Data from: Variation in Ricasolia amplissima (Scop.) De Not. in Norway and Europe – a mere response to climate?

Observations of two apparent phenotypic expressions (morphodemes) of the
composite thallus of the lichen-forming ascomycete species Ricasolia
amplissima (Scop.) De Not. (formerly Lobaria amplissima (Scop.) Forss.)
inspired us to investigate the morphological and genetic variation of the
species in Norway. The morphodemes differ in thallus shape and occurrence
of apothecia and/or cephalodia, each dominating in climatically different
parts of southern Norway. We investigated the morphology of herbarium
collections as well as fresh samples from various areas, including
localities where the two morphodemes occur together. The nrITS barcode
marker was sequenced to investigate the genetic variation along the
climatic gradient of the Hardangerfjord area. We also included barcode
sequences of specimens from other parts of the world in order to establish
if the Norwegian pattern of variation has a wider geographical
significance. Results suggest that the genetic variation found in
Ricasolia amplissima corresponds to morphology independently of
geography/climate. The two haplotype groups clusters in two distinct
sister clades, however, the within-species variation is too small to
justify taxonomic recognition. Specimens with the cephalodiate morphodeme
and its haplotypes are mainly found in the oceanic west, whereas specimens
with apotheciate morphodemes and its haplotypes occur mainly in the drier
eastern parts. The results can be interpreted as 1) immigration to Norway
from different gene pools in separate glacial refugia, or, 2) natural
selection for water efficient cephalodiate morphodemes in the oceanic west
and apotheciate (sexually reproducing) in drier suboceanic east parts of
Norway. We argue that within-species genetic variation should always be
considered before conservation actions such as transplants of lichen
thalli are taken.