42 Hot and Cold Reptiles-High

Hot and Cold Reptiles FOCUS Question What determines whether some reptiles become male or female?

冷热爬行动物焦点问题是什么决定了一些爬行动物是雄性还是雌性?

A Girl or a Boy? Your dog is about to have puppies! Will she have girls or boys? The answer is in the cells. Dogs, like many other animals, carry information in chromosomes (CROW-ma-zohms) that determine whether their offspring will be female or male. The mother has two X chromosomes in her cells. The father has an X and a Y chromosome in his cells. Each offspring will get one of these chromosomes from each parent. If it gets an X from each parent, it will become a female (XX). If it gets an X from the mother and a Y from the father, it will become a male (XY). There is a 50 percent chance that the offspring will be male and a 50 percent chance it will be female.

女孩还是男孩?你的狗就要生小狗了!她会生男孩还是女孩? 答案就在细胞里。 像许多其他动物一样，狗在染色体(CROW-ma-zohms)中携带信息，决定它们的后代是男性还是女性。 母亲的细胞中有两条X染色体。 父亲的细胞中有X染色体和Y染色体。 每个后代将从父母双方各得到一条这样的染色体。 如果它从父母双方都得到X，它就会变成雌性(XX)。 如果它从母亲那里得到X，从父亲那里得到Y，它就会变成雄性(XY)。 后代有50%的几率是男性，50%的几率是女性。

Check the Temperature Not all animals use chromosomes to determine gender, though. Many reptiles rely on nest temperature instead! A mother reptile lays her eggs. Then there is a period of time when heat in the nest causes changes to the baby reptiles growing in the eggs. Eggs at lower temperatures make one gender. Eggs at higher temperatures usually make the other gender. A reptile will be male or female depending upon the amount of heat at its level in the nest.

然而，并不是所有的动物都用染色体来决定性别。 许多爬行动物依赖巢穴的温度!爬行动物妈妈产卵。 然后有一段时间，巢穴中的热量会导致在卵中生长的爬行动物宝宝发生变化。 温度较低的卵子只会形成一种性别。 温度较高的卵子通常会产生另一种性别。 爬行动物会是雄性还是雌性，这取决于它在巢中的热量水平。

Heat in the Nest Nest temperature can determine whether a baby will become male or female in three main ways: In some reptiles, lower-temperature nests produce females. Higher-temperature nests produce males. In other reptiles, nests with lower temperatures produce males, and nests with higher temperatures produce females. Certain reptiles produce females at both the lowest and highest nest temperatures. Males are only produced at the middle temperatures. Study the graph to explore a sample reptile species of each type.

巢穴的温度主要通过三种方式决定幼崽是男是女:在一些爬行动物中，温度较低的巢穴会生出雌性; 温度较高的巢穴产生雄性。 在其他爬行动物中，温度较低的巢穴产生雄性，温度较高的巢穴产生雌性。 某些爬行动物在最低和最高的巢穴温度下都能生育雌性。 雄性只在中等温度下产生。 研究图表以探索每种类型的爬行动物样本。

Cool Females, Warm Males Tuataras are often called living fossils because they show us what some animals were like long ago. Their closest relatives are an extinct group of reptiles that were alive when dinosaurs roamed Earth! They live in cooler places than most reptiles do. They are active at night instead of during the day. Nest temperature affects whether tuatara offspring will become male or female. At lower temperatures, the babies become females. At higher temperatures, they become males.

大鳄蜥通常被称为活化石，因为它们向我们展示了很久以前一些动物的样子。 它们最近的亲戚是一种已经灭绝的爬行动物，当恐龙在地球上漫游时，它们还活着!它们比大多数爬行动物生活在更凉爽的地方。 它们在夜间活动，而不是在白天。 巢的温度会影响大鳄后代是雄性还是雌性。 在较低的温度下，幼崽会变成雌性。 在更高的温度下，它们变成雄性。

Cool Males, Warm Females Red-eared sliders are a common type of turtle that live near ponds and lakes. The females build nests in soft, sandy soil in a sunny place near water. Nest temperatures affect turtle eggs in the opposite way from tuataras. If the whole nest is below 28°C, all the baby turtles will be males. If the eggs rest in nests at temperatures over 31°C, the baby turtles will all become females. At temperatures in between, about half the turtles will become male and half will become female. Math Moment At about what temperature will red-eared slider nests produce the most even mix of male and female turtles: 28.5°C, 29.5°C, or 30°C? Use the graph on page 4.

红耳龟是一种常见的龟类，生活在池塘和湖泊附近。 雌性在靠近水的阳光充足的柔软沙质土壤上筑巢。 巢穴温度对海龟蛋的影响与鳄蜥相反。 如果整个巢穴温度低于28°C，所有的小海龟都是雄性。 如果蛋在超过31°C的温度下休息，小海龟将全部变成雌性。 在两者之间的温度下，大约一半的海龟会变成雄性，一半会变成雌性。 大约在什么温度下，红耳滑块巢穴的雄性和雌性海龟的比例最均衡:28.5℃，29.5℃，还是30℃? 请用第4页的图表。