28、**达尔文理论 [版本1] by choclee 710 达尔文的理论，雌性动物要养孩子，一般男性动物主动来找女朋友，举个例子和达尔文的观点不太一样，貌似是雌性动物有时候更主动。第二段开始解释。开始先说了一个人都研究，后来又说了T和A的研究，有考题，T和A俩人的观点。这里雌性动物主动找雄性动物，雄性可以提供食物，发信号，有一点是雌性找到雄性的时候雄性可以给雌性一个有价值的神马东西，最后总结可以得出什么结论和不可以证明什么。
[版本2] by sawayisa 什么雌性的虫子神马的，后来两个任研究。最后没时间了，基本没看。
[版本3] by lixiaの畅 有关昆虫的，什么雄虫要是想通过气味什么的吸引伴侣就要给伴侣点好处。。什么的 和达尔文的进化论也有点关系
[版本4] by zj_stpaul 760，Q51+V42 2.我的最后一篇，读的很快，可能不准，大家悠着点。第一段讲动物中大部分都是female看家还是养孩子什么的，risk很小，而male在寻偶的过程 中承担了很大的风险。第二段说，某些species中这种现象反过来了，是male在某个点候着，吸引female过来，通过发送什么signal。发送 的那个signale在吸引female过来的同时，也给female提供了something of value，比如告诉她们我这里有食物啊，或者能给你一些什么东西，保护你不受predation啊，等等。
Signals used to attract mates are often conspicuous to predators and parasites, and their evolution via sexual selection is expected to be opposed by viability selection. Many secondary sexual traits may represent a compromise between attractiveness and avoidance of detection. Although such signal exploitation appears to be widespread, most examples come from species that use acoustic or olfactory mating signals, and relatively few cases of visual signal exploitation can be substantiated. Because males are usually the signaling sex, they are more at risk from predators or parasitoids that locate prey or hosts by sexual signals; this differential selection on the two sexes can affect the intensity of sexual selection on male ornamental traits. The notable exception to male signaling and female attraction occurs in pheromone-producing insects, particularly lepidopterans, which show an opposite pattern of female odor production. Exploitation of such sex pheromones is relatively rare. We discuss reasons for the reversal in sex roles in these species and its implications for signal exploitation. Changes in signals that appear to be adaptations to avoid predation include the use of different signal modalities, changes in signaling behavior, loss of signals, and alteration of signal characteristics such as pitch. Selection pressure from signal exploiters could lead to the production of a novel signal and thus facilitate speciation. Relatively little work has been done on adaptations on the part of the exploiting species, but such adaptations could indirectly influence the mating system of the predator or parasitoid. Signal exploitation is also expeded to be a fruitful source of examples of coevolution. Finally, plants emit attradants analogous to secondary sex characters in animals, and may also be vulnerable to signal exploitation.
.durable产品的price variation，LZ之前在寂静里看到过，第一段讲人们虽然生成买耐用品时产品是重要决定因素，但事实上很少花很长时间调查市场或在不同卖场之间比较价格，耐用品的价格variation很大||第二段讲对这一现象的两种理论解释，第一种theory是消费者的关于耐用品expect of savings from comparison小于实际，第二种theory是消费者对价格地的商品的比价反而高于耐用品，举例是对于100元的产品和400元的产品，消费者会花更多的时间在100元的产品的比价上来寻求与400元产品同样的减价额度。 有一题是问下列哪个fact会削弱第二种理论。 （by imayday2012）
P2：为什么明知道店与店之间价差大，消费者的价格敏感度还是这么低，不会去比价呢？a possible explanation…,expect of savings from comparison less than actual savings。第二个解释是某人提出的某个theory，举例说100元和400元的商品，都减价20，但是消费者会对本来100元的商品进行比价，400元就不必了，因为relative saving的关系。 Q2：主旨题，选phenomenon and explain
请楼主确定作文： The country of Bonaria held a major soccer event five years ago. Therefore, if the country continues to hold major sport events, tourism will increase rapidly in the country and thus bring benefits to the country's economy.
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发表于 2012-12-7 04:55:44
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