RE: Interesting article re rapid evolution/speciation

From: bivalve (bivalve@mail.davidson.alumlink.com)
Date: Tue Jul 15 2003 - 20:03:33 EDT

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    Relatively small DNA variation within as species can reflect a number of factors. The species may have originated relatively recently, with little time for divergence. The species may have a relatively slow rate of genetic change. The species may have had a very small population at some point, such that most variation was eliminated. The species may be highly mobile, preventing isolated populations from developing distinctive genetic patterns. Finally, there may be strong selective pressures favoring stability over mutation.

    For humans versus Caribbean anoles, I am not certain about the relative time of origin. Humans have relatively long lifespans, and reproduction is generally a major time of genetic reshuffling, so the much fewer human generations relative to anole generations over time would tend to promote slower change in us. Some models suggest a population bottleneck for humans, but I do not know how well-supported those are at present. Humans are certainly more mobile than anoles, so totally isolated subpopulations are unlikely to develop in humans. I do not know of any particular selective pressure for humans but not anoles; it would depend in part on what genes they look at.

        Dr. David Campbell
        Old Seashells
        University of Alabama
        Biodiversity & Systematics
        Dept. Biological Sciences
        Box 870345
        Tuscaloosa, AL 35487-0345 USA
        bivalve@mail.davidson.alumlink.com

    That is Uncle Joe, taken in the masonic regalia of a Grand Exalted Periwinkle of the Mystic Order of Whelks-P.G. Wodehouse, Romance at Droitgate Spa

    ---------- Original Message ----------------------------------
    From: "Debbie Mann" <deborahjmann@insightbb.com>
    Date: Tue, 15 Jul 2003 11:56:12 -0500

    >So, is there a scientific reason for there not being species diversification
    >in humans? Or should we look for a spiritual one?
    >
    >-----Original Message-----
    >From: asa-owner@lists.calvin.edu [mailto:asa-owner@lists.calvin.edu]On
    >Behalf Of Jim Armstrong
    >Sent: Tuesday, July 15, 2003 10:50 AM
    >To: asa@calvin.edu
    >Subject: Interesting article re rapid evolution/speciation
    >
    >
    >
    >Biologists find unexpected rapid evolution in Caribbean lizards
    >http://www.eurekalert.org/pub_releases/2003-07/wuis-bfu071303.php
    >
    >
    >
    >
                     

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