物种进化是可预测的
文章来源:未知 文章作者:enread 发布时间:2013-07-22 06:57 字体: [ ]  进入论坛
(单词翻译:双击或拖选)
If you could hit the reset1 button on evolution and start over, would essentially2 the same species appear? Yes, according to a study of Caribbean lizards4 by researchers at the University of California, Davis, Harvard University and the University of Massachusetts. The work is published July 19 in the journal Science. The predictability of evolution over timescales of millions of years has long been debated by biologists, said Luke Mahler, a postdoctoral fellow at UC Davis and first author on the paper. For example, the late Stephen Jay Gould predicted that if you "rewound the tape" on evolution and started over, you would get an entirely5 different outcome, arguing that small events -- a storm that wiped out a particular pond, a poor season for insects -- could have a disproportionate effect.
 
On the other hand, there are a number of examples of species in similar habitats that evolve independently into similar-looking forms, such as the cichlid(丽鱼科的) fishes of African lakes.
 
"It's a big question in evolutionary6 biology, but very hard to test," Mahler said.
 
Mahler found his test subjects in the Anole lizards that live on four neighboring islands -- Cuba, Hispaniola (the countries of Haiti and the Dominican Republic), Jamaica and Puerto Rico. Anoles began colonizing7 these islands, all similar in climate and ecology, about 40 million years ago, and once there, they began to multiply, resulting in a diversity of species on each.
 
The researchers studied 100 of the 119 Anole lizard3 species from the islands, taking measurements of their bodies from wild and museum specimens8 and comparing them across islands.
 
They found a striking degree of convergence -- on each island, evolution had produced a set of very similar-looking lizards occupying similar environmental niches10.
 
"The adaptive radiations match on all four islands -- with few exceptions, each species on an island has a match on the other islands," Mahler said.
 
By combining the body-form data with a family tree of the Anoles, Mahler and colleagues were able to construct an "adaptive landscape" for the lizards. An adaptive landscape is a fundamental concept in evolutionary biology but difficult to show in practice. Peaks on an adaptive landscape represent various combinations of features that will be favored by natural selection, whereas valleys are just the opposite. Species with similar habits will tend to cluster on the same peak.
 
For Anole lizards, their niche9 might be living on tree-trunks, or among twigs11 high in a tree, or down in the grasses on the ground. Each calls for different adaptations, and creates a different adaptive peak.
 
The adaptive landscapes of all four islands are very similar, the researchers found. Looking back at the lizards' evolutionary history, they were able to determine when a particular peak was colonized12, or when a species hopped13 from one peak to another. The landscape drives convergence, they discovered.
 
"The cool part is that we now have a way of modeling the adaptive landscape that explains this convergence(收敛,集合)," Mahler said.


点击收听单词发音收听单词发音  

1 reset rkHzYJ     
v.重新安排,复位;n.重新放置;重放之物
参考例句:
  • As soon as you arrive at your destination,step out of the aircraft and reset your wristwatch.你一到达目的地,就走出飞机并重新设置手表时间。
  • He is recovering from an operation to reset his arm.他做了一个手臂复位手术,正在恢复。
2 essentially nntxw     
adv.本质上,实质上,基本上
参考例句:
  • Really great men are essentially modest.真正的伟人大都很谦虚。
  • She is an essentially selfish person.她本质上是个自私自利的人。
3 lizard P0Ex0     
n.蜥蜴,壁虎
参考例句:
  • A chameleon is a kind of lizard.变色龙是一种蜥蜴。
  • The lizard darted out its tongue at the insect.蜥蜴伸出舌头去吃小昆虫。
4 lizards 9e3fa64f20794483b9c33d06297dcbfb     
n.蜥蜴( lizard的名词复数 )
参考例句:
  • Nothing lives in Pompeii except crickets and beetles and lizards. 在庞培城里除了蟋蟀、甲壳虫和蜥蜴外,没有别的生物。 来自辞典例句
  • Can lizards reproduce their tails? 蜥蜴的尾巴断了以后能再生吗? 来自辞典例句
5 entirely entirely     
ad.全部地,完整地;完全地,彻底地
参考例句:
  • The fire was entirely caused by their neglect of duty. 那场火灾完全是由于他们失职而引起的。
  • His life was entirely given up to the educational work. 他的一生统统献给了教育工作。
6 evolutionary Ctqz7m     
adj.进化的;演化的,演变的;[生]进化论的
参考例句:
  • Life has its own evolutionary process.生命有其自身的进化过程。
  • These are fascinating questions to be resolved by the evolutionary studies of plants.这些十分吸引人的问题将在研究植物进化过程中得以解决。
7 colonizing 8e6132da4abc85de5506f1d9c85be700     
v.开拓殖民地,移民于殖民地( colonize的现在分词 )
参考例句:
  • The art of colonizing is no exception to the rule. 殖民的芸术是? 有特例的。 来自互联网
  • A Lesson for Other Colonizing Nations. 其它殖民国家学习的教训。 来自互联网
8 specimens 91fc365099a256001af897127174fcce     
n.样品( specimen的名词复数 );范例;(化验的)抽样;某种类型的人
参考例句:
  • Astronauts have brought back specimens of rock from the moon. 宇航员从月球带回了岩石标本。
  • The traveler brought back some specimens of the rocks from the mountains. 那位旅行者从山上带回了一些岩石标本。 来自《简明英汉词典》
9 niche XGjxH     
n.壁龛;合适的职务(环境、位置等)
参考例句:
  • Madeleine placed it carefully in the rocky niche. 玛德琳小心翼翼地把它放在岩石壁龛里。
  • The really talented among women would always make their own niche.妇女中真正有才能的人总是各得其所。
10 niches 8500e82896dd104177b4cfd5842b1a09     
壁龛( niche的名词复数 ); 合适的位置[工作等]; (产品的)商机; 生态位(一个生物所占据的生境的最小单位)
参考例句:
  • Some larvae extend the galleries to form niches. 许多幼虫将坑道延伸扩大成壁龛。
  • In his view differences in adaptation are insufficient to create niches commensurate in number and kind. 按照他的观点,适应的差异不足以在数量上和种类上形成同量的小生境。
11 twigs 17ff1ed5da672aa443a4f6befce8e2cb     
细枝,嫩枝( twig的名词复数 )
参考例句:
  • Some birds build nests of twigs. 一些鸟用树枝筑巢。
  • Willow twigs are pliable. 柳条很软。
12 colonized b6d32edf2605d89b4eba608acb0d30bf     
开拓殖民地,移民于殖民地( colonize的过去式和过去分词 )
参考例句:
  • The area was colonized by the Vikings. 这一地区曾沦为维京人的殖民地。
  • The British and French colonized the Americas. 英国人和法国人共同在美洲建立殖民地。
13 hopped 91b136feb9c3ae690a1c2672986faa1c     
跳上[下]( hop的过去式和过去分词 ); 单足蹦跳; 齐足(或双足)跳行; 摘葎草花
参考例句:
  • He hopped onto a car and wanted to drive to town. 他跳上汽车想开向市区。
  • He hopped into a car and drove to town. 他跳进汽车,向市区开去。
TAG标签: species evolution peak
发表评论
请自觉遵守互联网相关的政策法规,严禁发布色情、暴力、反动的言论。
评价:
表情:
验证码:点击我更换图片