Cane Toads Get Osteoarthritis

In Bones, Bodies, and Disease Calvin Wells frequently mentions examples of pathology from the animal kingdom. For example, in discussing osteoarthritis Wells mentions that the condition has been observed in dinosaurs, Miocene gavials, crocodiles, and Pleistocene cave bears, cave hyenas, and Bos primigenius. We can now add Australian cane toads to the list.


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According to National Geographic a study is being published in PNAS (as usual, PNAS is taking forever to get the study online) that discusses the issue. According to National Geographic:

The toads haves severely impacted ecosystems in Australia. Predators–and sometimes pets–that eat toads die immediately from their poison, and the toads themselves feast on any animal they can fit in their mouths. Cane toads also compete with native frogs for habitat.

The result is that the cane toads are suffering from degenerative joint disease, mainly in the spine.
I mention that because PNAS does have an interesting article on the effects of cane toads on snake head size and body length the quote below is from the abstract:

Because snakes are gape-limited predators with strong negative allometry for head size, maximum relative prey mass (and thus, the probability of eating a toad large enough to be fatal) decreases with an increase in snake body size. Thus, the arrival of toads should exert selection on snake morphology, favoring an increase in mean body size and a decrease in relative head size.

That study showed that some species of snakes are adapting to the cane toads by reducing head size and increasing body length (which means they can’t swallow the toads).
At any rate, the new study examines the effect of the cane toad dispersal on cane toad morphology (according to National Geographic):

The fastest toads travel nearly half-a-mile (one kilometer) a night, he added. “Toads with longer legs are moving faster and traveling longer distances, while the others are being left behind,” he said. “It’s a classic evolutionary phenomenon, the evolution of the fastest.

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