわたって持続し,世界中の両生類の保全活動に影響を与えています.
科学分野:
- 生態学と保全生物学 生態学と保全生物学
- 動物学 動物学
- 環境科学 環境科学
背景:
- 両生類の人口減少に関する世界的な懸念が高まっている.
- 現存する証拠は,しばしば逸話的なデータや,限られた規模で短期的な研究に基づいている.
- 自然の人口の変動性による長期的な傾向を検出することや,ローカルデータからグローバルなパターンを推論することの課題.
研究 の 目的:
- 両生類の人口動向における大規模な時間的,空間的変動を評価する.
- 世界的に両生類の人口動態のより堅実な理解を提供するために.
- 地域研究から世界の動向を推論する際の妥当性を検討する.
主な方法:
- 世界各地の936の両生類集団のデータを活用した.
- 異なる地理的地域における時間的な傾向を分析した.
- 数十年にわたる人口動態の空間的変動を調べた.
主要な成果:
- 1950年代後半から1960年代初頭から1960年代後半まで,世界の両生類の急速な減少が観察されました.
- 1960年代後半から現在までの減少率の低下を指摘した.
- 1960年代,西ヨーロッパと北米で否定的な傾向を特定し,北米の人口は1990年代後半まで減少し続けました.
結論:
- 全世界で両生類の個体数は減少しており,その傾向は数十年にわたって明らかになっています.
- 大規模な両生類の集団の傾向は,地理的および時間的に有意な変動を示しています.
- この結果は,両生類の継続的な監視と保全戦略の必要性を強調しています.
関連する概念動画
00:57Population Growth
Population size is dynamic, increasing with birth rates and immigration, and decreasing with death rates and emigration. In ideal conditions with unlimited resources, populations can increase exponentially, which plots as a J-shaped growth rate curve of population size against time. This type of curve is characteristic of newly-introduced invasive species, or populations that have suffered catastrophic declines and are rebounding.However, realistic environmental conditions limit the number of...
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...
01:57What is Conservation Biology?
Conservation biology is a scientific field that focuses on the preservation of biodiversity in order to protect ecosystems while meeting the needs of the human population. Humans require properly functioning ecosystems to maintain our supply of natural resources, including food, medicines, and building materials.
02:04Conservation of Small Populations
Small population sizes put a species at extreme risk of extinction due to a lack of variation, and a consequent decrease in adaptability. This weakens the chances of survival under pressures such as climate change, competition from other species, or new diseases. Large populations are more likely to survive pressures such as these, as such populations are more likely to harbor individuals that have genetic variants that are adaptive under new stresses. Small populations are much less likely to...
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.