That you don’t see males around when a female gives birth or lays eggs doesn’t mean that a male wasn’t involved. Females of many species can store sperm for long periods, sometimes their entire lives. Queen honeybees, for instance, go on a single “nuptial flight”, and the the sperm they gain on that flight is enough for the rest of her life, which can be several years.
A rattlesnake (Crotalus adamanteus) is making the news with this point. A female that had been isolated for five years recently had nineteen little snakes. After having been alone for so long, parthenogenesis seemed a possible candidate to explain the happy occasion.Not so. Genetic tests showed the offspring had genes from another animal besides momma, so this female had mated at some time in the past. How far back? Not known.
All of this means that determining parthenogenesis is trickier than it first appears.
Crayfish can also store sperm (Albaugh 1973), but how long is the upper limit? I’m not sure. So pet owners, just because the lone crayfish you got a while ago had babies doesn’t mean it’s a Marmorkrebs or is reproducing asexually. It may have just been biding its time.
References
Albaugh DW. 1973. A case of long-term sperm retention by a female crayfish (Decapoda, Astacidae). The Southwestern Naturalist 18: 97-98.
Booth W, Schuett GW. 2011. Molecular genetic evidence for alternative reproductive strategies in North American pitvipers (Serpentes, Viperidae): long-term sperm storage and facultative parthenogenesis. Biological Journal of the Linnean Society: In press. http://dx.doi.org/10.1111/j.1095-8312.2011.01782.x
Photo by OZinOH on Flickr; used under a Creative Commons license.
