JESSUP, STEVEN LEE. Biology Department, Southern Oregon University, Ashland, OR 97520. - Phycobiont fidelity in Umbilicaria.
Lichen phycobionts have
generally been thought to have low fidelity with mycobionts at the
species rank, but that assertion has been based on scant empirical
evidence. Phycobionts from populations of several Umbilicaria
species growing both sympatrically and in disjunct single-species
populations were isolated from lichen thalli and cultured. DNA was
extracted from cultures and characterized with RAPD fragment profiles.
Distinct phycobiont haplotypes are identified. Phycobiont haplotype
fidelity within and among mycobiont lineages is analyzed. Do
mycobiont and phycobiont lineages mix at random, or is there some
degree of fidelity of phycobionts within and among species of
Umbilicaria, or within and among mixed and single-species
populations? Does large-scale geographic structure of phycobiont
haplotypes correspond with geographic distributions of species in
Umbilicaria? Evidence from fidelity analysis of phycobiont and
mycobiont lineages across a wide geographic sample in
Umbilicaria provides an empirical foundation for
generalizations about these and other questions pertaining to
cospeciation, host-switching, and geographic structure of symbiont
diversity in lichens.
Key words: cospeciation, lichen, phycobiont, RAPD, symbiosis, Umbilicaria