The mating biology of a mass-swarming mayfly
1989; Elsevier BV; Volume: 37; Linguagem: Inglês
10.1016/0003-3472(89)90084-5
ISSN1095-8282
AutoresJ. David Allan, Alexander S. Flecker,
Tópico(s)Animal Ecology and Behavior Studies
ResumoThe males of many species of mayflies form dense aggregations, or swarms, to which females come to mate, typically at specific landmarks. This mating system was investigated in Epeerus longimanus, a mayfly of the western United States that forms swarms that are quite large. Swarms were found to occur primarily in clearings along the study stream, and certain sections consistently supported large or small swarms. The number of males was correlated with clearing size; in addition, the numbers of males attracted to artificil markers (sheets of plastic in a nearby meadow) increased with marker size. Thus, display habitats appeared to be patchily distributed and to limit swarm size at least locally. Collections of emerging nymphs demonstrated no association with swarm locations. Since adult mayfiles do not feed, it is evident that swarm locations are not explainable as feeding or emergence sites, but they do correlate with landscape features. The number of observed matings per swarm event was generally 5–20% of the estimated peak male density, despite a sex ratio at emergence of 1·2 males: 1 female. Survivorship of caged males and recaptures of marked males both indicate the likelihood that males are sufficiently long-lived to joins swarms on successive evenings, which may account for the low frequency of matings. The role of mate location in the evolution of swarming behaviour is discussed.
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