The Sex Life of a Hypolimnas bolina Male Seems to be Going Well
What happens in a group of butterflies when there are not enough males to mate? Female great eggfly butterflies(Hypolimnas bolina) don’t seem to have a problem fertilizing their eggs. Even in a population where females outnumber males 40 to 1 the females still are able to fertilize their eggs with success. How is this done?
In this week’s issue of Current Biology and Scientific American News, a study examimed these questions. Because of a parasite called Wolbachia, which kills males before they even hatch, the male population has decreased to an extreme low level. Even though females greatly outnumber the males within the population, there is no decrease in female mating. Female mating has actually increased. This is due to a small package of male sperm called a spermatophore. When a female mates with a male this spermatophore is inserted inside her. Since males have to comply with the female’s excessive need to mate they are unable to generate a suitable size of spermatophore. Smaller spermatophore have fewer sperm, and that makes it harder for the female to fertilize her eggs. The female is able to measure the diameter of the spermatophore. The females are able to sense a smaller diameter in the spermatophore and collect more sperm to fertilize her eggs. Not just one male’s spermatophore is large enough to fulfill the needs of the female great eggfly. Although the male's spermatophore is smaller than usual, due to the males capacity of sperm and sperm production, the population does not suffer in following generations.
This story seems like a continuous cycle. The females are mating with as many males as they can due to the small spermatophore size, but the trouble arises due to the fact that the spermatophore is small because the males have to impregnate females so often, and they are not able to build up a large enough spermatophore to fertilize a female. Although it interesting to notice that the population of the great eggfly has not suffered even though there is highly uneven ratio offemale and male Hypolimnas bolina.
Posted by Chris
posted by PWH @ 10:37 PM
9 comments
9 Comments:
This is very intersting. Is any research being done on the Wolbachia? It seems to me if less and less males are born every year and producing smaller spermatophores, then within a certain number of generations there will be no more males left, and thus the species will die out. I'm sure there must be a way to protect the male eggs from Wolbachia and save the species. I wonder if anyone is looking into it. Tricia Carlson
wow, what a fascinating topic! it's amazing that the population size hasn't decreased, despite the problems that the males are having.
I find it remarkable that the male has to put forth so much effort in impregnating the female and yet there is still an increase in female mating. One would think that with the smaller size of the spermatophores as well as less males being produced that the population of this species would in fact decrease. Very interesting topic!
detroyr6
This topic is very interesting especiall when concidering how the females are compensating for the lack of males left in the population. I think it is amazing that the females are able to tell how much spermatophers they have, and how much more they need to impregnate themselves. This topic does, however, make me wonder about the future of this species and how quickly the males are "disappearing".
It's very suprising that the butterfly population has not suffered, despite the small number of male butterflies. Have males always been present in smaller numbers, or is their decline in population a recent event? It seems like since the butterfly population has not decreased that the males production of many small spermatophore may be an adaptation. Could it be that it takes less energy to make many small spermatophores instead of a few large spermatophores, so there is a trade-off? Just out of curiosity why do the Wolbachia only affect males? Does the parasite affect any other kinds of butterflies. Nice article.
Michelle Emery
I don't understand how scientists can determine that the females can detect the diameter of the spematophore. Also, if the Wolbachia were eliminated and the male population increased would this enable the size of the spematophore to increase? And would the population of females as well as female mating go down? It seems the females are very persistent and it is interesting to see how they modified their behavior to sustain their species. I also would like to know why the Wolbachia only affect the males I think that's an interesting topic to research. Very interesting topic though. Lindsay Dawson
This concept was hard for me to grasp at first. It seems as though female butterflies adapted to this problem surprisingly fast. A 40 to 1 ratio between male and female is an enormous gap in population, so it was hard for me to believe that their population did not suffer the least bit. But then again, once I thought about it, it seemed more feasible to me.
If one was to compare this problem on a human scale, one male to 40 females could hypothetically not affect birth rates. Aside from the fact that it would be morally wrong, I believe humans could also overcome this problem as the butterflies did. This made me accept the fact that despite the uneven male to female ratio, the butterfly population did not suffer, yet.
Nabil Benhayoun
This subject is vert interseting. One thing that is still unclear to me is, why do the Wolbachia kill off the males and not the female egg flys? Is there something more appealing about the males to the Wolbachia? Or have the females adapted to be able thwart off this enemy? An adaptation in the female flys would account for their ability to be more fit in this situation of survival. However it would be very interesting to learn more about why the males are killed by the Wolbachia at such young stages and the females aren't.
I think it is quite intriguing to see that there are such populations of species in which females outnumber males at such a large ratio, yet the actul population does not suffer. I wonder how come there are less and less males being born, or is there any particular reason why there are so few males that are able to impregnate the females.
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