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腳底下的線蟲翻轉科學界對動物全球分佈的認知!台大植物病理與微生物學系教授楊爵因參與跨國合作團隊,針對全球土壤線蟲群相進行研究,建立史上第一個可預測全球每平方公里線蟲族群密與食性群相的高解析度地圖,更發現全球線蟲數量及分佈遠超過以往認知,研究成果榮登《自然(Nature)》期刊。

 

    線蟲是世界上數量最多且種類歧異度僅次於昆蟲的動物,尤其寄生性線蟲對於農林業發展具重要性,雖可能造成農業損害,某些種類的的線蟲卻也能攻擊其他害蟲,成為生物防治的利器。此研究計畫由蘇黎世聯邦理工學院主導,利用顯微鏡鑑定物種,共分析6759個土壤樣本,來源橫跨所有大陸,包含極地苔原至熱帶雨林等各種自然生態系,建立具有全球代表性的線蟲群相分佈地圖。

 

    楊爵因表示,研究發現高緯度地區的表土中線蟲具有較高豐富度,且與地面上生物族群的分佈情況完全相反,全球38.7%的土壤線蟲分佈於北美洲、斯堪地那維雅半島與俄羅斯的寒帶森林與苔原中,24.5%分佈於溫帶地區,而僅20.5%於熱帶與亞熱帶。而研究數據顯示,線蟲數量占全球地表生物總量的五分之四,總生物質量達3億公噸,相當於全球77億人口體重總和的8成,遠遠超過以往的認知。

 

    楊爵因進一步說明,該研究也運用機器學習相關技術,分析不同食性線蟲的數量與氣候、土壤、植被間的關係,得到73個變異因子,並將這樣的資訊進一步演算,建立史上第一個可以預測全球每平方公里線蟲族群密與食性群相的高解析度地圖,完成首例涵蓋全球大範圍的劃時代線蟲群相研究。此外,線蟲對於環境中溫度與二氧化碳相當敏感,且與土壤中碳排放密切相關,因此該研究成果未來亦可運用在氣候變遷相關指標的研究。

 

研究成果於108年7月24日刊登在國際頂尖雜誌《自然(Nature)》期刊。

研究全文連結:https://www.nature.com/articles/s41586-019-1418-6

 

圖一:研究使用線蟲樣本地圖與豐富度。(圖片來源/ Nature期刊)

Professor Jiue-In Yang from Department of Plant Pathology and Microbiology participated in a international research group, working on the nematodes in soil around the world. The figure shows the density map of nematodes around the world (from the article in Nature). This research group established the first high-resolution maps in history that can predict the density and feeding groups of nematode populations per square kilometer in the world. They found that the number and distribution of nematodes in the world far exceed previous estimates. The related research results have been published in Nature. Professor Jiue-In Yang said that the nematodes in the topsoil of high latitudes have a higher abundance, which is completely opposite to the distribution of most biological groups in the soil. Around 38.7% of the world’s soil nematodes are distributed in North America, Scandinavia, and Russia's frigid forests and tundra; 24.5% are distributed in temperate regions; and only 20.5% are in tropical and subtropical regions. Research data showed that the number of nematodes accounted for four-fifths of the total surface life of the world, with a total biological mass of 300 million metric tons. This is equivalent to 80% of the total weight of the world's 7.7 billion people, far exceeding previous estimates.

This study also used machine-learning technologies to analyze the relationship between the number of different nematode feeding groups and climate, soil, and vegetation, covering 73 variation factors. This information was further calculated to establish a high-resolution map that can predict the density and feeding groups of nematode populations per square kilometer anywhere in the world. Nematodes are very sensitive to temperature and CO2 in the environment, and are closely related to carbon emissions in the soil. Therefore, the results of this research can also be used in the study of indicators related to climate change in the future.

The research results were published in Nature on July 24, 2019. See full article at

https://www.nature.com/articles/s41586-019-1418-6

Figure.The Map of Nematodes around the World (from the article in Nature)

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