Fig. 4
Theoretical reconstruction of Varanidae sex chromosome evolution. Ancient amniote sex chromosome diverges where different orthologs diverged into sex roles in other lineages. The varanid Z and W chromosomes were likely a homomorphic pair, then independently in the Varius, Gouldii and Odatria lineages the W underwent species independent degradation and accumulation of repeats. Some species in each lineage also maintained the homomorphic pair (V. komodoensis, V. citrinus show no repeat accumulation and V. gouldii exhibit either the earliest stages of repeat accumulation). Other species such as V. acanthurus, V. varius and V. rosenbergi all exhibit heteromorphic W chromosomes, but V. rosenbergi and V. acanthurus do not share repeat content and V. varius still remains to be characterised.
