越读--Seabutterfly全文考古题--高度类似！ - ChaseDream

The nature of this relationship is puzzling. It is difficult to discern how carrying another organism around can be advantageous.We speculated that in fact, amphipods must be considerably slowed down. By carefully measuring the swimming speeds of amphipods with and without sea butterflies, we found that amphipods carrying sea butterflies moved only half as quickly as similarly sized solitary amphipods. The situation simply made nosense. In reducing their mobility, the amphipods became more vulnerable topredators and less adept at capturing prey. Why, then, would amphipods go out of their way to abduct and carry sea butterflies?

Our experiments clearly demonstrated that something about the sea butterflies was repelling the fish, and we suspected that this deterrence was chemical. To find out, we conducted a second set of feeding experiments. We homogenized the sea butterflies and mixed the homogenate with fish-meal powder to make food pellets. As a control, we also made food pellets containing just the fish-meal powder. We offered both the experimental and the control pellets to fish, which always ate the control pellets and always rejected the pellets containing the homogenate. This provided compelling evidence that compounds might be responsible for the feeding chemical deterrence.

Our experiments demonstrated to us that the sea butterfly C. antarctica synthesizes a deterrent substance that the amphipod H. Dilatata exploits for its own protection. This unique association - the abduction of one species by another - is unprecedented in the annals of behavioral and chemical ecology. Some decorator crabs are chemical ecology known to cover their upper carapace with a variety of objects, including the occasional sponge that might harbor defensive chemistry. But this appears to be a non selective behavior. Crabs haphazardly decorate themselves with whatever is at hand.

The association between the sea butterfly and the amphipod falls within the definition of symbiosis共生, where two dissimilar species live together in an intimate association. However, none of the relationships defined within the broad context of symbiosis - parasitism, comensalism or mutualism -appear to suitably describe the sea butterfly-amphipod relationship.

Parasitism寄生 implies that one species associates with another to the detriment伤害of one of them. Often, the parasite feeds off the tissues or body fluids of its host. Mutualism共生describes a relationship where both species benefit from the association. Commensalism describes organisms that live in benign and neutral中立or良性association with one another. Neither of the latter two interactions appropriately describes what we have observed, and parasitism provides only a very weak analogy to it. We feel that a new term might be needed to describe the "antagonistic symbiosis" that seems to describe most accurately this unique interaction.

寄生:一个伤害另一个，吃对方组织和体液。共生:双方都获利。commensalism共栖:中立，互相不干扰。实际(如果加上下一段的文章):一个获利，另一个间接受害,若没有下面这段,得看选项怎么说了.网上的定义是the association is disadvantageous or destructive to one of the organisms, but ordinarily it is used of cases where the association is advantageous, or often necessary, to one or both, and not harmful to either.

In this association the antagonist benefits greatly from the relationship. Remember that the amphipod must sacrifice its mobility and speed. Clearly the defense it acquires offsets these drawbacks. The sea butterfly, on the other hand, is at the mercy of the amphipod. While it is being carried around, it cannot feed to sustain its energy."