Researchers from the University of Queensland, the University of Sydney, and the University of Tasmania reported on the various factors that cause four different species of male insectivorous marsupials to have evolved suicidal reproduction (semelparity) in the Oct. 7, 2013, edition of the journal Proceedings of the National Academy of Sciences.
Four species of marsupial predators in Australia, South America, and Papua New Guinea were shown to have developed male suicidal reproduction in which males die after mating following a rise in stress hormone levels and immune system collapse. The highest rate of suicidal reproduction occurred in the Australian genera Antechinus (12 species), Phascogale (3 species) and, Dasykaluta (one species).
The researchers investigated habitat, seasonal effects on mating, female ovulation cycles, and male body dimensions in an effort to find the primary driver for male suicidal reproduction in a diverse set of marsupial species that are distantly related.
The species with the lowest male survival rate demonstrated a shorter mating season and larger testes in the males. The major driver for suicidal reproduction was found to be female promiscuity and the shortening and synchronizing of female’s annual mating period in favor of higher levels of sperm competition. The female’s choice of a mate favored suicidal reproductive behavior in the males.
The availability of food, climate, and the height of the animal’s habitat had a minimal effect on the suicidal reproductive behavior.
The research proposes to settle a fifty year argument about the cause of suicidal reproduction in marsupials.