[揽瓜阁精读] 301. 两种龙虾

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1

christinekaka

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Jiang233

1.介绍背景：The two claws different from each other.
   两种不同对比，对称比较人手
2.提出观点：Bilateral asymmetry of the claws comes about gradually.
   分论：a.观点发展的时间阶段；b.discovered by Victor Emmel:regenerate
3.深入观点：换爪的condition
   One possible explanation . This would explain why, 正向态度
4.证实观点：To test this hypothesis,
  做实验 一正一负

楓羽_

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sudn

同意！               

Asahii

301

楓羽_

卡

Fox的Dream

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Fox的Dream

301. 两种龙虾
P1 - The two claws of the lobsters are different. The crusher claw appears with equal probability on either the right /left side.
P2 - Bilateral asymmetry of the claws comes about gradually.
      In the juvenile 4/5 stages, the claws are symmetrical and cutterlike.
      In the 6th stage, the claws diverge towards cutter and crusher claws.
      VE: removing 1 claw, in the 4/5 stage, the intact one becomes a crusher and the regenerated one becomes a cutter.
            no changes in later stages.
P3 - These indicate the conditions that trigger differentiation operate in a random manner when the paired claws are intact, and in a non-random manner when one of claws is lost.
      One explanation: the differential use of the claws determines the asymmetry. The one used more becomes crusher.
P4 - To test the hypothesis, researchers raised lobsters in the 4/5 stages in a lab where the lobsters could manipulate oyster chips.=> the lobsters developed asymmetric claws.
      When the lobsters of the same stage were reared in a smooth tank w/o the oyster chips, the majority developed two cutter claws. And this unusual configuration of symmetrical claws did not change.

sudn

一共四段，提出一个现象：
龙虾两只钳子长得不一样： crusher vs cutter， 和多数人是右撇子不一样，龙虾这两个不一样的钳子，左右分布几率大致相当。

不对称钳子的形成过程：在生长中逐渐形成。青年4-5阶段，还是一样的。 进入青年6阶段，不对称就显现了。VE发现4-5阶段如果搞掉一只钳子，留下来哪只会变成crusher，新长出来的钳子变成cutter。6阶段及之后搞掉一只钳子，钳子会再长出来，然而不会改变特征了，掉啥长啥。因为掉之前已经成型了，确认了这是个crusher or cutter。

试图解释这个现象：两个钳子都完整的时候，是随机长的， 如果丢了一个，就不随机了。
cusher 和cutter 的不同功能决定了他们长得不一样。比如cusher 可能用的更多。也就解释了为啥4-5阶段丢了一只的话，剩下一只无论如何都会变成cusher。即使两只都完整，4-5阶段龙虾会用其中一只更多，这只就慢慢变成cusher。

搞个实验来验证上面的猜测：模拟海洋环境中有oyster chips 4-5 阶段的龙虾的钳子就长得不对称，左右 右左分布一半一半。 水箱里 没有oyster 的环境中，大部分都长了两个cutter。这个特征不会改变了，不管是换个海洋环境还是搞掉1-2 个钳子。