Re: NANFA-- Flagfin-Bluehead hy....What!?

John B (bongi_at_cox-internet.com)
Sun, 22 Feb 2004 21:53:37 -0600

There are actaully a number of ways to estimate the time of divergence.
One method is Restriction Fragment Polymorphism analysis on
mitochondrial DNA (mtDNA). The mtDNA is extracted from the cells of each
fish and exposed to restriction enzymes. These enzymes are used because
they "hunt" out specific patterns in the loop of mtDNA and clip it
resulting fragments. For instance and enzyme called Ecor1 might look
for a specific sequence AATT on the mtDNA and clip it between the A and
the T (this is not a real example because I don't remember the real
sequences). There are many different enzymes that can be used. These
fragments are then compared to other species. The rate of mutation of
mtDNA is known and relatively constant. The mutations can then be back
calculated with the time of divergence calculated. The mtDNA is
inherited from the female always so we wind up looking at the history of
the female population.
In vertebrates geneticists use the Y-chromosome because it is male
inherited and they can focus on specific genes found on the Y. Using
PCR, polymerase chain reaction, the DNA can be amplified to illustrate
differences in the genes on the Y. Cytochrome c (i think it's c) is a
specific gene in mtDNA that can be analysed in different species to
determine relatedness and time of divergence. They use PCR to work on
that as well.

Its not all that much different from what you see on TV CSI and other
forensic shows highlighting DNA fingerprinting. They also use DNA
fingerprinting on Texas Bass in their sharelunker program to determine
if the fish are Northern or florida strain.

John

Mysteryman wrote:

>PKUKULS_at_cs.com wrote:
>
>
>>Does anyone know or know a reference for the evolutionary distance (years
>>since the species diverged) between Pteronotropis hubbsi and Pteronotropis welaka?
>>
>>
>>
>Who says they ever did? They may have diverged from a common ancestor,
>but I seriously doubt that either one is derived from the other.
>Okay, I'm being a smart aleck, but who the heck could possibly know the
>answer to a question like that? I'd like to know that one myself.
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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