[Taxacom] Origin of New Caledonian Biogeography

Robin Leech releech at telusplanet.net
Mon Nov 17 23:13:34 CST 2008

Dear All,
         Concerning the biological disjunction along the West Caledonian
 fault, John Grehan says that  "It may have undergone 150-200 km of
 lateral movement and it is suggested that this has caused the biological
 disjunction by pulling populations apart."
        However, given the accretionary nature which he attributes to
 New Caledonia's geology, I would suggest that it is probably not this
 "lateral movement" which has caused such biological disjunctions, but
 rather differences in the ability of certain organisms to tolerate
 extremely ultramafic soils (often deadly to species not adapted to
 them).  The lateral movement itself is probably far too slow
 geologically to account for these distributions, while soil chemistry
 differences would probably be a much greater factor.  In other words, it
 is more ecological than geographical.   I wonder if Heads (and Grehan)
 took this into account?                             ---------Ken Kinman

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