第六次物种大灭绝? 物种从来都是come and go ! 现在美国人基于脊椎动物物种灭绝提速百倍说第六次物种大灭绝已经开始了合理么? 不合理!迄今尚不能明确究竟有多少物种,估计有两万种左右。 仅以脊椎动物物种灭绝提升就说第六次物种大灭绝已经开始显然是不合理的。首先我们必须搞清楚世界上究竟还有多少物种,即物种的确切数量,搞清楚脊椎动物物种究竟会占到多少,是不是主要物种和多数物种,如果是,脊椎动物物种灭绝提速让人担心物种多样性的急剧减少。 物种之间也存在生态平衡现象,自然界中,某些物种的灭绝势必会相应有益于其他物种的繁殖。特别是优势物种之间的制衡被打破之后,比如一二三四五,上山打老虎,人灭绝了,老虎会相应增多...但反过来不一定成立,老虎越来越少,其他在老虎之下的物种数量会相应增加... 物种大灭绝的条件不符合这种物种之间的调整。第六次物种大灭绝只能是气候等非生物因素的彻底改变。但就目前人的智力进步来看,包括气候改变在内的非生物因素的改变很难灭绝人类。
原文出处: http://www.livingalongsidewildlife.com/2013/12/10-animals-that-went-extinct-in-2013.html 作者: David Steen Our extinction crisis continues; 2013 allowed us to safely conclude that we will never again see the animals listed below ( 2012 version here ). One of the last known photos of a Formosan Clouded Leopard; taken by Torii Ryūzō. The Formosan Clouded Leopard ( Neofelis nebulosa brachyura ) of Taiwan is now thought to be extinct . None have been seen in over thirty years, despite a recent and intensive 13-year effort to document one. We did just about everything we could to eliminate this animal; we destroyed their habitat, killed them for their skins, and got rid of the other animals they normally ate. They didn't have a chance. The Cape Verde Giant Skink ( Chioninia coctei ) , which hasn't been seen since 1912, has been declared extinct , although a jawbone from one of these lizards was found in some cat scat in 2005. However, since then the cat (i.e., house cat) population has increased substantially and, aided by rats and dogs, has likely wiped out the skink. The Sri Lanka Spiny Eel ( Macrognathus pentophthalmos ) is probably extinct . As recently as 1980 the species was considered common but it was likely done in by a non-native species of fish that ate many of them. The Eskimo Curlew ( Numenius borealis ) was once so abundant that the sizes of its flocks were compared to those of Passenger Pigeons. They now have something else in common. The last known Eskimo Curlew was observed in 1963; Canada is likely to decide it is officially extinct because it has been 50 years since one has been seen. Eskimo Curlews probably suffered from a decline in their locust prey as well as loss of habitat but the primary cause of extinction is thought to be overhunting. Indeed, the last known Eskimo Curlew was shot by a hunter in Barbados. The Southern Darwin's Frog (i.e., not the extinct one); by Mono Andes, Wikimedia . This year, scientists concluded that the Northern Darwin's Frog ( Rhinoderma rufum ), known only from Chile, is extinct . Closely related to the Southern Darwin's Frog ( Rhinoderma darwinii ), it was only recognized as a distinct species in 1975. The last one ever seen alive was found just five years later, in 1980. Fascinatingly, males of both of these frogs hold (er, held, in the case of R. rufum ) their tadpoles inside of them, as if they were pregnant (think seahorses). Based on previous sightings of these species and intensive surveys where they were known to occur, a group of researchers from Chile and the UK estimated that R. rufum blinked out in 1982. They were cautious though, and suggest in their study that the species should be considered critically endangered (and only possibly extinct). Maybe some frogs are still hanging on somewhere. The Santa Cruz Pupfish ( Cyprinodon arcuatus ) of Arizona has been declared extinct . This small fish was probably once found in a few small wetlands that disappeared due to water management practices that dried them up. The last (and only?) spring known to harbor the species was altered into a pond and canal many years ago. The altered habitats were then invaded by predatory bass, which did their part by eating a bunch of pupfish. A freshwater shrimp ( Macrobrachium leptodactylus ) from Indonesia found once in 1888 and never since has been declared extinct . The area where the shrimp was discovered has been heavily developed. This is a madtom, but not a Scioto Madtom; image by Ellen Edmonson and Hugh Chrisp. The Scioto Madtom ( Noturus trautmani ) , a small catfish known from Ohio, has been declared extinct . The species hasn't been found since 1957. Habitat degradation is the likely cause: runoff and increased siltation degraded the streams the madtom called home. Two butterflies known only from South Florida, the Zestos Skipper ( Epargyreus zestos oberon ) and the Rockland Grass Skipper ( Hesperia meskei pinocayo ) are likely extinct . Habitat loss and modification are probably to blame for the extinction of these two butterflies. The Western Black Rhinoceros ( Diceros bicornis longipes ) was declared extinct in 2011 but for some reason it received a lot of press in late 2013. Here is a comprehensive breakdown of how we lost this magnificent beast . It is just unfathomable, if not unconscionable, that we are responsible for causing a single species to completely disappear from the planet forever. Yet, we continue to do so over and over again. Extinct species have no future, they are gone to us and everyone that comes after us. Let's hope that our 2014 list is shorter than this year's. Did I leave something out? Let me know below. To learn about species on the brink of extinction, do not miss John Platt's excellent blog: Extinction Countdown . Check Out The Following Scientific Article For More on Darwin's Frogs: Soto-Azat C, Valenzuela-Sánchez A, Collen B, Rowcliffe JM, Veloso A, Cunningham AA (2013). The population decline and extinction of Darwin's frogs. PloS one, 8 (6) PMID: 23776705
继何芳良2011年5月19日在Nature上发表“ Species–area relationships always overestimate extinction rates from habitat loss.pdf ”宣称物种灭绝速率被严重高估之后,又有人在PLoS Biology上公布了类似的结果(也是5月),他们在南非开普地区的植物种类调查中发现,植物虽然在灭绝,但也有新种产生,在评估植物物种灭绝风险时这两个因素应该同时考虑进去。链接: Extinction Risk and Diversification Are Linked in a Plant Biodiversity Hotspot . 去年10月召开的生物多样性会议公布了由英国皇家植物园和IUCN的相关机构的调查报告,报告指出全球有超过20%的植物物种面临灭绝的危险,而现在邱园的工作人员又认为情况没那么糟糕,这就提出了一个紧迫的问题:如何评估物种的灭绝等级?这里我指的是具体的某一个植物物种。虽然IUCN制定了评价物种保护级别的标准,但相对粗糙,还没有达到量化的程度。 可喜的是,澳大利亚阿德莱德大学的科研人员发明了一种定量评价物种受威胁程度的指数——SAFE Index(Species Ability to Forestall Extinction, 我把他翻译成“ 物种抗灭绝指数 ”,不知是否恰当,请相关专家指正!)。他们的文章发表在Frontiers in Ecology and the Environment (IF=6.922)上,但好像用来评价哺乳动物的。链接: The SAFE index: using a threshold population target to measure relative species threat .
生物多样性丧失产生了一门学科,保护生物学,保护生物学是研究如何保护物种的,包括植物、动物等。如果一个物种确认处在濒危状态,它就应该受到优先保护。然而,我们也仅仅保护这些处于濒危状态的物种,事实上,任何物种都有生存的权利,就像“法律面前人人平等”、“人生来都是平等的”一样,每个物种都是大自然的子女。 越来越多的研究表明,生物多样性正在以前所未有的速度丧失,生物多样性没有了,人类会更加孤独、可利用的资源更少,最后或许只能自娱自乐了。可最近的研究发现还不止这些,生物多样性的减少还会严重危险人类健康,人类不仅孤独还会受到更多疾病的折磨。同时,科学家发现生物多样性是整个生态系统维持正常运转的基础,生物多样性较低的生态系统无论在氧气产量、初级净生产物积累还是稳定性、高效性上都不如生物多样性丰富的生态系统,我觉得人们可以改变基于自身利益的生物保护理念,如优先保护生物学的短视行为。 然而,物种为什么会灭绝呢?其实灭绝的原因很简单。无论是研究哪个物种的,无论是采用什么样的模型,也无论是否有详尽的数据,文献中普遍得出相似的结论。物种灭绝、生物多样性锐减的原因主要有人为干扰导致的生境片段化、气候变化和地质运动等,有时这些因素又是协同的。不同研究方向的人研究侧重点有可能不同,所以分析的结果又可能不同,但这些原因已经得到人们的普遍认同(构建的保护策略也大同小异)。觉得好玩,我总结了濒危物种的濒危原因的一句话,刚才在听中科院 李明研究员 报告时分享给了他,他觉得也有一定的道理。这句话算是我近几年工作的总结,“ 濒危物种的濒危原因都是一样样的,不濒危物种各有各的不濒危原因 ”。有时,复杂的科学研究就是这么回事,道理都是简单的,真理都是朴素的。 参考文献: Felicia Keesing, Lisa K. Belden, Peter Daszak, et al. Impacts of biodiversity on the emergence and transmission of infectious diseases. Nature , 2010, 468(7324): 647-652. Bradley J. Cardinale, Kristin L. Matulich, David U. Hooper, et al. The functional role of producer diversity in ecosystems. American Journal of Botany , 2011, 98(3): 1-21.