NANFA-- Homogeneous Distributions

John B (
Sun, 21 Sep 2003 16:57:30 -0500

Also in Science is an amazing article that is related to the topics
currently being discussed on this site in recent weeks. We have focused
on the disappearance of species and the introduction (exotics). This
article "Homogenation of Fish Faunas Across the United States Science --
Frank J Rahel 288 (5467): 854". The article compares fish diversity
from state to state at the beginning of the 20th century to today (y
2000) and does a state by state comparison of similarity.

It is very striking the effect that man has had on Fish biodiversity.
Unlike marine fishes and Birds and other verebrates, Fish have a very
difficult time migrating to other ranges due to environmental changes.
Changes in distribution (i.e. introductions to ranges where fish were
previously unknown) cannot be explained by global warming, El Nino,
Tornados, Water spouts etc. Man has had the greatest impact on fish in
the last century period. The most striking examples ar the similarity
between fish diversity when comparing Arizona and Montana. At the
beginning of the 20th century, the two states had 0% similarity of their
fish faunas. Currently, they share 33 species, both game and non-game
species. Rahel's work also demonstrates that the greatest effect on
similarity was not exterpation but on introductions. Average similarity
amoung pairs of states is up 15.4 more species than before the time of

My take on the article suggest that homogenation is the higher priority.
Continued introductions make no sense if we want to maintain and help
restore indiginous populations of P. Waleka, Cyprinodon, Etheostoma,
Pecina, Noturus, Fundulus etc. It needs to stopped by legislation and

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