Paul,
I suppose what you are suggesting would be possible (1) if the seasonal
changes in temperature & rainfall had always been the same since at least
Thomas Say's time, because the smaller & larger individuals have been
noticed at least since then; (2) if the snails reproduced not continuously,
but perhaps, once in the fall & once in the spring. So that the autumn
offspring would become smaller adults, perhaps because of cooler winter
temperatures, but the spring offspring would end up being larger adults. (On
the other hand, if the summers are drier, the spring offspring may end up
being smaller.)

Aydin

 -----Original Message-----
From:   Monfils, Paul [mailto:[log in to unmask]]
Sent:   Tuesday, November 27, 2001 1:30 PM
To:     [log in to unmask]
Subject:        Re: Polygyra cereolus/septemvolva

I wasn't necessarily suggesting that one population is immature - only that
the two populations were produced at different times, grew at different
rates due to environmental factors then present, and thereby attained
different average sizes before reaching maturity and terminating growth.

Paul M.

> ----------
> From:         Orstan, Aydin
> Reply To:     Conchologists of America List
> Sent:         27, November 2001 2:10 PM
> To:   [log in to unmask]
> Subject:      Re: Polygyra cereolus/septemvolva
>
> The size variation exists in adults which form a reflected lip after they
> stop growing.
>
>