Mating frequency and interspecific matings in some freshwater cyclopoid copepods.

Laboratory investigations with Cyclops vicinus and Metacyclops minutus documented that mating frequency decreased significantly after the initial mating, i.e. re-mating is relatively rare in cyclopoid copepods. Re-mating is unnecessary because females are able to fertilize multiple clutches of viable eggs from one insemination. Similar sized Cyclops vicinus and Cyclops furcifer interbreed frequently. Interbreeding does not occur when size differences and taxonomic differences are as great as between C. vicinus and M. leuckarti. In C. vicinus and M. leuckarti, the duration of the last mating phase (spermatophore transfer until release of the female) and consequently the duration of the entire mating process, is different. I conclude that the low re-mating frequency in cyclopoid copepods probably evolved to accelerate clutch production in unpredictable environments and to reduce predation risk. The occurrence of interspecific mating discourages the co-existence of similarly sized, related species. Mating behaviour may have a considerable influence on zooplankton community structure.