Scientists from The University of Queensland are the first in the world to discover why programmed suicidal reproduction is likely to occur in mammals.
from the has led research into why some small insect-eating marsupials such as antechinus escalate stress hormones during the breeding season, which leads to total immune system collapse, haemorrhaging, infections, and death after mating in all males.
鈥淭hese species experience extreme sexual behaviour," Dr Fisher said.
"Mating can go for 12 or 14 hours at a time and they have lots of partners. They use up all possible energy and body tissues on competitive mating, which causes synchronised death after mating in males.
"Males stop making sperm before the mating season and their testes disintegrate, so they are not even using energy on that during the mating period.
"But they can never reproduce again even if they do live.
鈥淧eople often think that males are sacrificing themselves to leave more food for the next generation, but that isn鈥檛 the reason for male die-off.
"It鈥檚 not altruism but sexual selection.
"We looked at about 50 species of insect-eating marsupials in South America and Papua New Guinea as well as Australia with a range of male survival, and we found that males of species with low survival or the extreme of suicidal reproduction have short mating seasons.
"Females synchronise reproduction to coincide with a predictable spike in food once a year in higher latitudes where these species live.
"Young weaned at this time are most likely to survive.
"Mating is timed so males must squeeze all of their effort into a short time and space, and they compete fiercely.鈥�
The research shows the importance of climate, and resolves the mechanism of sexual selection responsible.
"Males compete not by fighting, but by mating themselves to death because their sperm is in competition with the sperm of many other males," Dr Fisher said.
"Species with die-off have the largest testes.
鈥淪perm competition means that males with larger testes and better endurance succeed.
"Females not only benefit by weaning their young when there is most food, but also by promoting this extreme sperm competition, because the highest quality males father their young,鈥� said Dr Fisher.
Media: Dr Diana Fisher, 国产探花 School of Biological Sciences ARC Research Fellow, +61 7 3346 9004 or +61 43 506 6011, d.fisher@uq.edu.au
The research paper can be obtained from: Tracey Franchi, 国产探花 School of Biological Sciences Communications Manager, +61 7 3365 4831, t.franchi@uq.edu.au
About the 国产探花 School of Biological Sciences
Through research undertaken in the School, 国产探花 has been ranked by the 2012 National Taiwan University Rankings in the top five universities globally for research in ecology and environmental biology and in the top 18 universities globally for plant and animal biology. The 国产探花 School of Biological Sciences attracts researchers of world standing in a range of disciplines, with international leaders in many diverse fields. Our work spans the scales of biological organisation, from molecules and cells to organisms, populations, species and communities. With more than 150 researchers working in evolution, global change biology, ecology, aquaculture, animal behaviour, physiology, entomology, zoology, botany, genomics, development and conservation biology, our researchers and graduate scientists are well-equipped to make a real difference in contributing to solving global problems.
