This, however, turns out not to be the case. In experiments, vacancies have been contrived by removing an established fish from a community. Elimination of the breeding male triggers the prompt maturation of the largest juvenile. Each remaining juvenile also grows somewhat, and a minuscule newcomer drops in from the plankton. Removal of the female also triggers growth in all remaining fish and acceptance of a newcomer, but the female is replaced by the adult male. Within days, the males behavior alters and physiological transformation is complete within a few months. Thus, whichever of the breeding pair is lost, a relatively large juvenile can fill the void, and reproduction can resume with a minimal loss of time. Furthermore, the new mate has already proved its ability to survive.
This transformation of a male into a female, or protandrous hermaphroditism, is rare among reef fish. The more common protogynous hermaphroditism, where females change into males, does not occur among clown fish. An intriguing question for further research is whether a juvenile clown fish can turn directly into a female or whether it must function first as a male.
17. The passage is primarily concerned with
analyzing the mutually advantageous relationship between two species
comparing two forms of hermaphroditism among clown fish
describing and explaining aspects of clown-fish behavior
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