biflora has been homogenized through gene conversion or loss of loci to the single repeat typical of its paternal parent, as has been documented in some allotetraploids (e.
Fluctuating climatic conditions and reoccurring glacial cycles during the Pleistocene may well have favored the persistence of genetically rich allotetraploids over their diploid progenitors still recovering from post-dispersal genetic bottlenecks, just as polyploidy may have contributed to the success of genome-doubled lineages over diploids during the K-T mass extinction (Fawcett et al.
ascendens is ah allotetraploid derived through ancient hybridization between two diploid species.
This problem is compounded in allotetraploids, in which the ranges of morphological characters overlap those of the parental diploids.
In the hybrids between diploid species of Secale (R genome) and tetraploid species of Hordeum, believed to be segmental allotetraploids
(modified H genomes) [ILLUSTRATION FOR FIGURE 3A, B, G, H OMITTED], it can be directly observed that only the chromosomes from the Hordeum genomes are involved in chiasma formation (Petersen, 1991).
The origin of the allotetraploid
species of Gossypium L.
is their fertile, allotetraploid
hybrid, and at least one sterile, triploid backcross hybrid was reported.