2014.5.25
(1)人类的活动和动物的灭绝
将overhunting，中间一个个科学家说不对，其实是climate change导致了，讲人类人前北美很多大型动物，但是人类出现以后大型动物都挂了，主要原因是人类的过度捕猎。接着说气候也是一个潜在原因，而且一些大型动物挂了，认识rodent并没有灭绝。有举例，在人类出现以后很短的时间内动物数量急剧下降，虽然这个事实被捕鱼大丰收的情况所disguise，一个明显的证据就是一种特殊的鱼到了食物链底端。
解析：本篇文章讲解了动物的灭绝的原因。相似的话题可以参考tpo中文章mass extiction，文章的理解重点是要把握好解释灭绝的原因，以及相对应所举的例子。按照不同的灭绝的原因梳理文章的结构。相应的背景请参考下文：
As long as species have been evolving, species have been going extinct. It is estimated that over 99.9% of all species that ever lived are extinct. The average life-span of a species is 10 million years[citation needed], although this varies widely between taxa. There are a variety of causes that can contribute directly or indirectly to the extinction of a species or group of species. "Just as each species is unique", write Beverly and Stephen C. Stearns, "so is each extinction ... the causes for each are varied—some subtle and complex, others obvious and simple". Most simply, any species that cannot survive and reproduce in its environment and cannot move to a new environment where it can do so, dies out and becomes extinct. Extinction of a species may come suddenly when an otherwise healthy species is wiped out completely, as when toxic pollution renders its entire habitat unliveable; or may occur gradually over thousands or millions of years, such as when a species gradually loses out in competition for food to better adapted competitors. Extinction may occur a long time after the events that set it in motion, a phenomenon known as extinction debt.
Habitat degradation
Habitat degradation is currently the main anthropogenic cause of species extinctions. The main cause of habitat degradation worldwide is agriculture, with urban sprawl, logging, mining and some fishing practices close behind. The degradation of a species' habitat may alter the fitness landscape to such an extent that the species is no longer able to survive and becomes extinct. This may occur by direct effects, such as the environment becoming toxic, or indirectly, by limiting a species' ability to compete effectively for diminished resources or against new competitor species.
Habitat degradation through toxicity can kill off a species very rapidly, by killing all living members through contamination or sterilizing them. It can also occur over longer periods at lower toxicity levels by affecting life span, reproductive capacity, or competitiveness.
Habitat degradation can also take the form of a physical destruction of niche habitats. The widespread destruction of tropical rainforests and replacement with open pastureland is widely cited as an example of this; elimination of the dense forest eliminated the infrastructure needed by many species to survive. For example, a fern that depends on dense shade for protection from direct sunlight can no longer survive without forest to shelter it. Another example is the destruction of ocean floors by bottom trawling.
Diminished resources or introduction of new competitor species also often accompany habitat degradation. Global warming has allowed some species to expand their range, bringing unwelcome competition to other species that previously occupied that area. Sometimes these new competitors are predators and directly affect prey species, while at other times they may merely outcompete vulnerable species for limited resources. Vital resources including water and food can also be limited during habitat degradation, leading to extinction.
Predation, competition, and disease
In the natural course of events, species become extinct for a number of reasons, including but not limited to: extinction of a necessary host, prey or pollinator, inter-species competition, inability to deal with evolving diseases and changing environmental conditions (particularly sudden changes) which can act to introduce novel predators, or to remove prey. Recently in geological time, humans have become an additional cause of extinction (many people would say premature extinction) of some species, either as a new mega-predator or by transporting animals and plants from one part of the world to another. Such introductions have been occurring for thousands of years, sometimes intentionally (e.g. livestock released by sailors on islands as a future source of food) and sometimes accidentally (e.g. rats escaping from boats). In most cases, the introductions are unsuccessful, but when an invasive alien species does become established, the consequences can be catastrophic. Invasive alien species can affect native species directly by eating them, competing with them, and introducing pathogens or parasites that sicken or kill them; or indirectly by destroying or degrading their habitat. Human populations may themselves act as invasive predators. According to the "overkill hypothesis", the swift extinction of the megafauna in areas such as Australia (40,000 years before present), North and South America (12,000 years before present), Madagascar, Hawaii (300-1000 CE), and New Zealand (1300-1500 CE), resulted from the sudden introduction of human beings to environments full of animals that had never seen them before, and were therefore completely unadapted to their predation techniques.
Climate change
Extinction as a result of climate change has been confirmed by fossil studies. Particularly, the extinction of amphibians during the Carboniferous Rainforest Collapse, 305 million years ago. A 2003 review across 14 biodiversity research centers predicted that, because of climate change, 15–37% of land species would be "committed to extinction" by 2050. The ecologically rich areas that would potentially suffer the heaviest losses include the Cape Floristic Region, and the Caribbean Basin. These areas might see a doubling of present carbon dioxide levels and rising temperatures that could eliminate 56,000 plant and 3,700 animal species.
(2) 讲得是pest的问题，如何处理害虫。。
先讲了一个例子好像是美国西南部，具体记不清了，其实是为了引出 chemical 方法 ，就是杀虫剂pesticide，而且还讲了杀虫剂的负作用，会对native的一些物种造成预想不到的损伤。同时pest产生耐药性的时间大约5年，远短于研制出新的pesticide所需要的时间。(就是说这方法有明显缺陷，好引出下面的方法，你们懂得!!!肯定有题的嘛...)
然后就讲了biological方法，引进pest的天敌，因为多数顽固的pest其实是外来物种，之所以成为pest就是没有天敌。这里举了中国古代的一个例子，知道例子的功能就好。 (有题)然后这提到了一些不足，细节记不太清楚了。
最后来到了终极大招，一个叫IPM的方法让害虫们明白!!!其实就是一种integrated的什么方法，综合考虑各种因素，什么经济啊，生物学啊，如果不得不用杀虫剂要控制剂量啊等等(有排除题)。其实我觉得不算新方法，但是就是综合考虑，然后就有了IPM这样一个酷炫的名字。
解析：本篇文章讲解了处理害虫的不同方法。理解文章时按照不同的处理方法梳理文章的结构，不同的方法要把握住作者关于其优点和缺点的介绍，不同的方法的不同特点为文章出题的题点。
Insects become resistant to chemical insecticides very rapidly—it can happen in as few as five generations. This is natural selection at work.
The problem is that an insecticide never kills all of its intended victims. If even a few insects survive, they will reproduce. These surviving insects will produce two types of young—those that are resistant to the spray, and those that are not. The non-resistant insects will be killed in the next spraying, but those that are left reproduce. At each generation, the number of naturally resistant insects in the population increases.
An individual insect does not become resistant during its lifetime. It is born either resistant or non-resistant, and it is the population as a whole that gradually becomes resistant to the pesticide over time. The Bt toxins become ineffective, and the benefits of using them (less toxicity to non-target species) disappear.
As this occurs, a new pesticide must be developed. Over time, populations of insects can become resistant to more and more pesticides. As a result, humans need to make different pesticides that are generally stronger.
Organic farmers have used Bt on their crops for a number of years. They are concerned that the increased use of the Bt toxin could speed up the development of resistant insect populations.
Entomologists know that controlled, laboratory experiments with generations of insects cannot be easily reproduced in the field. How the resistant insects breed with refuge insects, and over what time frames, will determine the success of this technology.
These concerns are balanced by concerns that existing pesticide practices can be much more dangerous for non-target insect species than insect-resistant crops. Conventional non-selective pesticides kill many non-target insects. By reducing the number of sprays needed, insect-resistant crops help to preserve beneficial predator insects and simplify management decisions.
(3) 讲的是动物、昆虫的发声的问题
最开始怎么说的记不清楚了，第一层应该就是rain forest里面的小东东怎么让声音传播。热带雨林里面这么吵，要让同类听到自己还是很不容易的，尤其对于那些小昆虫什么的，而且很多小东西通过发声来求偶交配嘛，你们都懂的!!!Rain forest这里举了一个树蛙的例子，就是这小青蛙用的一种招数，它一般会进到有水的树洞， 身体一部分没入水中，然后开始发声，找到与大树能共鸣的频率，这不就能传的更高更远嘛。(有排除题)
下面一层应该是讲birds，同时提到了它们叫的时间一般是在早上和黄昏，那个时候声音能传得更远， 但是有些时候也会让天敌们发现之类的(没记错的话，最少有俩道题)
最后一层应该是提到了不同物种的发声频率不同，这能让它们被分辨出来。还有一个教授，把声音录下来回去分析，发现每个雨林的声音还不太一样，也是unique的，甚至可以像人类的指纹一样去分辨树林的独特声音什么的(有题)
解析：本篇文章讲解了雨林中不同动物不同的传递信息的方式。属于生物学中典型的话题，请大家理解文章时重点关注生物传递信息的方式与雨林环境的适应性的体现。相应背景请参考下文：
The daytime quality of light in forests varies with the density of the vegetation, the angle of the Sun, and the amount of cloud in the sky. Both animals and plants have different appearances in these various lighting conditions. A color or pattern that is relatively indistinct in one kind of light may be quite conspicuous in another.
In the varied and constantly changing light environment of the forest, an animal must be able to send visual signals to members of its own species and at the same time avoid being detected by predators. An animal can hide from predators by choosing the light environment in which its pattern is least visible. This may require moving to different parts of the forest at different times of the day or under different weather conditions, or it may be achieved by changing color according to the changing light conditions. Many species of amphibians (frogs and toads) and reptiles (lizards and snakes) are able to change their color patterns to camouflage themselves. Some also signal by changing color. The chameleon lizard has the most striking ability to do this. Some chameleon species can change from a rather dull appearance to a full riot of carnival colors in seconds. By this means, they signal their level of aggression or readiness to mate.
Other species take into account the changing conditions of light by performing their visual displays only when the light is favorable. A male bird of paradise may put himself in the limelight by displaying his spectacular plumage in the best stage setting to attract a female. Certain butterflies move into spots of sunlight that have penetrated to the forest floor and display by opening and closing their beautifully patterned wings in the bright spotlights. They also compete with each other for the best spot of sunlight.
Very little light filters through the canopy of leaves and branches in a rain forest to reach ground level—or close to the ground—and at those levels the yellow-to-green wavelength predominate. A signal might be most easily seen if it is maximally bright. In the green-to-yellow lighting conditions of the lowest levels of the forest, yellow and green would be the brightest colors, but when an animal is signaling, these colors would not be very visible if the animal was sitting in an area with a yellowish or greenish background. The best signal depends not only on its brightness but also on how well it contrasts with the background against which it must be seen. In this part of the rain forest, therefore, red and orange are the best colors for signaling, and they are the colors used in signals by the ground-walking Australian brush turkey. This species, which lives in the rain forests and scrublands of the east coast of Australia, has a brown-to-black plumage with bare, bright-red skin on the head and a neck collar of orange-yellow loosely hanging skin. During courtship and aggressive displays, the turkey enlarges its colored neck collar by inflating sacs in the neck region and then flings about a pendulous part of the colored signaling apparatus as it utters calls designed to attract or repel. This impressive display is clearly visible in the light spectrum illuminating the forest floor.
Less colorful birds and animals that inhabit the rain forest tend to rely on forms of signaling other than the visual, particularly over long distances. The piercing cries of the rhinoceros hornbill characterize the Southeast Asian rain forest, as do the unmistakable calls of the gibbons. In densely wooded environments, sound is the best means of communication over distance because in comparison with light, it travels with little impediment from trees and other vegetation. In forests, visual signals can be seen only at short distances, where they are not obstructed by trees. The male riflebird exploits both of these modes of signaling simultaneously in his courtship display. The sounds made as each wing is opened carry extremely well over distance and advertise his presence widely. The ritualized visual display communicates in close quarters when a female has approached.