Toxic toad evolves?

[Geoff Read]

An Agence France-Presse slant on a brief communication published in Nature
today.

Invasion and the evolution of speed in toads
Cane toads seem to have honed their dispersal ability to devastating
effect over the generations.
Benjamin L. Phillips, Gregory P. Brown, Jonathan K. Webb and Richard Shine
Abstract: http://info.nature.com/cgi-bin24/DM/y/eWxf0BgCJx0Ch0uxb0EG
Article: http://info.nature.com/cgi-bin24/DM/y/eWxf0BgCJx0Ch0uxc0EH

 Darwin's nightmare: toxic toad evolves to secure supremacy

Paris, Feb 15; Agence France-Presse -

Cane toads now have longer legs, which helps them spread
He's fat, ugly and poisonous - and he's mutating.

He's the cane toad (Bufo marinus), a species which was introduced into the
Australian state of Queensland 70 years ago to tackle insect pests in
canefields and has since become an ecological catastrophe.

Weighing in at to up two kilos, the unwanted anuran has extended its range to
more than a million square kilometres in tropical and sub-tropical Australia,
crushing native species in its relentless advance.

A team of toad watchers positioned themselves on the front line of the
invasion, 60 kilometres east of the city of Darwin, and for 10 months caught
toads, some of which they radiotagged and let loose again.

They were astonished to find that the creatures can hop up to 1.8 kms a night
during wet weather, a record for any frog or toad.

But even more remarkable was the discovery that the first toads to arrive at
the front invariably had longer hind legs than those which arrived later.

By comparison, the toads which are living in the long-established Queensland
colonies have much shorter legs.

The case is being seen as a classic example of Darwinian evolution - animals
that are stronger, faster or smarter are able to stake out new territory and
defend it against those that are weaker, slower or less astute.

The findings also neatly explain a puzzle surrounding the cane toad.

>From the 1940s to 1960s, the critter expanded its range by only 10 kms a year.
Today, though, it is advancing at the rate of more than 50 kms annually.

The reason: with longer legs, the mutating species is able to travel further,
faster.

The authors, led by Richard Shine from Sydney University's School of
Biological Sciences, say the cane toad is a chilling lesson for governments to
combat invasive species as soon as possible, "before the invader has had time
to evolve into a more dangerous adversary."

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--
  Geoff Read <g.read at niwa.co.nz>
  http://www.annelida.net/