Females in inbred populations become more promiscuous in order to screen out sperm from genetically incompatible males, according to new study by the University of East Anglia (UEA).
Published tomorrow in the journal Science, the findings help answer the puzzling evolutionary question of why females in most species mate with multiple males even though a single male can provide full fertility and promiscuity can carry fatal risks for the female.
Using the red flour beetle as a model species, the researchers investigated the reproductive benefits of female promiscuity or 'polyandry'. Polyandry, where a female's eggs are fertilized by multiple fathers, is the norm in most species, from chimpanzees to chickens, salmon to sea urchins. While biologists have recorded significant costs to females of this mating pattern, even death, these new findings show there can also be genetic benefits.
The UEA team found that the reproductive success of females in populations that were not inbred was identical, whether mating with one or five males. In inbred populations, females mating with just one male showed a 50 per cent reduction in the number of surviving offspring they could produce. However, inbred females who mated with five males managed to rescue their reproductive success back up to the levels of the non-inbred populations. The researchers checked to see if this could be explained by male infertility, but inbred males are just as fertile as non-inbred males. The effect was therefore due to genetic incompatibility between males and females, which is prevalent when a population becomes inbred. Importantly, the results show that females possess mechanisms that allow them to filter in the genetically most compatible sperm to produce more viable offspring.
Having made this discovery, the researchers then went on to create deliberate genetic bottlenecks in populations of flour beetles and demonstrated for the first time that af
|Contact: Simon Dunford, Press Officer|
University of East Anglia