睾丸在进化过程中起重要作用
文章来源:未知 文章作者:enread 发布时间:2016-06-16 08:21 字体: [ ]  进入论坛
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A pair of studies led by Indiana University researchers provide new evidence that when it comes to evolution, the testes may play a key role. The research, led by Kimberly Rosvall, assistant professor in the IU College of Arts and Sciences' Department of Biology, finds that the testes -- or gonads -- have a greater impact than previously1 thought in evolution. The research was conducted in two subspecies of dark-eyed junco, a type of American sparrow.
 
The white-winged junco, or Junco hyemalis aikeni, is found in the Black Hills of South Dakota. The slate-colored junco, or Junco hyemalis carolinensis, is from the Appalachian Mountains in Virginia. The first is larger and more aggressive; the other is smaller and more docile2.
 
The studies are published in the journals of Hormones4 and Behavior and of Integrative and Comparative Biology.
 
The first paper compares the subspecies in their expression of enzymes5 that make testosterone within the gonad. The second paper investigates how the subspecies' gonads differ in the expression of stress hormone3 receptor genes6, which are known to lower testosterone.
 
"The majority of endocrinologists will tell you that testosterone-mediated traits such as physical appearance or behavior are regulated in a top-down fashion -- that the brain acts as the 'CEO,' telling the rest of the body what to do," Rosvall said. "But our data suggest that this CEO model is oversimplified, and that the workers in the testosterone 'factory' -- the gonad -- may actually play an important role in trait divergence7."
 
Compared to the Virginia juncos, the South Dakota birds are not only larger and more aggressive, they also boast flashier plumage, including more white tail feathers and prominent white bars on their wings. All these traits are influenced by testosterone, which is widely recognized in biology to influence traits important in natural selection, such as survival and reproduction.
 
Within a population, some males produce more testosterone, others produce less. Over evolutionary8 time, average levels of testosterone -- and the traits that testosterone regulates, such as aggression9, body size, and even parental10 care or sex drive -- may evolve to suit a given environment. The genomic mechanisms11 that allow testosterone levels to evolve, however, are not well understood.


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1 previously bkzzzC     
adv.以前,先前(地)
参考例句:
  • The bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
  • Let me digress for a moment and explain what had happened previously.让我岔开一会儿,解释原先发生了什么。
2 docile s8lyp     
adj.驯服的,易控制的,容易教的
参考例句:
  • Circus monkeys are trained to be very docile and obedient.马戏团的猴子训练得服服贴贴的。
  • He is a docile and well-behaved child.他是个温顺且彬彬有礼的孩子。
3 hormone uyky3     
n.荷尔蒙,激素,内分泌
参考例句:
  • Hormone implants are used as growth boosters.激素植入物被用作生长辅助剂。
  • This hormone interacts closely with other hormones in the body.这种荷尔蒙与体內其他荷尔蒙紧密地相互作用。
4 hormones hormones     
n. 荷尔蒙,激素 名词hormone的复数形式
参考例句:
  • This hormone interacts closely with other hormones in the body. 这种荷尔蒙与体內其他荷尔蒙紧密地相互作用。
  • The adrenals produce a large per cent of a man's sex hormones. 肾上腺分泌人体的大部分性激素。
5 enzymes 7881ad8ce9c83424f7874e70266ed2d8     
n. 酶,酵素
参考例句:
  • It was said that washing powders containing enzymes remove stains more efficiently. 据说加酶洗衣粉除污更有效。
  • Among the enzymes which are particularly effective are pepsin, papain. 在酶当中特别有效的是胃朊酶、木瓜酶。
6 genes 01914f8eac35d7e14afa065217edd8c0     
n.基因( gene的名词复数 )
参考例句:
  • You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因,所以能够活得很长。 来自《简明英汉词典》
  • Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪
7 divergence kkazz     
n.分歧,岔开
参考例句:
  • There is no sure cure for this transatlantic divergence.没有什么灵丹妙药可以消除大西洋两岸的分歧。
  • In short,it was an age full of conflicts and divergence of values.总之,这一时期是矛盾与价值观分歧的时期。
8 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。
9 aggression WKjyF     
n.进攻,侵略,侵犯,侵害
参考例句:
  • So long as we are firmly united, we need fear no aggression.只要我们紧密地团结,就不必惧怕外来侵略。
  • Her view is that aggression is part of human nature.她认为攻击性是人类本性的一部份。
10 parental FL2xv     
adj.父母的;父的;母的
参考例句:
  • He encourages parental involvement in the running of school.他鼓励学生家长参与学校的管理。
  • Children always revolt against parental disciplines.孩子们总是反抗父母的管束。
11 mechanisms d0db71d70348ef1c49f05f59097917b8     
n.机械( mechanism的名词复数 );机械装置;[生物学] 机制;机械作用
参考例句:
  • The research will provide direct insight into molecular mechanisms. 这项研究将使人能够直接地了解分子的机理。 来自《简明英汉词典》
  • He explained how the two mechanisms worked. 他解释这两台机械装置是如何工作的。 来自《简明英汉词典》
TAG标签: evolution enzymes testes
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