Snakes win over toxic newts in evolutionary arms race

March 11th, 2008 - 1:14 pm ICT by admin  

Washington, March 11 (ANI): In a new study by scientists, it has been suggested that snakes may have prevailed in the evolutionary arms race between predator and prey, taking the case of poisonous newts in particular.

Charles Hanifin, a postdoctoral scholar at Stanfords Hopkins Marine Station, has made the study, along with his co-authors.

According to the study, snakes have evolved resistance to the blowfish poison, tetrodotoxin (TTX), by preying on rough-skinned newts, which also secrete the toxin.

In fact, some populations of newts produce enough TTX to kill thousands of mice or 10 to 20 humans.

Throughout much of their shared territory, newts and snakes have been locked in a kind of arms race: TTX-resistant snakes cause natural selection to favor ever-more poisonous newts, and the new-and-improved newts drive selection for higher resistance in snakes.

Now, according to Hanifin, snakes in some areas may have prevailed in this evolutionary arms race.

Surprisingly, snakes in several geographic locations have developed such extreme resistance to TTX that newt production of the toxin cannot keep up.

At first glance, the newt and garter snake populations seem to be evenly matched. The most toxic newts are found in the same areas as highly resistant snakes, and areas without toxic newts house only non-resistant snakes.

Data on the garter snakes came from Hanifin’s collaborators, Edmund Brodie Jr. of Utah State University and Edmund Brodie III of the University of Virginia, who measured snake resistance to TTX by injecting the animals with the toxin and measuring how fast they subsequently slithered.

Although TTX does not kill resistant snakes, it often slows them down for a while. Less-resistant snakes move slower after TTX injection, and some are even temporarily paralyzed.

To get a closer look at the snake-newt interaction, Hanifin and colleagues tested 383 newts from 28 locations where the Brodies had previously examined garter snake TTX resistance.

Hanifin found that snakes were pulling ahead of the newts in several places.

In one third of the locations, the most toxic newt could still be eaten by the least resistant snake. This means that all snakes in the population do just as well regardless of their TTX resistance level, and there is no evolutionary pressure for the snakes to develop stronger resistance.

“In these areas, I think the snakes have won,” said Hanifin. (ANI)

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