Schematic idiograms showing some steps proposed in the differentiation process of the ZZ/ZW sex pair. The origin of the ZZ/ZW sex pair from the protosex chromosome of the Characidium species. Centromeric region (blue); 18S rDNA site (green); W specific probe region (red); probable Z speciation genes region (purple).

 
 
  Part of: Pucci MB, Nogaroto V, Bertollo LAC, Moreira-Filho O, Vicari MR (2018) The karyotypes and evolution of ZZ/ZW sex chromosomes in the genus Characidium (Characiformes, Crenuchidae). Comparative Cytogenetics 12(3): 421-438. https://doi.org/10.3897/CompCytogen.v12i3.28736