Does promiscuity prevent extinction?

Feb 25, 2010
These are Drosophila pseudoobscura mating. A new study by the Universities of Exeter and Liverpool, UK, on these fruitfly suggests promiscuous females may be the key to a species’ survival. Credit: University of Exeter

Promiscuous females may be the key to a species' survival, according to new research by the Universities of Exeter and Liverpool. Published today (25 February) in Current Biology, the study could solve the mystery of why females of most species have multiple mates, despite this being more risky for the individual.

Known as 'polyandry' among scientists, the phenomenon of females having multiple mates is shared across most animal species, from insects to mammals. This study suggests that polyandry reduces the risk of populations becoming extinct because of all-female broods being born. This can sometimes occur as a result of a sex-ratio distortion (SR) chromosome, which results in all of the 'male' sperm being killed before fertilisation. The all-female offspring will carry the SR chromosome, which will be passed on to their sons in turn resulting in more all-female broods. Eventually there will be no males and the population will die out.

For this study, the scientists worked with the fruitfly pseudoobscura. They gave some populations the opportunity to mate naturally, meaning that the females had multiple partners. The others were restricted to having one mate each. They bred several generations of these populations, so they could see how each fared over time.

Over fifteen generations, five of the twelve populations that had been monogamous became extinct as a result of males dying out. The SR chromosome was far less prevalent in the populations in which females had the opportunity to have multiple mates and none of these populations became extinct.

The study shows how having multiple mates can suppress the spread of the SR chromosome, making all-female broods a rarity. This is because males that carry the SR chromosome produce only half as many sperm as normal males. When a female mates with multiple males, their sperm will compete to fertilise her eggs. The few sperm produced by males carrying the SR chromosome are out-competed by the from normal males, and the SR chromosome cannot spread.

Lead author Professor Nina Wedell of the University of Exeter said: "We were surprised by how quickly - within nine generations - a population could die out as a result of females only mating with one partner. Polyandry is such a widespread phenomenon in nature but it remains something of an enigma for scientists. This study is the first to suggest that it could actually save a population from extinction."

Explore further: In battle of the sexes, a single night with a New York male is enough to kill

Related Stories

Why the best things come to those who wait

Oct 20, 2006

Pushing to the front of the queue is not the best ploy for males who want to propagate their genes according to scientists from the University of Exeter.

Sex is thirst-quenching for female beetles

Aug 28, 2007

Female beetles mate to quench their thirst according to new research by a University of Exeter biologist. The males of some insect species, including certain types of beetles, moths and crickets, produce unusually large ejaculates, ...

Good males are bad fathers

Jun 25, 2009

Contrary to predictions, males of high genetic quality are not very successful when it comes to fertilizing eggs. A new study on seed beetles by Swedish and Danish scientists Göran Arnqvist and Trine Bilde shows that when ...

Recommended for you

Do you have the time? Flies sure do

8 hours ago

Flies might be smarter than you think. According to research reported in the Cell Press journal Current Biology on May 28, fruit flies know what time of day it is. What's more, the insects can learn to con ...

Barking characterizes dogs as voice characterizes people

11 hours ago

An international group of researchers has conducted a study on canine behavior showing that gender, age, context and individual recognition can be identified with a high percentage of success through statistical ...

Bird beaks feeling the heat of climate change, say scientists

13 hours ago

While the human population grapples with ways to counter the effects of climate change, Deakin University research has discovered that birds might have been working on their own solution for the past 145 years – grow bigger ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.