在一個小農(nóng)場中發(fā)現(xiàn)了大麥的3個品種。（圖片提供: Devra Jarvis）
這對于農(nóng)業(yè)領(lǐng)域來說是一個好消息：一個國際研究小組發(fā)現(xiàn),，在全球范圍內(nèi)，那些生長在小型農(nóng)場中的農(nóng)作物呈現(xiàn)出了令人驚訝的生物多樣性,。這一發(fā)現(xiàn)預(yù)示著,，保護植物的生物多樣性將成為抵御植物疾病、害蟲和全球氣候變化的有效手段,。
生物多樣性是防止農(nóng)作物流失的一道堅強屏障,。一旦某種植物對于特定疾病表現(xiàn)出很高的易感性，植物育種專家便會利用其變種培育出一種更加“堅強”的品系,?？晒┻x擇的植物品種越多，科學(xué)家成功強化農(nóng)作物抵抗力的幾率就越大,。然而隨著家庭農(nóng)場逐漸被大規(guī)模的機械化農(nóng)業(yè)生產(chǎn)所取代——后者以種植較少差異的農(nóng)作物為主,，科學(xué)家開始越來越關(guān)注這種趨勢對農(nóng)作物生物多樣性帶來的不利影響。
為了衡量家庭農(nóng)場的重要性,，意大利羅馬市生物多樣性研究所的植物學(xué)家Devra Jarvis和同事,，對27種農(nóng)作物——它們分布在5個大陸上的2000多個小農(nóng)場中——進行了調(diào)查。這項研究共耗時近10年,，面積達63600公頃,。令研究人員感到驚訝的是，每個農(nóng)民種植的農(nóng)作物至少都有兩個品種,。在某些地區(qū),，例如越南的水稻農(nóng)場和秘魯?shù)哪臼磙r(nóng)場，農(nóng)民種植的品種竟然達到了60余種,。Jarvis表示：“還有許多生物多樣性可能被我們忽略了,。”研究小組在本周的美國《國家科學(xué)院院刊》（PNAS）網(wǎng)絡(luò)版上報告了這一研究成果。
法國蒙彼利埃市發(fā)育研究所的植物遺傳學(xué)家Jean-Louis Pham認為,，這項研究成果非常重要,，因為它提供了“全面的信息，表明遍布在全球各個大陸上的小農(nóng)場維持著數(shù)量相當(dāng)可觀的農(nóng)作物的遺傳多樣性”,。他指出,，這篇論文涉及的簡單數(shù)據(jù)需要艱辛的努力才可獲得，同時,，毫無疑問,，這一成果將被作為一個重要參考而得到廣泛使用，“它向我們提供了21世紀(jì)初期全球農(nóng)作物多樣性的一個真實狀態(tài)”。（來源：科學(xué)時報 群芳）
生物谷推薦原始出處：
（PNAS）,，10.1073/pnas.0800607105,，Devra I. Jarvis, Toby Hodgkin
A global perspective of the richness and evenness of traditional crop-variety diversity maintained by farming communities
Devra I. Jarvisa,b, Anthony H. D. Brownc, Pham Hung Cuongd, Luis Collado-Panduroe, Luis Latournerie-Morenof, Sanjaya Gyawalig, Tesema Tantoh, Mahamadou Sawadogoi, Istvan Marj, Mohammed Sadikik, Nguyen Thi-Ngoc Huel, Luis Arias-Reyesm, Didier Balman, Jwala Bajracharyao, Fernando Castillop, Deepak Rijalg, Loubna Belqadik, Ram Ranag, Seddik Saidiq, Jeremy Ouedraogor, Roger Zangres, Keltoum Rhribq, Jose Luis Chavezt, Daniel Schoenu, Bhuwon Sthapitv, Paola De Santisa, Carlo Faddaa, and Toby Hodgkina
Abstract
Varietal data from 27 crop species from five continents were drawn together to determine overall trends in crop varietal diversity on farm. Measurements of richness, evenness, and divergence showed that considerable crop genetic diversity continues to be maintained on farm, in the form of traditional crop varieties. Major staples had higher richness and evenness than nonstaples. Variety richness for clonal species was much higher than that of other breeding systems. A close linear relationship between traditional variety richness and evenness (both transformed), empirically derived from data spanning a wide range of crops and countries, was found both at household and community levels. Fitting a neutral "function" to traditional variety diversity relationships, comparable to a species abundance distribution of "neutral ecology," provided a benchmark to assess the standing diversity on farm. In some cases, high dominance occurred, with much of the variety richness held at low frequencies. This suggested that diversity may be maintained as an insurance to meet future environmental changes or social and economic needs. In other cases, a more even frequency distribution of varieties was found, possibly implying that farmers are selecting varieties to service a diversity of current needs and purposes. Divergence estimates, measured as the proportion of community evenness displayed among farmers, underscore the importance of a large number of small farms adopting distinctly diverse varietal strategies as a major force that maintains crop genetic diversity on farm.
