Quote Originally Posted by asplundii View Post
That is a fairly decent break-down. Only caveat I would put on it is that the sex part is incorrect with respect to ball pythons (really, all pythons and boas if you want to be technical) as balls are X/Y and not the Z/W that Komodos are

I thought everything was X and Y, at least within vertebrates, but its much more complex than that...

In snakes[edit]

Snake W chromosomes show different levels of decay compared to their Z chromosomes. This allows for tracking the shrinking of W chromosomes by comparing across species. Mapping of specific genes reveals that the snake system is different from the bird system. It is not yet known which gene is the sex-determining one in snakes. One thing that stood out was that Python show little signs of "W-shrinking".[6]
Boa and Python families are now known to probably have an XY sex-determination system.[17] Interest in looking into this came from female family members capable of parthenogenesis, or producing offspring without mating. In 2010 a female Boa constrictor that produced 22 female offspring in this manner was found in the wild. By then it was presumed that such a pattern was produced by WW chromosomes.[18] Python bivittatus and Boa imperator, similarly only produce female offspring; their genomes share male-specific single nucleotide polymorphisms identifiable by restrictive enzyme digestion. Their chromosomal origins, however, differ: Python's XY are similar to other snakes' ZW, while Boa XY maps to microchromosomes in other snakes.[19] The female-only pattern is in contrast to the ZW Colubroidean parthenogens, which always produce male (ZZ) offspring.[20]