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Abstract
of paper 3:
Werth, S., H. H. Wagner,
F. Gugerli, R. Holderegger, D. Csencsics, J. M. Kalwij, and C. Scheidegger.
submitted. Quantification of local and landscape-level dispersal
of a lichen epiphyte indicates higher establishment limitation than
dispersal limitation. Ecology.
Dispersal is a process critical
for the dynamics and persistence of metapopulations, but is difficult
to quantify. The old-forest lichen Lobaria pulmonaria
has been suggested to be limited by insufficient dispersal ability.
We analyzed 240 DNA extracts derived from snow samples by a
L. pulmonaria specific RealTime-PCR assay of the ITS region
allowing for the discrimination among propagules originating from
a single, isolated source tree or propagules originating from
other locations. Samples which were detected as positives by RealTime-PCR
were additionally genotyped for six L. pulmonaria microsatellite
loci. Both molecular approaches demonstrated substantial dispersal
from other than local sources. In a landscape approach, we additionally
analyzed 240 snow samples with RealTime-PCR of ITS and detected
propagules not only in forests where L. pulmonaria was
present, but also in large unforested pasture areas and in forest
patches where L. pulmonaria was not found. Monitoring
of soredia of L. pulmonaria transplanted to maple bark
after two vegetation periods showed high variance in growth among
forest stands, but no significant differences among different
transplantation treatments. Hence, it is probably not dispersal
limitation hindering colonization in the old-forest lichen L.
pulmonaria, but ecological constraints at the stand level
which can result in establishment limitation. Our study exemplifies
that care has to be taken to adequately separate the effects of
putative dispersal limitation from a limitation of establishment.
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