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Science Frontiers ONLINE No. 82: Jul-Aug 1992 |
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For some, sex = death
It has long been known that the males of some species of marsupial mice mate in their first year and then die off completely, leaving the perpetuation of their species to their male progeny. Females of these species usually survive to breed a second and even third year. The poor males, however, succumb due to "elevated levels of free corticosteroids in the blood and associated disease such as hemorrhagic ulceration of the gastric mucosa, anemia, and parasite infestation." In short, they seem programmed to die after mating, like the male octopus. And one wonders why evolution has wrought this mass die-off.
In their studies of marsupial mice, C.R. Dickman and R.W. Braithwaite have extended the phenomenon to two new genera: Dasyurus and Parantechinus. They have also found that the phenomenon is a bit more complex. First, in P. apicalis, the male die-off occurs in some populations and not others. In D. hallucatus, the die-off may occur in the same population in some years and not others. Furthermore, the females of this species may on occasion all die off, too -- but after giving birth, of course.
(Dickman, C.R., and Braithwaite, R.W.; "Postmating Mortality of Males in the Dasyurid Marsupials, Dasyurus and Parantechinus," Journal of Mammalogy, 73:143, 1992.)
Reference. The mass die-off after reproduction or "semelparity" is covered in more depth in BMF25 in our catalog: Biological Anomalies: Mammals II. For ordering information, visit: here.