Variety is the spice of life: too many males, too little time...

April 23, 2008

Female Australian painted dragon lizards are polyandrous, that is, they mate with as many males as they can safely get access to. This promiscuous behaviour is often found in species where male quality is dubious and there are high levels of infertility in the male population. Female painted dragons possess the remarkable ability to store sperm inside their reproductive tract that remain viable for a considerable amount of time, so that the sperm of different males actually compete with each other to fertilise her eggs.

Male painted dragons are highly distinctive and brightly coloured and what is particularly fascinating about them is that they occur in two different colours - red or yellow-headed. From an evolutionary perspective this seems intuitively puzzling as usually natural selection does an excellent job of removing inferior versions of an organism out of the ensuing population, ensuring its ultimate demise. With painted dragon lizard males however, both versions persist in the population, suggesting that each type of male somehow manages to acquire a mate and successfully reproduce equally well.

Mo Healey, Tobias Uller and Mats Olsson of Wollongong University, carried out female choice experiments on single males of different colours, and discovered that females did not preferentially associate with either coloured male. However, when females were allowed to choose between pairs of males of the same versus different colours, they preferred to associate with male pairs that were polymorphic, i.e., one red and one yellow male. The level of individual recognition in this species is unknown and often when males and females assess each other in the wild it is initially from a distance, meaning that visual cues are very important.

Healey et al. propose that by mating with one yellow and then one red male (or vice versa), female painted dragons are making sure that they are in fact mating with two different males and not the same male twice. This preference could therefore contribute to the maintenance of both male types within the population.

Source: Wiley

Explore further: Scientists find new way to assess the health of vulnerable, valuable coastal habitats

Related Stories

Ants as a model of complex societies

August 5, 2015

In small plastic tubs lining the shelves of a basement laboratory at the University of Pennsylvania, a million organisms live in complex societies.

Insect decoys could protect ash trees

July 2, 2015

Emerald ash borers have no trouble reproducing themselves as they have now spread through half the United States, but duplicating effective emerald ash borer decoys is not quite as easy. Now, engineers have devised an inexpensive ...

Closing salvos in Silicon Valley sex bias case

March 25, 2015

Rival attorneys launched closing salvos Tuesday at jurors who will decide whether a renowned Silicon Valley venture capital firm was a "boys club" that discriminated against women.

Recommended for you

Seeing quantum motion

August 28, 2015

Consider the pendulum of a grandfather clock. If you forget to wind it, you will eventually find the pendulum at rest, unmoving. However, this simple observation is only valid at the level of classical physics—the laws ...

Just how good (or bad) is the fossil record of dinosaurs?

August 28, 2015

Everyone is excited by discoveries of new dinosaurs – or indeed any new fossil species. But a key question for palaeontologists is 'just how good is the fossil record?' Do we know fifty per cent of the species of dinosaurs ...

0 comments

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.