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Re: Daphnia Generations
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?