在一个小农场中发现了大麦的3个品种。(图片提供: Devra Jarvis)
这对于农业领域来说是一个好消息:一个国际研究小组发现,在全球范围内,那些生长在小型农场中的农作物呈现出了令人惊讶的生物多样性。这一发现预示着,保护植物的生物多样性将成为抵御植物疾病、害虫和全球气候变化的有效手段。
生物多样性是防止农作物流失的一道坚强屏障。一旦某种植物对于特定疾病表现出很高的易感性,植物育种专家便会利用其变种培育出一种更加“坚强”的品系。可供选择的植物品种越多,科学家成功强化农作物抵抗力的几率就越大。然而随着家庭农场逐渐被大规模的机械化农业生产所取代——后者以种植较少差异的农作物为主,科学家开始越来越关注这种趋势对农作物生物多样性带来的不利影响。
为了衡量家庭农场的重要性,意大利罗马市生物多样性研究所的植物学家Devra Jarvis和同事,对27种农作物——它们分布在5个大陆上的2000多个小农场中——进行了调查。这项研究共耗时近10年,面积达63600公顷。令研究人员感到惊讶的是,每个农民种植的农作物至少都有两个品种。在某些地区,例如越南的水稻农场和秘鲁的木薯农场,农民种植的品种竟然达到了60余种。Jarvis表示:“还有许多生物多样性可能被我们忽略了。”研究小组在本周的美国《国家科学院院刊》(PNAS)网络版上报告了这一研究成果。
法国蒙彼利埃市发育研究所的植物遗传学家Jean-Louis Pham认为,这项研究成果非常重要,因为它提供了“全面的信息,表明遍布在全球各个大陆上的小农场维持着数量相当可观的农作物的遗传多样性”。他指出,这篇论文涉及的简单数据需要艰辛的努力才可获得,同时,毫无疑问,这一成果将被作为一个重要参考而得到广泛使用,“它向我们提供了21世纪初期全球农作物多样性的一个真实状态”。(来源:科学时报 群芳)
生物谷推荐原始出处:
(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.