The newts of the genus Taricha come armed with a powerful neurotoxin that they excrete from their skin called tetrodotoxin. The toxin is a chemical defense used against predators. In a study published November 28 in the journal Frontiers in Amphibian and Reptile Science, a team of biologists describes how female Taricha newts produce more tetrodotoxin than males. The findings suggest that tetrodotoxin is not only a line of defense, but also a kind of signal.
[Related: Poisonous animals probably took their sweet time developing unappetizing bright colors.]
“It had long been considered that newts’ toxin concentrations do not change in their lifetime and that males and females tend to have the same toxin concentrations. Now, we have shown that female newts actually contain more toxin than male newts,” study co-author and University of California, Davis ecologist and evolutionary biologist Gary Bucciarelli said in a statement. “We observed significantly greater and more drastically fluctuating toxin concentrations in females, which may have numerous causes, like mate selection.”
Totally toxic traits
Tetrodotoxin is also found in the deadly blue-ringed octopus, pufferfish, and some shellfish and amphibian species. In sexually reproducing animals, sexually dimorphic traits like canine tooth size and vibrant color can be a key to reproductive fitness and their survival. These differing traits are believed to increase an individual’s chances of producing the next generation of offspring.
Scientists already knew that Taricha newts had other sexually dimorphic traits, such as mass, size, and tail height, so they were curious to see if toxin production also differed between the sexes.
In the study, the authors took tetrodotoxin samples from more than 850 newts across 38 different sites in California. They noted the sex, size, mass, and tail height for all of the animals, and if the female newts were pregnant. The newts that…
Read the full article here