RE: Misunderstood Cichlids

From: Vincent Campbell (
Date: Fri Aug 31 2001 - 11:04:18 BST

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    Subject: RE: Misunderstood Cichlids
    Date: Fri, 31 Aug 2001 11:04:18 +0100
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            <There's no mystery regarding the independent evolution of similar
    jaws for
    > exploiting various kinds of food found in each lake. What's mysterious,
    > and
    > what I alluded to in my reference to this article, is the uncanny
    > resemblance in color pattern on the scales of the cichlids. It's not at
    > all
    > clear from the article why living in similar environments would cause
    > these
           amazingly similar appearances.>

    Read it again, and look at the images again. First, as the sentence
    accompanying the picture says, this is a product of 'occupying similar
    ecological niches'. Second, look at the picture whereby colour similarity
    does not mean identical, e.g. the ones at the top Julidochromis and
    Melanochromis, both with long horizontal stripes running the length of the
    body, except the latter fish also has a stripe on its upper fin, where the
    former does not.

    Why the variation? The article indicates that it's at least in part a
    product of sexual selection. If you look at that diagram, 7 of the 10
    species shown have fish with vertical stripes along their body, suggesting a
    female preference for vertical stripes. Why? I'm speculating now, although
    I could check with my colleagues down the corrider in Stirling Uni's
    Aquaculture department if you like, don't lines on fish work the same way as
    on animals like Zebra- they break up the shape/outline of the fish when
    moving to confuse predators? Since many of the ecological niches occupied by
    these different species are very similar, just in different lakes, and the
    species share common ancestry, is it really any mystery that similar
    patterns have emerged. I don't think so. After all what is clear is that
    these species are not the same genetically that is, and note the article
    states that all these diverse species do not interbreed.

    Indeed, it seems to me that cichlids offer more problems for MR because of
    the rapid rate of speciation- where are all the past images of the multitude
    of new species to have appeared, particularly those that have emerged in
    recently isolated stretches of lake?


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