Semalparity – Reproductive Suicide

Talk about sex till you drop or die making babies…God knows what other phrase one can make about this but this is very interesting.

Four different insect-eating marsupials (in the genuses Antechinus, Phascogale and Dasykaluta) from Australia, Papua New Guinea and South America have a mating strategy that is so bizzare, the males die shortly after the act. This is a classic example of semalparity or more commonly, reproductive suicide.

While reasons to why this is happening are still being debated, studies have shown that this is not a sacrifical act to ensure survival of offsprings, although females tend to come into heat around about the times when insect populations are at their peaks, however corelations to food supply does tend to be a factor. In a recent study published in the journal Proceedings of the national Academy of Sciences, all females tend to come on heat at the time when insect populations (food supply) are at their peaks. This means that the breeding season is very short and males will not have the luxury of taking their time with a group of females over a long period of time – competition among males is intense.

To pull off this super-sex feat, male testosterone levels skyrocket, ultimately disabling their immune systems. They then compete not by fighting but by producing the most sperm to ensure survuval of their genes. Acts of mating can last for up to 12 hours to decrease chances of the females mating with another.

To these animals, a larger testis size to body size is adventageous as it produces the level of testosterone requiresd or these long bouts and produces enough sperm to ensure survival of their genes but it comes at a cost – semalparity.

Adopted from  These Marsupials Spend About A Month Having Sex and Die Right After


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