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- 2013-8-3
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- 1970-1-1
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The researcher finds that the saliva of animals that eat toxic plants can keep these animals from being poisoned. For example, red fescue can produce a toxin, which can cause animals to lose limbs. However, when saliva of reindeer and moose is dribbled over the plants, the production of such saliva reduce. So, the researchers conclude that saliva has more use than we know.
time2
In the beginning, the author simply introduces the term "mutualism". Mutualism is a relationship that two different species keep to benefit each other, including co-operation and interspecific competition. Then, the author gives us an example to further illustrate the concept.
3m5s
Second, the author tells us that mutualism is very important in the nature. It helps ecosystem function well and also drives the evolution of much of the biological diversity.
However, how to define the mutualism is a problem. At present, the researchers measures the closeness of two species to categorize mutualism, but this measurement can refer to mutual dependency or physical closeness.
time3+4
The acacia trees will suffer because of a type of ant if no herbivores don't eat them anymore. The researchers conduct a experiment to prove that. They find that without large herbivores, these trees will excret the sweet nectar in order to attract their bodyguard ants. However, this sweet nectar will induce another type of ant, and the ant can accelerate the activity of beetles, which stunts the growth of trees and causes them to die.
Even though the result only apply to this kind of tree, it also provides an example of how the disappearance of large herbivores can have unexpected consequences.
3m37s
5+6time
Recently, researchers find that we can boost plant growth and crop yields by using fungi, bacteria and viruses rather than genetical method. Then, the author mentions a lot of examples to prove this view of point: microbial useful to capture nitrogen can reduce the need for chemical fertilizer, fungi taken from hot spots can increase the heat resistence of tomatoes, and microbes from polluted places can help plants to resist heavy metals.
However, such useful fungi also have drawbacks. The author mentions that the alkaloid can cause a disease to grazing cattles.
3m54s
Obstacle
It is surprising that spiders feed on plants. Recently, the researchers have found that a jumping spider eats mostly plants, named acacia plants, and interfere a co-operation between these plants and ants. Like vegetarian spider, the jumping spider doesn't eat ants but leaves of the plants. It also feeds on nectar and ant larva.
The researchers also try to discover what helps the spider digest plants material, which most consists of fiber, figure out the relationship between the jumping spider and its neighbor spiders, and understand why the spider-plant-ant system can stabilize.
7m6s |
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