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2019年09月17日 04:32:35    日报  参与评论()人

嘉兴有哪些整形医疗机构嘉兴做双眼皮好的医院Depending on the species, bird eggs can be any color rangingfrom chickens plain white to a robins blue, streaked, spotted,bright, pale, and anything in between.不同鸟类蛋壳的颜色千差万别,鸡蛋是纯白色,知更鸟蛋是蓝色,其它蛋壳的颜色迥异:有条纹的、有斑点的、亮色的、淡色的或者是介于之间的。We take a look at someof the reasons this might be the case.那么,让我们看看颜色不一的原因吧!But first, how do eggs get their color?那么,蛋壳的颜色是如何形成的呢?As the egg moves downthe females oviduct, the tube that connects the ovary to the outside, it squeezes against glands that produce colored pigments that combine to form every color in the egg shell spectrum.鸟蛋经由母体的输卵管排出,分泌色素的腺体受挤压,给蛋壳着色。If the egg is stationary at the time that it comes in contact with these glands, itll bespotted.如果此刻鸟蛋是静止的,触碰腺体的蛋壳形成斑点; If the egg is in motion, it will be streaked.如果是运动的,蛋壳形成条纹。So why go through all the trouble of producing colored eggs?为什么那么大费周章地形成不同色呢?For many species of birds that nestout in the open, the eggs colors help to conceal them by enabling them to blend into the back ground.一些鸟类的巢在露天野外,蛋壳的色有助于和外界混为一体,便于隐藏。Another way that colored eggs come in handy, is that in some species, like murres,individual birds learn to recognize their own particular markings and reject eggs that dont match.蛋壳颜色还在某些地方能排上用场:例如海鸦,通过蛋壳颜色来识别,排除它类。In contrast, birds that nest in cavities, or that start incubating as soon as the egg is laid andconsequently dont need to hide their eggs, tend to lay unmarked white ones.另外一些鸟类在树洞中筑巢的,或下蛋后马上孵化的;鸟蛋不用隐藏,蛋壳颜色通常是白色。Given all this, how do scientists explain the fact that robins eggs are an eye-catching, unmarkedblue?终上所述,科学家如何解释知更鸟蛋是耀眼的纯蓝色呢?Perhaps this enables robins to spot when a parasitic bird tries to add its own eggs to the nest.也许这样便于知更鸟识破其巢寄生的鸟类将自己蛋放进知更鸟巢吧!For some species, this may pose a greater threat than that of nest robbers.巢寄生的行为对其他鸟类更具威胁性! 201409/325605浙江嘉兴腋臭哪家医院治疗好 平湖做双眼皮埋线多少钱

嘉兴手术去除口周纹嘉兴去除鱼尾纹 嘉兴曙光整形医院丰唇好不好

嘉兴市第二医院做隆鼻手术多少钱 Whats the matter,don?You look worried.你怎么了唐,看起来有些着急。You know how people are always predicting that one day women will be able to have babies without men?你是否曾听说过某一天女性将不需要男性也可生小孩?It turns out that some species of the Whiptail lizard have figured out how to do this and completely eliminated the male sex.事实上一些种类的长尾蜥蜴已经可以做到这一点,并将全部的雄性完全消灭掉了。You mean the species are all female?Exactly.你的意思是物种全部是雌性?的确是这样。The females have the ability to lay eggs that hatch and grow into healthy lizards without needing to be fertilized by a male.无须借助雄性受,雌性蜥蜴有能力产下可以孵化出健康的小蜥蜴的蛋。The offspring are exact and complete genetic duplicates of the mothers.其后代完全是母亲们基因的复制品。So the females are clonnig themselves.这在本质上是雌性在克隆自己。If that werent enough, the female lizards take turns role-playing.如果这还不够的话,雌性蜥蜴会轮流扮演角色。They perform a mating ritual in which one lizard acts like the male, and the second lizard acts like the female.她们在交配过程中,一只扮演雄性,另一只扮演雌性。The ritual causes the lizard acting as the female to ovulate and lay her eggs.交配将使扮演雌性的蜥蜴排卵产蛋。Then, a few weeks later, the two lizards switch roles and repeat this process so that the second female will be able to ovulate and lay her eggs.几周之后,两只蜥蜴互换角色重复交配过程从而使得另一只雌性得以排卵。It raises a lot of interesting questions.这引发了许多有意思的问题。For example, its not clear how well an all female species can evolve and adapt to environmental changes.例如,我们尚不清楚一个完全由雌性组成的种群在面临环境变化是能否很好地适应和进化。A species survival depends in part on variation among its members.一个种群的存在,部分地取决于其内部成员的多样性。If all the members of a species are identical, chances are greater that something like a change in the climate or a disease will wipe them all out.如果一个种群中所有的成员具有同一性,那么当环境剧变或疾病肆虐时,它们的灭绝概率也将更大。 /201309/256998平湖市第一人民医院做韩式隆鼻手术多少钱海宁市第四人民医院割双眼皮多少钱



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