However , not all polyploids are reproductively isolated from their parental plants , and gene flow may still occur for example through triploid hybrid x diploid matings that produce tetraploids . However , not all polyploids are reproductively isolated from their parental plants , and gene flow may still occur for example through triploid hybrid x diploid matings that produce tetraploids , or matings between meiotically unreduced gametes from diploids and gametes from tetraploids ( see also hybrid speciation ) .