On Thu, 17 Jul 1997, Mark Rigby wrote:
> Hrmmm, well, just to play Devil's advocate, why could it not be that
> cercariae that encyst on something were derived from cercariae that
> encyst in another host? Thus, it would seem that there are 2
> 1) cercariae that encyst on something gave rise to cercariae that need
> another host
> 2) cercariae that encyst in another host gave rise to those that encyst
> on something.
The work has been done on this by plotting the "encyst on" or "encyst in"
character on the appropriate cladogram. Even though Brooks, O'Grady and
Glen, and Pearson and Gibson disagree on alot of things, the idea that
"encyst on" preceded "encyst in" is well supported by the phylogenies.