Here's a great article I just ran across. Yet another reason for TDS being a possible advantage, and it actually has empirical data to back it up too. Of all the theories I have heard regarding the advantages of TDS, I have never seen one with good evidence, or anything describing current sex ratios of the adults determining the sex ratios of the young.--It's mostly just been theories that made sense.

http://www.kingsnake.com/aho/pdf/menu3/robert2003.pdf

Rodney