[Taxacom] Antarctic dispersal (was: Another blow to vicariance in ratite evolution

[Ken Kinman]

Hi Mike,                                       The Crossosomatales southern clade is probably only about 80 million years old, so dispersal to Madagascar seems to be a good bet (and I believe it also dispersed to the Seychelles and Mascarene islands as well).  This clade probably existed in Antarctica and Australia (fossil pollen records), so the current distribution is no doubt a combination of early vicariance, later dispersals, and then extinction in intervening areas (including Antarctica and Australia).  I don't know much about the beetle family Chaetosomatidae, but perhaps Stephen Thorpe might have an opinion on that.   
         In any case, since only that beetle family has the same distribution as the elephant bird-kiwi clade, I would certainly not call that much of a pattern!!!  And the elephant bird-kiwi clade is probably even younger than 80 million years old, so dispersal of a flighted ancestor (of kiwi and elephant birds) from Antarctica in the early Cenozoic seems a very probable hypothesis, and again followed by extinction of the clade in Australia (due to competition with other ratites) as well as extinction in mainland Africa (due to competition with early ostriches).  
        So if there is a pattern to be seen in such cases, I would suggest that Antarctica is going to be a major factor, and that the massive extinction of the biota in Antarctica during the early-to-mid Cenozoic (and paucity of a known fossil record there) makes vicariance more appealing than it actually is for many taxa.  In particular, the multiple losses of flight among ratite taxa makes perfect sense to me.  Why John calls such suggestions ignorant (much less stupid) baffles me.                            ----------------------------Ken Kinman 
                                                                   
Date: Mon, 9 Jun 2014 11:12:39 +1200
Subject: Re: [Taxacom] Another blow to vicariance in ratite evolution
From: m.j.heads at gmail.com
To: kinman at hotmail.com; taxacom at mailman.nhm.ku.edu

Hi Ken, On p. 74 of my 2014 book I cited the beetle family Chaetosomatidae, known only from Madagascar (Malgassochaetus) and New Zealand (Chaetosoma, Chaetosomodes). A similar pattern in plants occurs in the southern hemisphere clade of Crossosomatales; it's in Madagascar (also the adjacent coast of Africa and Cape Town) (Aphloia, Geissoloma) , New Zealand (Ixerba) and New Caledonia (Strasburgeria). (Both examples are cited, with references, in my 2014 book, p. 74).  


On Mon, Jun 9, 2014 at 10:42 AM, Ken Kinman <kinman at hotmail.com> wrote:

John,       I would be interested in examples of those taxa with a Madagascar-New Zealand relationship.                                -----Ken


John wrote:

 There are other taxa with a Madagascar (and or S Africa) - New Zealand relationships and they are perfectly concordant with geologically mediated origins. Perhaps instead of stupid I should just say ignorant.









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-- 
Dunedin, New Zealand.  My recent books: Molecular panbiogeography of the tropics. 2012. University of California Press, Berkeley. www.ucpress.edu/book.php?isbn—80520271968
 Biogeography of Australasia:  A molecular analysis. 2014. Cambridge University Press, Cambridge. www.cambridge.org/9781107041028