Hybridogenesis

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The hybridogenesis is a rarely occurring form of transfer of the chromosomes to the next generation. It can occur in organisms that are hybrids of different species, for example in the water frog : The pond frog is a hybrid form that emerged from crosses between the sea ​​frog and the small water frog . During hybridogenesis, the chromosome set of parent type 1 is completely eliminated, so that the germ cells take over the unchanged chromosome set of parent type 2. The pairing then takes place again with parent type 1, so that the mixed form is created again.

Since the chromosomes of parent type 2 are passed on unchanged from the hybrid, whereas the chromosomes of parent type 1 are created in the usual way by meiotic recombination , the children are half- clones . This mode of reproduction is therefore also called hemiclonal (from the Greek hemi = half). Hybridogenesis can occur in diploid and triploid pond frogs. In the latter case, eliminating a set of chromosomes before meiosis can prevent problems with meiotic pairing due to excess chromosomes.

Hybridogenesis has so far been discovered in frogs (see above) and fish ( Poeciliopsis monacha and Rutilus alburnoides ), but not in the other vertebrate groups .

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