It's a very fascinating subject. I envy you that you're able to study this
stuff for a living. I only able nibble at it a bit in my spare time.
Well I've got to go now (a bunch of people are coming over for Mother's
Day). Thanks again for the information,
Mark Otnes
Fargo ND
-----Original Message-----
From: Bruce Stallsmith <fundulus_at_hotmail.com>
To: nanfa_at_aquaria.net <nanfa at aquaria.net>
Date: Sunday, May 13, 2001 1:38 PM
Subject: Re: NANFA-- Great Lake Aquarium in Duluth Minnesota
>Lake Victoria has a very different history than the "true" Rift Lakes such
>as Malawi and Tanganyika. Victoria is very large (the size of Ireland) and
>not very deep, it's essentially a huge swamp. The other Lakes are very deep
>and have almost oceanic quality water; Tanganyika is probably about 12
>million years old, the others somewhat younger. There is evidence that
>Victoria comes and goes on a scale of about 10,000 years depending on
shifts
>in the climate. It apparently almost totally disappeared about 15,000 years
>ago when world climate was cooler which affected monsoon patterns around
the
>Indian Ocean. As the climate warmed and the continental icesheets
retreated,
>rainfall increased and the lake once again spread. Interesting geophysical
>history, to be sure, but even more interesting is genetic evidence that the
>400 species of endemic haplochromine cichlids in the lake today are all
>descended from one common ancestor at the time of the lake's rebirth. If
you
>analyze the DNA of existing fishes from the lake there's almost no
>variablity even between species that appear and behave very differently.
The
>evolutionary history of such "species flocks" is one of the more
interesting
>studies in evolutionary biology today. (It probably has something to do
with
>regulatory functions in the DNA sequences, but that's another story.)
>
>--Bruce Stallsmith
>Huntsville, AL, US of A
>
>>One exhibit claimed that Lake Victoria was only 12500 years old and had
>>about 400 endemic fishes. Can anyone confirm this age for the lake for
me?
>>I thought the lake was a part of Africa's Rift Valley and would thus be
>>very
>>old. I also thought it would take longer than 12500 years for species to
>>evolve (even after taking into account year-around spawning).
>>
>>Mark Otnes
>>Fargo ND
>
>_________________________________________________________________
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>
>
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/----------------------------------------------------------------------------- /"Unless stated otherwise, comments made on this list do not necessarily / reflect the beliefs or goals of the North American Native Fishes / Association" / This is the discussion list of the North American Native Fishes Association / nanfa_at_aquaria.net. To subscribe, unsubscribe, or get help, send the word / subscribe, unsubscribe, or help in the body (not subject) of an email to / nanfa-request_at_aquaria.net. For a digest version, send the command to / nanfa-digest-request_at_aquaria.net instead. / For more information about NANFA, visit our web page, http://www.nanfa.org