Re: Daphnia Generations

[Billinet at aol_com]

Hi, Daniel,

All of my daphnia are descended from a few (200?) D. pulex that I ordered 
about five years age.  I've wondered if the lack of any new genes would 
eventually cause the culture to crash from inbreeding-related problems, but 
so far they remain healthy.

One thing that I've noticed is that the ones I raise outside in the summer 
are noticeably larger and lighter colored than their sisters who live in my 
basement.   I mix the colonies and they take on the physical characteristics
of their environment - the indoor ones move outside get bigger and paler and 
the outdoor ones moved inside get smaller and redder.

Both get the same kind of food, and algae isn't a significant factor outside.
I had attributed this to a response of individuals to an environmental change 
of some kind - maybe sunlight - as opposed to a genetic shift - it happens 
too fast, but maybe . . . 

What kinds of change have you observed?

Bill