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NARRATOR:Listen to part of a lecture in a biology class.
FEMALE PROFESSOR:For today's discussion, we'll review the case study on how some animals have behaviorally adapted to their environments.Now you had to read about two animal species,:the Eastern marmot and the Olympic marmot.Marmots are rodents... they're large ground squirrels about the size of an average house cat, and they live in a variety of habitats.And even though they spend the significant portion of the year hibernating, according to this case study, marmots are still considered excellent subjects for animal behavioral studies. Why is that?
MALE STUDENT:Well, when they're not hibernating, you can find them in open areas, and they're pretty active during the day, which makes them easy to observe, right? [rising tone]
FEMALE PROFESSOR:[encouraging tone] Unh huh. So, first let's discuss the eastern marmots.They reside throughout the eastern region of North America where there's a temperate climate, where the growing season lasts for at least five months of the year... which is when they do all their mating, playing, and eating.
MALE STUDENT:Oh, I see... at first, I wasn't sure what 'growing season' meant just from the reading, but now I get it.It's the amount of time it takes for them to grow, right? [rising tone]So it would be five months?
FEMALE PROFESSOR:Hm? Ohh, I'm sorry but no, It has nothing to do with that.It's not about the time it takes for Eastern marmots to grow,It's when the food is available.That is--when it’s not covered in snow and there's no frost covering the grass, and um vegetative parts of uh, plants, herbs, and the flowers that marmots like to eat.So, 'growing season' refers to the availability of the food they eat. Ok?So now how would you describe the Eastern marmots'social habits?
FEMALE STUDENT:Well, they are really territorial, and loners, and just so aggressive even with other Eastern marmots.And their mating ritual is just so... impersonal.
FEMALE PROFESSOR:[agreement] Uh huh.Now when they emerge in the spring from hibernation, the mating process begins. For them, well, they come together to mate and then they go their separate ways.Then about six to eight weeks after birth, the offspring leave their mothers.
FEMALE STUDENT:Really? Just six weeks?Is it possible for the offspring to make it on their own so young? [concerned]
FEMALE PROFESSOR:Well, it's not as if they aren't ready for the real world because they are.Remember, they mature quickly and the weather's nice. Also they live in open fields where there is lots of edible vegetation. So roughly six weeks after birth, eastern marmots are just old enough to take their chances of surviving in a temperate environment. [pause]So how does this relate to their behavior?
FEMALE STUDENT:Oh, I get it.Since the climate's not too bad, the Eastern marmots don't have to rely on each other too much and they really don't need to stay together as a family to survive either.
FEMALE PROFESSOR:Uh huh. And in contrast... the Olympic marmots... what about them?
FEMALE STUDENT:Well, they live together as a family and take care of their young until they are at least two years old.They're really friendly with each other, and what I really like is that they even have greeting ceremonies and they're not at all aggressive and territorial like the eastern marmots.So their social behavior is so different from Eastern marmots because of the climate where they live? That seems so bizarre.
FEMALE PROFESSOR:Well, the Olympic marmots inhabit meadows high in the Olympic Mountains where the weather conditions are much harsher so there is a lot more wind and snow.The growing season only lasts about two to three months. So in that much shorter period of time, all the Olympic marmots, male and female, eat, play, work and nurture the young together. Because the climate is so harsh, cooperation increases the survival rate of the Olympic marmots. They keep their young at home until they are physically able to survive on their own.This could explain why the social behavior of the Olympic marmots is so unlike that of the Eastern marmots.
旁白：听生物课的部分讲座。
教授：在开始今天的讨论前，我们先回顾一下动物是如何在行为上适应他们环境的案例研究。现在大家来了解一下这两类动物：东部土拨鼠的和奥林匹克山土拔鼠。土拔鼠属于啮齿动物，它们是大型的地松鼠，体形有一般家猫那样大，它们栖息在不同的地方。即便据案例研究的材料显示，虽然它们花相当多的时间冬眠，土拔鼠仍然被视为动物行为研究的绝佳对象。为什么会这样呢？
是这样的，在非冬眠时期，你会在空旷地区看到它们。它们白天很活跃，这样发现它们就不是难事了，对吧？
啊哈，我们首先讨论一下东部的土拔鼠。它们的“住所”遍布北美东部地区，这里气候温和，全年有五个月以上的生长期，在这段时间里它们会进行交配，玩耍和觅食。
哦，了解。一开始仅凭阅读材料我并不知道生长期是什么意思，但我现在知道了。是它们用来生长的一段时间，对吧？那就应该是五个月吧？
嗯？哦，呃…恐怕不是的，跟这个没有关系。不是跟东部土拔鼠用在生长的时间有关，而是跟什么时候有食物有关。那时，地上没有冰雪覆盖，草木也没有结霜，嗯，土拔鼠喜欢吃的植物嫩芽和花蕾开始生长。所以，生长期指的是它们所吃食物的可获得性，是不是？那么，你们如何描述东部土拔鼠的社会习性？
它们的区域所属感很强，而且独来独往，同时即便是与同类相处也表现出非常强的侵略性。还有，它们用情并不专一。
啊哈？春天，当它们从冬眠中醒来出来活动时，交配过程就开始了。它们聚到一块交配，随后各奔东西。产仔后的六到八周，小土拔鼠们离开鼠妈妈。
不会吧？就六周？鼠宝宝那么小能独自存活吗？
并不是因为它们太小而不能适应现实世界。记住，它们成熟很快，而且天气也不错。此外，它们住在盛产可食植被的空旷地区。所以，大概出生后六周，东部土拔鼠能长到足以在这温暖的环境中生存。那么，这又跟它们的行为有什么关系呢？
哦，我明白了。因为气候还不错，东部土拔鼠没必要过于相互依赖，也没有必要以家庭为单位而存在。
啊哈。对比起来，那些奥利匹斯山土拔鼠呢？
它们以家庭为单位过着群居生活，同时照顾幼鼠直到它们长到两岁。它们之间关系融洽，我很看好的一点是它们见面还有招呼“礼节”，此外，它们一点都不好斗，地域所属感也不强，这两点跟东部土拔鼠是大相径庭的。难道气候造成了它们迥异的社会习性？这种看法很是荒谬。
事实上，奥林匹斯松土拔鼠栖息的草地在奥林匹克山脉的高地，那里的气候条件要恶劣得多，风雪也比东部多。生长期只持续两到三月。在那相对短得多的时间里，所有的奥林匹斯松土拔鼠，不分雄雌，觅食，玩耍，劳作和养育幼鼠。因为气候恶劣，协作能提高奥林匹斯松土拔鼠的存活率。它们抚育幼鼠直到幼鼠能自食其力。这能解释为什么奥林匹斯松土拔鼠的社会习性和东部土拔鼠的（社会习性）如此不同。
题型分析：主旨题
原文定位：
For today’s discussion, we’ll review the case study on how some animals have behaviorally adapted to their environments. Now, you had to read about two animal species:
the eastern marmot and the Olympic marmot.
选项分析：
开头讲到今天要说两种marmots，并且要说他们是怎样behaviorally adapted to their environments，后文确实分别讲到了两种marmots，并且说了他们所处环境不同，导致行为不同，本题答案选D。错误选项可以试着会原文对应一下：A选项中的types of habitats未提到。
B选项，文章有observe的字样，但并不是在讲methods of observing。C选项，饮食习惯是细节。
如果对题目有疑问，欢迎来提出你的问题，热心的小伙伴会帮你解答。