Die Tropenstation La Gamba

Die „Tropenstation La Gamba“ in Costa Rica – Wissenschaftlicher Bericht
GRUBE, M., BALOCH, E., LUECKING, R. 2002: Specificity of fungal-algal interactions on
leaves. - IMC7, Oslo.
Several types of algae are adapted to the growth on living leaves, coccoid green algae
and members of Trentepohliales being most common and also serving as photobionts of
lichen-forming fungi. Initials of these lichens need to form composite thalli with
appropriate algae in a relatively short time. Therefore, particular strategies are pursued
to ensure efficient dispersal and colonialization of leaves. Specific growth patterns of
trentepohlioid algae, found in both lichenized and non-lichenized forms, suggest that
foliicolous mycobionts have a high specificity for their photobionts. Adjacent freeliving
Phycopeltis colonies belonging to different morphotypes are not accepted as
photobionts by the same fungus. Different ecological preferences of photobionts
apparently shape the diversity of foliicolous lichens found in a given microhabitat. A
particular strategy regarding photobiont selection of lichens is found in lichenized,
foliicolous species of Chroodiscus, which grow facultatively parasitic on lichens of the
genus Porina. C. australiensis and C. coccineus show a high degree of host specificity:
C. australiensis parasitizes Porina mirabilis, whereas C. coccineus is specifically found
on P. subepiphylla. In genera of lichens, which include both lichenized and nonlichenized,
lichenicolous species (e.g. Arthonia), the latter take advantage of the host
photobionts.
Anschrift der Autoren:
M. Grube & E. Baloch
Institute of Botany, Holteigase 6, A-8010 Graz
martin.grube@uni-graz.at
R. Luecking
The Field Museum of Natural History
1400 South Lake Shore Drive
Illinois 60605-2496, U.S.A.
66