[Taxacom] Columbiformes, ghost moths, Madagascar, etc.

[Michael Heads]

Dear Ken,

 
 
The fossa may possibly have eliminated Columba from Madagascar, but Columba thrives in Africa where there are many different kinds of cats - five families of feliforms as opposed to just one (branching halfway up the phylogeny) on Madagascar - and it's hard to imagine that the fossa could wipe out Columba when these have not. 

 
Are there any areas or patterns where you accept a vicariance explanation for many of the groups? In most patterns the clades involved all show different degres of differentiation, so in an evolutionary clock model there cannot have been vicariance. This seems to be quite good evidence against a clock model. 

 
Michael


Wellington, New Zealand.

My papers on biogeography are at: http://tiny.cc/RiUE0

--- On Mon, 23/5/11, Kenneth Kinman <kennethkinman at webtv.net> wrote:


From: Kenneth Kinman <kennethkinman at webtv.net>
Subject: [Taxacom] Columbiformes, ghost moths, Madagascar, etc.
To: taxacom at mailman.nhm.ku.edu
Received: Monday, 23 May, 2011, 3:57 PM


Hi John, 
        No, it's not my imagination assuming that it
reflects reality, it's called brain-storming, imagining what MIGHT
reflect reality and thus possible areas for future study.  Frankly, my
brain-storming over the past 9 days were the result of your knee-jerk
reaction against the publication indicating that New World Crocodylus
species probably evolved from a transoceanic dispersal of the Nile
crocodile. First you railed against molecular clocks (which the paper
did not employ), and then you switched to the imperfect fossil record
(and you can invalidate almost any hypothesis if you assume a long
enough ghost lineage however unlikely it is). 
        Vicariance is fine where it is appropriate, but I just think you
put too much emphasis on vicariance (just as you apparently think I put
too put too much emphasis on dispersal).  But I am obviously not the
only one on Taxacom who thinks you far are too quick to criticize
dispersal.     

        ANYWAY, I have no definitive answer to the
absence of Hepialidae from Madagascar. However, just to brain-storm a
little, I would guess it could be related to the reason that Hepialidae
is absent (or apparently absent) from the west African tropics. I
suppose one possibility is that they are actually present in such areas,
but so cryptic or rare than they haven't been discovered yet. I would
tend to bet that this is the case for the west African tropics and that
they will be eventually be documented there.          
        In Madagascar, it could be that, or that they
never got there at all, or perhaps they tried to establish, but
predators got to them. The most likely predator to prevent them from
becoming established there might be bats. Lots of limestone caves on
Madagascar (compared to the African mainland) so probably a greater
concentration of insectivorous bats there (at least until humans entered
the picture). Bats love moths, and very primitive lepidopterans  like
Hepialidae no doubt lack the ability of more derived Lepidoptera which
can detect bat sonar and evolved avoidance strategies to counter bat
predation. Who knows?  It's just brain-storming that might possibly lead
to future research avenues into the absence (or at least apparent
abscence) of Hepialids on Madagascar.  Maybe I can come up with other
ideas upon further reflection.              
       As for Michael's problem of Columba being absent
from Madagascar, I frankly have no good hypotheses offhand. Perhaps
predators on Madagacar (like the fossa) could find Columba nests and
eggs more easily than those of more well-established Columbidae (like
Nesoenas).  No fossas on the Comoros that I know of.  But of the two
Columba species in the Comoros, one was clearly introduced by humans,
and the other (endemic) species is not doing so well, so maybe that
Columba endemic was just lucky enough to get to the Comoros, but didn't
have the "right-stuff" (or even the opportunity) to jump the gauntlet
onto Madagascar.  That's best I can do on that one offhand.      
             --------------Ken             
P.S.  But as Chris mentioned on the "Fly" thread, don't get too uppity
and critical of freebie advice and information.  There are a lot of
other activities (family history, gardening, family activities, etc.)
that I find more rewarding and a lot less aggravating than what I often
get on Taxacom.  I took a hiatus from biology during much of the 1980s,
and I am sometimes tempted to retreat from the aggravation once  again
(although at my age that might mean permanently).  But I am sure that
the strict cladists would be happy if that happened.                  
----------------------------------------------------------- 
John Grehan 
        It seems that Ken regards anything he imagines
as somehow reflecting reality - and to imagine anything other than they
are not in Madagascar because their ancestral range did not include what
later became Madagascar (or that they were there but became extinct).
Perhaps Ken could even imagine something similar for why ghost moths
(Hepialidae) are not in Madagascar, despite being from a group that is
recognized as having a Mesozic origin because of the early fossil record
of related groups. 


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