>>I know this forum is for purist...well mainly for "purist" but has anyone seen the ball carpet hybrid in the "hybrid discussion" section...this is really interesting. We now know the genus "Python" can be successfully bred with other Python species, Moriela (and so probably also with Liasis, since Liasis has been bred with Moriela) and Aspidites...anyone else seeing the taxonomic implications if the young are fertile?

It has been pointed out that all taxonomic categories higher than species are of artificial human construct. Your message intimates that if different species are not supposed to be able to interbreed, then different genera should not be able to interbreed either, and higher taxonomic categories than these would be even less likely to be able to interbreed.

Genus is a taxonomic category that is traditionally used to group closely related species that are morphologically not very different from one another. Species that are genetically closely related but morphologically disjunct are often placed in different genera. A good example is the chimps and the gorilla. They are genetically close but morphologically dissimilar, so they are placed in different genera of their own. Success in producing interspecific hybrids depend on a lot of different factors, and these factors often have little to do with morphological similarities.

Two morphologically similar species, such as Hyla chrysoscelis and Hyla versicolor, are often unable to interbreed because of polyploidy. The hybrids of this diploid-tetraploid species pair have low viability as larvae and they are infertile even if they survive to adulthood because they are triploid. Triploid species in general are unable to undergo meiosis to produce viable gametes (although some triploid plant species modify their process of gamete production to get around this). So, you see, morphological similarity, which is often the basis for classifying higher taxa, is simply not a reliable measure of whether two species are likely to produce interspecific hybrids.

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