Rock-wallaby interbreeding causes rethink on evolution

October 7, 2015, Australian National University
Scientists have discovered that rock-wallabies living in north east Queensland are sharing genetic material despite belonging to six different species.

Scientists have discovered that rock-wallabies living in north east Queensland are sharing genetic material despite belonging to six different species.

These results suggest that the evolution of these iconic Australian marsupials is far more complex than the long-held theory of how species originate.

"Understanding these evolutionary processes is pretty fundamental in biology because it helps us define what a species is and understand how different species form," said lead researcher Dr Sally Potter from The Australian National University (ANU).

It was previously thought that mating between different rock-wallaby species could not result in fertile offspring. This is because of the differences in the way their is packaged into chromosomes.

"We expected that the differences in chromosomes would block between different species, but when we delved a bit deeper we found a lot of gene flow," Dr Potter said.

Whilst examples of gene flow between closely-related species can be found elsewhere in the animal kingdom, it was not expected within species with such small population sizes and differences in chromosome shape and number.

"There are six species of rock-wallaby in north east Queensland, and these probably have the most complex chromosomal diversities within Australian marsupials," Dr Potter said.

"Rock-wallabies are a very interesting system to explore. It's exciting because it's an iconic Australian marsupial and it brings our research to the forefront of evolutionary theory."

One explanation for why the different rock-wallabies share genetic information could be the unique environment of the Queensland wet tropics. The six different species of rock-wallabies live within little patches of rocky outcrops and could be locally adapted.

Because they are in small populations, this may allow the chromosome differences to fix in populations more than other species.

As many of rock-wallabies are endangered, understanding their biology is important for conservation.

Additional studies of the genetics of these rock-wallabies are now underway by the ANU, University of Canberra and Australian Museum Research Institute, to gain further insights into the mechanisms behind these fundamental biological processes.

The research, resulting from a collaboration between the Australian Museum Research Institute and ANU, was published in The Royal Society journal Biology Letters.

Explore further: Kangaroos abound but fears abound for smaller cousins, warns WWF

More information: Gene flow despite complex Robertsonian fusions amongst rock-wallaby (Petrogale) species, Biology Letters, rsbl.royalsocietypublishing.or … .1098/rsbl.2015.0731

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1 / 5 (5) Oct 07, 2015
Which invites us to revisit Eugene McCarthy and our own genesis.
"Please stop telling God how to run a universe Albert."
5 / 5 (5) Oct 07, 2015
The six different species of rock-wallabies live within little patches of rocky outcrops and could be locally adapted.

Interesting - little patches of rocky outcrops in a desert acting like islands. Their environment would then be similar to Darwin's finches, which also exhibit significant interspecies gene flow and hybridization.

See Evolution of Darwin's finches and their beaks revealed by genome sequencing: http://www.nature...20150219
1 / 5 (4) Oct 07, 2015
There is no such thing as "species". I think our POV is particularly disadvantaged by being the only member of our genus.
4.2 / 5 (5) Oct 08, 2015
@animah: I noticed that too, unsupported claims of "causes rethink on evolution" in the title came down to the reality of "examples of gene flow between closely-related species can be found elsewhere". Darwin finches is a good example!

So to the critics née cranks in at least one case:

It is easy to test that species is useful as "basic units of biological classification", first because they find such use but also because they allow us to make the most precise observations known in science, the robust topology of phylogenetic trees. For an example, another article from today, the bird tree. This time with a correct title: "Group builds most comprehensive family tree of birds to date". [ ]

If species didn't exist, we couldn't make such trees. It is the areas of incipient speciation and in non-sexual species that provides some fuzziness.
5 / 5 (3) Oct 08, 2015
@Torbjorn: Agree. This "no such thing as X" is also a very old argument that has been rehashed countless times across many scientific categories. A great example is color: there is obviously no such thing as individual color as the spectrum is continuous.

So all categorizations are artificial. Big deal. It's not like scientists don't know it and are incapable of thinking outside the box. However there is also great utility in these categories, just like thinking in terms of individual colors is incredibly useful.

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