Research shows wallabies lose on the pokies

Jan 30, 2014
Research shows wallabies lose on the pokies

( —Biologists have discovered that a wallaby's perception of colour is more similar to a dog than a quokka, sparking questions as to why marsupial colour vision has evolved so selectively.

By developing a pokies-like game for the wallabies, the research – recently published in PLOS ONE by Curtin University's Dr Wiebke Ebeling and colleagues – was able to determine exactly what the animals saw and how their colour perception differed from other species.

"We trained tammar wallabies to respond to different colour stimuli by pressing switches on an automated experimental setup, similar to a poker machine," Dr Ebeling said.

"The most remarkable result was the determination of the 'Neutral Point' which describes a single colour that to wallabies looks identical to white, where the animals cannot make up their mind which switch to choose. In the case of wallabies, this was a shade of cyan (greenish blue).

"The presence of a Neutral Point makes wallabies appear special among . Their vision is more similar to a dog or horse rather than other marsupials, even their close relative the quokka.

"This study has raised new questions as to why good colour vision evolves so selectively and should be beneficial to the quokka but not the ."

Dr Ebeling said the team presented tammar wallabies with a choice between white and different yellows, greens and blues. When choosing the correct stimulus in the experiment, the wallaby would be treated with food, leading to an extremely accurate determination of the Neutral Point.

She said the presence of a Neutral Point, together with results from other colour-mixing and colour discrimination experiments, was typical for 'dichromats' - species with two colour-sensitive photoreceptor types in their retina. Whereas 'trichromats' like humans and other marsupials such as the fat-tailed dunnart, with one more photoreceptor type in their retinas, could not be confused as easily.

"The case of the wallaby is clear-cut now: it's a dichromat, but it still remains a mystery what exactly the additional photoreceptor in other marsupials is and why the wallaby should be the only one to miss it," Dr Ebeling said.

"This diversity will require more research by tracking down the elusive photoreceptor gene and examining the behavioural capabilities of other marsupials to confirm other species as trichromats."

She said behavioural experiments allowed shy and night-active species like the tammar wallaby to participate on their own terms and reveal their perception of colours.

"Our wallabies learned quickly and seemed to enjoy working on the machine and often did not bother actually eating the food - they just played for the fun of it," Dr Ebeling said.

Explore further: Captive-bred wallabies may carry antibiotic resistant bacteria into wild populations

More information: Ebeling W, Hemmi JM (2014). "Dichromatic Colour Vision in Wallabies as Characterised by Three Behavioural Paradigms." PLoS ONE 9(1): e86531. DOI: 10.1371/journal.pone.0086531

Related Stories

Tammar wallaby’s clever immune tricks revealed

Jul 11, 2011

( -- Until now, it was a mystery why many marsupials have two thymuses—key organs in the immune system—instead of the one typical of other mammals. Now postdoctoral researcher Dr. Emily ...

The climb to the pouch begins in utero

Mar 18, 2013

Scientists have visualised the short pregnancy of a small species of the kangaroo and wallaby family of marsupials, the tammar wallaby (Macropus eugenii), for the first time by high-resolution ultrasound. ...

The first kangaroo genome sequence

Aug 19, 2011

Kangaroos form an important niche in the tree of life, but until now their DNA had never been sequenced. In an article newly published in BioMed Central's open access journal Genome Biology, an international consor ...

Recommended for you

Male monkey filmed caring for dying mate (w/ Video)

Apr 18, 2014

( —The incident was captured by Dr Bruna Bezerra and colleagues in the Atlantic Forest in the Northeast of Brazil.  Dr Bezerra is a Research Associate at the University of Bristol and a Professor ...

Orchid named after UC Riverside researcher

Apr 17, 2014

One day about eight years ago, Katia Silvera, a postdoctoral scholar at the University of California, Riverside, and her father were on a field trip in a mountainous area in central Panama when they stumbled ...

In sex-reversed cave insects, females have the penises

Apr 17, 2014

Researchers reporting in the Cell Press journal Current Biology on April 17 have discovered little-known cave insects with rather novel sex lives. The Brazilian insects, which represent four distinct but re ...

Fear of the cuckoo mafia

Apr 17, 2014

If a restaurant owner fails to pay the protection money demanded of him, he can expect his premises to be trashed. Warnings like these are seldom required, however, as fear of the consequences is enough to ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Jan 31, 2014
another nail for those strange people that like to insist that humans are the only animal that likes to have a good time.

More news stories

Biologists help solve fungi mysteries

( —A new genetic analysis revealing the previously unknown biodiversity and distribution of thousands of fungi in North America might also reveal a previously underappreciated contributor to climate ...

Growing app industry has developers racing to keep up

Smartphone application developers say they are challenged by the glut of apps as well as the need to update their software to keep up with evolving phone technology, making creative pricing strategies essential to finding ...

Making graphene in your kitchen

Graphene has been touted as a wonder material—the world's thinnest substance, but super-strong. Now scientists say it is so easy to make you could produce some in your kitchen.