Subject: Re: evolution of fungi
From: [email-masked] (john taylor)
Date: 17 May 1994 08:59:22 -0700
Newsgroups: bionet.mycology

Reply to Dave Haas

        The fungi are not alien, but probably constitute the sister group
to animals (Baldauf and Palmer, 1993; Wainright et al., 1993) .  They are
heterotrophs and export hydrolytic enzymes to break down polymers so that
the monomers can be imported.  Not too different from the animal feeding
strategy.  The fungi with the deepest divergences are aquatic and have
flagella (Chytridiomycota  (Berbee and Taylor, 1993; Bowman et al., 1992) .
 The common ancestor of fungi and animals probably shared a number of
characteristics with the modern chytrids and choanoflagellates
(Cavalier-Smith, 1987) .  Although the first fungi were aquatic, the number
of known marine fungi is smaller than one might expect, and many of them
appear to represent a recent adaptation to the marine habit  (Kohlmeyer and
Volkmannkohlmeyer, 1991)    Fungi may have originated as fresh water
organisms.

        Fungi live on dead biological matter and living organisms.  The
interface between these two substrates can be difficult to recognize, as in
the case of a fungus that makes toxins to kill the tissue of its host
before feeding.  At one other extreme are the symbiotic fungi, lichens,
mycorrhizal fungi, rumen chytrids and the like.  Many of the biotrophic
fungi are obvious parasites, and the symbioses probably represent cases
where the host-parasite relationship evolved to a balance.  All in all, I
doubt that mutualism is over represented in the fungi.  When your immune
system falters, an astounding number of previously benign fungi pose severe
problems  (Rinaldi, 1989) 

Baldauf, S. L., and J. D. Palmer.  1993.  Animals and fungi are each
other's closest relatives: congruent evidence form multiple proteins. 
Proc. Natl. Acad. Sci. USA. 90:11558-11562.
Berbee, M. L., and J. W. Taylor.  1993.  Dating the evolutionary radiations
of the true fungi.  Can. J. Bot. 71:1114-1127.
Bowman, B. H., J. W. Taylor, A. G. Brownlee, J. Lee, S.-D. Lu, and T. J.
White.  1992.  Molecular evolution of the fungi: relationship of the
Basidiomycetes, Ascomycetes, and Chytridiomycetes.  Mol. Biol. Evol.
9:285-296.
Cavalier-Smith, T.  1987.  The origin of Fungi and pseudofungi.  Pages
339-353. in Evolutionary Biology of the Fungi (A. D. M. Rayner, C. M.
Brasier and D. Moore, eds.).  Cambridge University Press, Cambridge. (check
current contents for more recent papers).
Kohlmeyer, J., and B. Volkmannkohlmeyer.  1991.  Illustrated key to the
filamentous higher marine fungi.  34:1-61. (earlier works have more on the
biology of these fungi)
Rinaldi, M. G.  1989.  Emerging opportunists.  Infectious Disease Clinics
of North America. 3(1):65-76. (check medline for more recent work in this
area)
Wainright, P. O., G. Hinkle, M. L. Sogin, and S. K. Stickel.  1993. 
Monophyletic origins of the Metazoa: an evolutionary link with fungi. 
260:340-342. 

--John Taylor

>      Let me begin by stating that I am not a mycologist but rather
>      a botanist with an interest in the higher fungi.  Fungal protists
>      are OK but the fungi, in my opinion, are as alien as the insects
>      and as such, from the human standpoint, are unique life forms.
>
>      My questions which are most probably elementary, are nevertheless,
>      to me - each a mystery.  They  concern the evolutionary history of
>      these chitinous critters.
>
>      Most terrestrial organisms have a fairly well established link to
>      the aquatic.  What about fungi?  As terrestrial organisms with
>      non motile gametes most are decomposers, yes?  Do fungi occupy the
>      same niche in marine ecosystems? If not what does?  Do we have any
>      fungal aquatic ancestors?  Also ...
>
>      I know an astounding number have formed micorrhizal associations
>      with higher and lower plants not to mention their role in lichens.
>      What is it in their constitution that makes fungi so compatible
>      with other organisms?  This is probably an unanswerable question
>      but go ahead and speculate (nobody reads this).
>       
2. 
                                                    
>      Anyone care to reply? 
>
>      Thanks in advance,
>
>===============================================================================
>=
>Dave Haas  [email-masked]           ()
>Department of Natural Sciences            (())
>Fayetteville State University            ((()))
>Fayetteville NC, 28301    USA           (((())))
>===========================================||==================================
>=

____________________________________
From:   John Taylor
        Department of Plant Biology
        111 Koshland Hall
        University of California
        Berkeley, CA  94720
        Tel (510) 642-5366
        Fax (510) 642-4995
        internet [email-masked]