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 21 staying in copula DHJanzen100614.jpg high resolution
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Why do the males stay in copula all night and all the next day, despite the fact that sperm passes from him to her in a few minutes? The best clue is that in those species of saturniid moths that are personally protected by mimicry or by directly obnoxious chemistry, the males do not stay in copula for more than a few minutes. It is the cryptic species that remain attached to each other for the remainder of the night and all the next day. I suspect that the male stays attached the remainder of the night after copulating (and fertilizing the female) not because that is of direct signficance, but rather that is the way to insure that he is attached at dawn. In the real world, his chances of mating are well less than 50%, and the chance of finding another female that night very remote, so the fact that he has found a female is probably his only chance for contribution during that 24 hour period. Furthermore, at that time, his entire potential fitness is tied up in her during that first day after mating. If she survives that day, he survives. The two of them together, as in this image, appear to be a cluster of dead leaves. If a scrutinizing bird or monkey detects that it is instead a moth - potential food - it grabs. Half the time the predator will get the male, and if so, the female goes free (upon being grabbed, they both let go of each other). In other words, the reason for staying with the female is to raise her chances of surviving that first day (which is the most important one because she will lay half or even more of her eggs that following evening). His chances of being found by a predator are probably the same whether in copula or single, so he probably is not losing anything by staying in copula for nearly 24 hours. To repeat, what he HAS lost is the chance to find yet another female that same night, but since the calling females are available for only a few hours of the night, and most are in copula within minutes of beginning calling, his chances of a second mating that same night are very low indeed. |
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