- 精华
- 301
- 积分
- 162885
- 经验
- 162885 点
- 威望
- 15221 点
- 金钱
- 43960 ¥
- 魅力
- 28358
|
2.1.4. 穴居动物的进化*(troglobites穴居动物!英文部分跟原文一样!)
一个主旨题,简单,就是说了一个理论,两个解释办法,最后作者提出了一点最近的研究成果做further explanation
我选的提出一个现象, 然后几个观点, 然后怎样怎样...
P1:介绍一种穴居动物Tih,传统的说法上说这个生物是怎么演化来的,说这种穴居动物一开始好像在什么潮湿的土地里,然后气候变化,剩下来的就是在洞穴里物种了。(后半段提到Hawai)
两个modeling解释为什么这种穴居动物会有这种进化规律
P2 modeling 1: pleistocene effect theory根据传统理论认为是climate造成。,因为温度改变. 穴居动物的祖先都是低温动物. 冰川过去, 温度上升, 穴居动物的祖先开始钻到森林最下面, 后来到山洞因为山洞里温度低,提到了潮湿木头等环境。举例:大概是某种昆虫P(两个细节体,其中一个和最后一个P打头的单词有关,那个单词快有20个字母了。。。实在想不起来)细节体都和我刚才说到的那个变态单词有关
一开始变冷,有些动物为了适应环境就慢慢住在离cave比较近的地方(大意),比较容易适应寒冷,也为他们之后住进cave里做准备。接下来天气更冷了,只有进化到住进洞里才不会冻死。那些适应的好的于是就成了穴居动物 stygobites。
P3 modeling 2 adaptive shift theory认为是适应原因(是一个合成词,含adapt)造成夏威夷的山洞那里是温度改变之后, 再慢慢地+食物因素继续进化. 也举了一人的研究成果为例。认为在这些地区没有p理论说到的那种突然的天气变化,因此是动物自己变的。
P4 作者:两种modeling都incomplete. 是说这两种理论都没有解释除了夏威夷(Hawai)以外的赤道地区的情况。因为赤道气候变化很小,所以这种动物基本在这个地方没怎么进化。现有的热带地区的温度都很稳定(没有温度的改变也就无法解释为什么会进化到洞里). 穴居动物少.但是最新的研究发现,赤道气候是变化的/但是最近发现了不少穴居动物而且热带地区的温度其实也是经历了变化的.否定观点1 “尽管climate变化,物种却没多少变化” 但是,又举了近期一研究,不是削弱2就是由肯定了1,我感觉最后仍然无法肯定哪派对。
1)如果赤道气候变化和这个物种的变化有很强的联系,那么以下哪个说法是对的
2)那个叫Barr得人应该会同意下面哪种观点。
3)有according to the last p, 问until recently, scientists认为....
热带地区的温度都很稳定 (MS正确)
没有什么穴居动物 (MS正确)
选项有点绕, 有一个表达肯定有问题. 我当时还觉得奇怪, until recently, 是什么意思? 应该是说以前是怎么认为的啊, 可是2个选项都正确??? 大家看清楚, 仔细推敲下.
4)还有一个according to the last p, 问如果热带地区的温度变化和进化有直接关联, 则哪个是正确的.
热带地区的山洞都是lime
热带地区有很多穴居动物
5)还有一题是问根据文章哪个是正确的 我选的穴居动物的祖先曾经在森林底下呆过.
背景:网上找了很久没找到原文。下面是比较接近的内容,大概说了一下两种理论。
Those highly specialized animals iliving entirely in the groundwater environment, and absent in surface waters, are called stygobites. 接下来说stygobites都有什么习性,包括哪些动物(记得有说蛇)。There are two main theories of cave colonization and troglobite evolution: 1. the pleistocene effect theory (Barr and Holsinger), 2. the adaptive shift theory (Howarth). The Pleistocene effect has been the most widely accepted model for the evolution of terrestrial troglobites until quite recently, During cold glacial climates, the cooler, wetter conditions south of the continental ice masses of Europe, Asia and America favoured the spread of invertebrates inhabiting both temperate forest ecosystems and caves. With the ameliorations of climate, those taxa that survived were those living in caves as the forest ecosystmes changed radically. Ultimately geographic and genetic isolation in these cave rerugia produced adaptive radiation and the evolution of distinct troglobites. In favor of this theory are the close affinities between closed forest and cave taxa, the present distributions of taxa in mountain areas separated by deep valleys, and former wider distributions evidenced from the fossil record.
The second theory, that of adaptive shift, was advanced by Howarth to explain the origin of troglobites in the Hawaiian lava tubes, but many have much wider applicability. This theory does not rely on climate change; rather it proposes that partially adapted ancestral species moved into cave niches almost continuously. These may have been species out-competed in surface environments. Thus the availability of food is the keystone of this theory, and troglobite evolution has been continual rather than episodic.这是关于第一种P理论的补充知识(没有在考试文章出现,不过对理解有帮助)The pioneering studies of cave life were predominantly carried out in the karst areas of Europe and North America, areas directly or closely associated with regions repeatedly covered by ice during the Pleistocene. Hence, the effects of glaciation came to dominate the debate about both the distribution and the origin of troglobitic animals. The classic view of the evolution of terrestrial troglobite is, in essence, that climatic instability in the surface environment - especially changes to cold and arid conditions associated with the onset and retreat of Pleistocene glaciations - led to the extinction of surface populations of species that mostly lived in forest soil and litter. This process disrupted interbreeding between the various troglophilic populations and permitted adaptation to the cave conditions in the now-isolated cave populations. |
|