The phenomenon of females having multiple partners, calledpolyandria, is found in most animal species, from insects to mammals. The study suggests that polyandry reduces the risk of populations going extinct due to generations of only females. This can sometimes happen as a result ofsex rate distortion chromosome SR,which results in all the “male” sperm on the Y chromosome being shed prior to fertilization. All female offspring would carry the SR chromosome, which would be passed on to their children, giving rise to more generations of females. Eventually, there would be no males left and the population would die out.
To confirm this hypothesis, the researchers worked with thefruit flyDrosophila pseudoobscura. They provided some populations with the opportunity to mate naturally, which meant that the females had multiple partners. The other flies were restricted to a single pair. The researchers raised several generations to see how they progressed.After 15 generations, five of the 12 monogamous populations had become extinct as a result of the death of the males.. The SR chromosome was significantly less prevalent in populations in which females could have multiple partners and none of these populations became extinct.
The results show that having multiple partners can suppress the expansion of the SR chromosome, making all-female generations a rarity. According to Nina Wedell, a researcher at the University of Exeter and responsible for the study, “we were surprised by how quickly, in nine generations, a population died as a result of females mating with only one male.” “Thepolyandry is a very widespread phenomenon in naturebut it remains a kind of enigma for scientists; this study is the first to suggest thatcould save a population from extinction“, Add.
