Pedophylax esculentus is a common type of frog in Europe. It originated as a hybrid of two other frog species (P. ridibundus (RR) and P. lessonae (LL) ), but that’s not their fault. However, the way in which they continue the species is genuinely embarrassing, almost as bad as puppeteers.
P. esculentus ( genome RL) generally produces offspring by mating with another species, usually P. lessonae. In most populations, they produce gametes that only contain the R genome (the L genome is discarded): mating with P. Lessonae restores the L genome. Presto, more hybrids.
They can mate with others of their kind, but few tadpoles survive – essentially because the parental genome (R) does not go through sexual recombination – thus mutations have accumulated over the many generations since the original hybridization. Muller’s ratchet.
In eastern Europe, it’s the other way around: the L genome is clonal and the hybrids have to mate with P. ridibundus, with complex results (3/4 hybrids, 1/4 pure ridibundus).
And then some populations manage with a mix of diploid and triploid hybrids, which we’ll leave as an exercise for the reader.
Anyhow, the truly weird thing is, people eat these things.