Maybe you have heard about sex-switching species – frogs, shrimps, even tropical fish such as coral reef fish. These species manage to switch their genders from either male to female, or female to male. Key motivation behind this behavior is obvious – to maximize breeding. For example, under a environmental condition that, among 10 african reed frogs, there is one male frog and the other nine are female, apparently a bigger reward will be given to one female frog who decides to switch her sex to male. In addition it is also seen as an action of balancing the gender ratio in a group.
However, one species on earth is not jealous of this “gift”, not because there is never a shortage of males, but because they, the females, create husbands from scratch all by themselves.
Here we are, looking at the extreme haplodiploid case of Histiostoma murchiei – a mite parasitic in the cocoons of earthworms. A lone female lays a certain of eggs to produce few haploid males who will later mate with her “within 3 or 4 days of being laid as eggs” – then die-off. After that, the female would be able to lay many more eggs which are exclusively diploid, producing around 500 long-lived females – sounds weird to human, but true, these new baby girls are fathered by their dead brothers.
Histiostoma Murchiei is powerful at reproduction as they do not even need to be fertilized to lay eggs – known as parthenogenesis. In fact, despite the “dramatic incest act” of Histiostoma Murchiei, Parthenogenesis is a perfectly normal trait which is also seen to occur in some other invertebrates such as aphids(greenflies), Daphnia(water fleas) and rotifers. Driven by nature, nurture or both, species gained such ability to successfully reproduce even under harsh circumstances such as the lack of male.
“Cruel” examples, judged from human’s perspective, among species are not hard to notice: Lover-killer – Black Widow，Husband-eater – Mantis, Second child-abandoner － Giant Panda….. However, we need to try to understand from these species’ point of view, thus reproduction is the big picture, and sacrifices are, sometimes, very necessary.
- A MITE PARASITIC IN THE COCOONS OF EARTHWORMS by James H. Oliver, JR. Department of Entomology, University of kansas, lawrence
- 10 craziest Animal behavior, http://www.2spare.com/item_55014.aspx