Male Reproductive Tactics in the Libellulid Dragonfly Paltothemis Lineatipes: Temporal Partitioning of Territories

Abstract

AbstractMales of Paltothemis lineatipes defend stream-edge territories several meters in length. Receptive females fly to the stream to oviposit in very small patches of barely submerged fine gravel; each territory contains at least one but rarely more than two patches. Territorial males intercept incoming gravid females, copulate very briefly with them while hovering over a potential oviposition site, and then release their partners, which usually oviposit for less than 2 min before leaving the stream. Because mated females do not oviposit while in tandem with a male, neighboring territory owners sometimes succeed in stealing females before they have completed oviposition in their first mate's territory. Interrupted females sometimes are receptive, and may copulate with an intruder and oviposit in his territory. Gravid females arrive at the stream primarily in a 3 h mid-morning period during which time the density of territorial males is greatest. Fights for territories are most frequent early in the daily activity cycle, just prior to the time when receptive females are most likely to appear. There are many more males than sites with suitable oviposition substrate. Consequently competition for territories is intense, particularly at locations that attract relatively many females. From 2-4 males may claim favored territories in sequence on a given day, with the same males returning to partition ownership of the location temporally in the same order over several days. Temporal partitioning of certain territories in P. lineatipes appears to be a consequence of the males' ability to identify superior locations and superior times for territoriality, with the result that no one individual can monopolize a productive site for an entire daily flight period.