中美发现两种新蜜蜂
文章来源:未知 文章作者:enread 发布时间:2011-10-19 05:30 字体: [ ]  进入论坛
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Smithsonian scientists have discovered two new, closely related bee species: one from Coiba Island in Panama and another from northern Colombia. Both descended1 from of a group of stingless bees that originated in the Amazon and moved into Central America, the ancestors of Mayan honeybees. The presence of one of these new species on Coiba and Rancheria Islands, and its absence from the nearby mainland, is a mystery that will ultimately shed light on Panama's history and abundant biodiversity. At almost 200 square miles, Coiba Island is the largest offshore2 island along the Pacific coast of Latin America. Rancheria Island is a much smaller neighbor. The species name, insularis, of the new bee from Coiba, Melipona insularis, means "island." This is the first species in its group to be found on islands near the mainland.

"These forest bees have a small range over which they can establish new nests and colonies," says David Roubik, staff scientist at the Smithsonian Tropical Research Institute. "They can't establish a new nest across more than a short stretch of open water because workers from the original nest have to build and supply the new nest before the new queen moves in."

Either several entire tree-cavity nests arrived on Coiba and Rancheria in floating mats of vegetation or a land connection existed between the island and the mainland before the bees disappeared from the mainland.

Sea level has risen and fallen dramatically in the past. During ice ages, when much of Earth's water is locked up in polar caps and glaciers3, sea level drops in Panama. The sea floor between Coiba and the mainland, and between Coiba and neighboring Rancheria Island where the bee was also found, is never more than about 300 feet below the surface. Five other stingless bee species on Coiba are widespread on the mainland and on many little islands that were connected to the mainland during glaciations. Those bees are relative newcomers that may have arrived during past drops in sea level when the islands were reconnected to the mainland.

Roubik thinks the ancestors of Melipona (Melikerria) ambigua, the new species from Colombia, gave rise both to the new Coiba bee and the honeybees cultivated by Mayans in Mexico and Central America. Even if a drop in sea level explains how the bees got from the mainland to the island, their discovery that the bees had already established in Central America around 17 million years ago spurs an ongoing4 debate about the age of the connection between North and South America. Traditionally, geologists5 think that the Panama land bridge arose by tectonic(构造的) and volcanic6 action to connect the two continents about 3 million years ago.

"Our studies of the genetic7 relationships between these bees tells us that they originated in the Amazon about 22 million years ago and that they moved north into Central America before 3 million years ago," said Roubik. "This actually agrees with new evidence that geologists working in the earthworks(土方工程) created by the Panama Canal expansion project are finding. We think that a land bridge may have formed as early as 12 million years ago."

Not only does the age of the continental8 connection remain unresolved, there are more questions, such as what happened to the bees that used to be on the mainland and are no longer there now?

Panama's wealth of biodiversity may be a direct result of the complicated geological history of the area. Only by combining geological evidence, genetic evidence and observations of how organisms behave and respond to change in natural areas like Coiba National Park, can scientists begin to understand the puzzle that is Panama.



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1 descended guQzoy     
a.为...后裔的,出身于...的
参考例句:
  • A mood of melancholy descended on us. 一种悲伤的情绪袭上我们的心头。
  • The path descended the hill in a series of zigzags. 小路呈连续的之字形顺着山坡蜿蜒而下。
2 offshore FIux8     
adj.海面的,吹向海面的;adv.向海面
参考例句:
  • A big program of oil exploration has begun offshore.一个大规模的石油勘探计划正在近海展开。
  • A gentle current carried them slowly offshore.和缓的潮流慢慢地把他们带离了海岸。
3 glaciers e815ddf266946d55974cdc5579cbd89b     
冰河,冰川( glacier的名词复数 )
参考例句:
  • Glaciers gouged out valleys from the hills. 冰川把丘陵地带冲出一条条山谷。
  • It has ice and snow glaciers, rainforests and beautiful mountains. 既有冰川,又有雨林和秀丽的山峰。 来自英语晨读30分(高一)
4 ongoing 6RvzT     
adj.进行中的,前进的
参考例句:
  • The problem is ongoing.这个问题尚未解决。
  • The issues raised in the report relate directly to Age Concern's ongoing work in this area.报告中提出的问题与“关心老人”组织在这方面正在做的工作有直接的关系。
5 geologists 1261592151f6aa40819f7687883760a2     
地质学家,地质学者( geologist的名词复数 )
参考例句:
  • Geologists uncovered the hidden riches. 地质学家发现了地下的宝藏。
  • Geologists study the structure of the rocks. 地质学家研究岩石结构。
6 volcanic BLgzQ     
adj.火山的;象火山的;由火山引起的
参考例句:
  • There have been several volcanic eruptions this year.今年火山爆发了好几次。
  • Volcanic activity has created thermal springs and boiling mud pools.火山活动产生了温泉和沸腾的泥浆池。
7 genetic PgIxp     
adj.遗传的,遗传学的
参考例句:
  • It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
  • Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。
8 continental Zazyk     
adj.大陆的,大陆性的,欧洲大陆的
参考例句:
  • A continental climate is different from an insular one.大陆性气候不同于岛屿气候。
  • The most ancient parts of the continental crust are 4000 million years old.大陆地壳最古老的部分有40亿年历史。
TAG标签: species bees America
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