Dying After Mating: Why it Happens to Some

CREDIT: Wikimedia Commons/Interllectual

Apparently, some male insect-eating marsupials, such as the mouse-like antechinus and the possum-like phascogales, have killer sex. In fact, the very act of mating with their own kind literally kills them.

According to a research published by the Proceedings of the National Academy of Sciences of the United States of America (PNAS) on Oct. 7, 2013, the animals mate in a frenzied manner to guarantee that their sperms are successful because they only have once a year to do so, due to the limited window of mating opportunity provided by their female counterparts. This results in death for most, if not all of the unfortunate animals.

"There's always a cost to reproducing - it's an energy expensive thing that animals do," said mammal ecologist and University of Queensland lead researcher Diana Fisher.

"But in this case they haven't spread out their effort over time, they do it all at once in a really short time. And they just die afterward."

"They have a nice temperament, they are very inquisitive little animals. They are quite interactive. It's a bit sad. But they don't know it's coming I suppose, it's just something that happens to them," she said.

The animals' high testosterone levels reportedly trigger a cascade effect of stress hormones, causing their immune systems to collapse and their body tissues to break down. Plus, they have lots of partners, which add up to the chaos.

The antechinus have notoriously long mating sessions, which last up to 12 or 14 hours. It shouldn't come as a surprise because they are one of the only semelparous mammals in the world, which means sex is a once-in-a-lifetime thing for them.

Before, scientists thought that the marsupials died because of fighting with each other, or to provide food for their offspring.

The study included researchers from the University of Tasmania and the University of Sydney. They compared 52 species of marsupials in Papua New Guinea, South America, and Australia. Their findings show that not all of the marsupials self-destructed after sex.

"We demonstrate that short mating seasons intensified reproductive competition between males, increasing male energy investment in copulations and reducing male post-mating survival," the paper said.