Re: fossil lichens? (from N. Monks)

[N.MacLeod@xxxxxxxxx (N. MacLeod)]

Dear all,

I'm not a lichenologist (?), but as an ecologist, I am willing to bet that
their limited range...i.e. high-intertidal, bare rock, marginal, etc...is
to do with competition from vascular plants.

A lot of people, scientist included, have this idea that 'hardy' or
'pioneer' species like or are adapted for marginal habitats. It ain't so.
For hardy, read generalist or unspecialized species. As soon as a better
adapted plant turns up, and they will eventually, the lichens are
outcompeted.

Try Connell's work on barnacles for a similar scenario (e.g. Ecology
42:710-723). Back in the Lower Palaeozoic, vascular plants were less able
to compete, so why not have lichens colonizing non-marginal environments
with high fossilization potentials. Like estuarine mud flats, bogs, even
under-water.

The slow growth feature of modern lichens may be a result of this being the
only niche available to lichens today in the face of stiff competition. So
we need to be MUCH more open minded about what lichens were capable of
doing in the Lower Palaeozoic or Ediacaran.

Just a thought.

Neale

Neale Monks, Department of Palaeontology,
Natural History Museum, London, SW7 5BD
Internet: N.Monks@nhm.ac.uk
Telephone: 0171-938-9007

"...now Nature is having the last laugh. The freaky stuff is turning out to
be the mathematics of the natural world"

from 'Arcadia', by Tom Stoppard