The sex chromosomes offer a genetic apparatus involved in the sex determination in many dioecious organisms. There can be heterogametically defined males and homogametically defined females (the X–Y systems, e.g. humans and Drosophila) or vice versa as heterogametically females and homogametically males (the Z–W systems, e.g. chickens and silkworms). The origin and evolution of sex chromosomes ...

Turtles demonstrate variability in sex determination ranging from environmental sex determination (ESD) to highly differentiated sex chromosomes. However, the evolutionary dynamics of sex determining systems in this group is not well known. Differentiated ZZ/ZW sex chromosomes were identified in two species of the softshell turtles (Trionychidae) from the subfamily Trionychinae and Z-specific g...

found in iran, alburnoides bipunctatus and alburnus filippii. the chromosomes of these species were compared using giemsa staining and silver-staining (ag) techniques to describe the karyotypes. both species possess 2n = 50 chromosomes with no detected sex heteromorphism. the karyotypes were distinct, composed of 7 pairs of metacentric, 10 pairs of submetacentric, and 8 pairs of subtelo-acrocen...