July 2013

Froad

Can cane toads cross-breed with native frogs?

Answer

Emerald-spotted Treefrog (Litoria peronii) The frog is an Emerald-spotted Treefrog (Litoria peronii). It’s a very pale individual, but the green spots can still be seen. The slightly ‘warty’ skin on the back of this individual is typical of the species. Cane Toads (Rhinella marina) can not successfully breed with any of our native frogs. This is not for lack of trying; there are several documented incidents of male toads grasping frogs in amplexus (the amphibian mating embrace).

One of the common definitions of a ‘species’ is that individuals of the same species produce viable or fertile offspring.

One good example of a species is the domesticated dog. A Great Dane and a Pug don’t look anything alike, but they can produce fertile puppies, so they are the same species Canis lupus familiaris.

A good example of interspecies breeding is the Mule, which is a cross between two different species; a female horse, Equus asinus, and a male donkey, Equus caballus. Almost all mules are sterile and cannot interbreed successfully. If you want another mule you need a horse and donkey. Mules do not have their own scientific name but are referred to as Equus asinus x Equus caballus.

Back to our frogs; the Emerald-spotted Treefrog is not only a different species to the Cane toad it is in an entirely different family (Hylidae) to the Cane Toad (Bufonidae), so they are certainly incapable of interbreeding. However, after saying all of this there are always exceptions to the rule in Biology, and recently Ring-Species have been found in bird and lizard populations but this will have to be for another Question of the Month.

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