MORPHOLOGICAL UNIFORMITY AMONG WIDELY DISJUNCT POPULATIONS OF THE RARE COPPER MOSS, SCOPELOPHILA-CATARACTAE (POTTIACEAE)

Eight morphological characters of the gametophyte generation and three of the sporophyte generation were measured in 15 plants from each of 76 populations of the rare and geographically disjunctive moss, Scopel ophila cataractae, in order to assess whether subtle differences exist between plants from widely separated populations. Plants were variabl e in all morphological traits, but most of the variation occurred amon g individual stems within populations and among populations within bro ad geographic regions. In spite of statistically significant differenc es between plants from widely disjunct regions (including different co ntinents) for eight of the 11 morphological traits, the percentage of the total variation attributable to regional differences was minimal. Little regional variation in individual traits was corroborated by mul tivariate analyses including UPGMA clustering and principal component analysis. Furthermore, the degree and pattern of correlations among mo rphological traits were remarkably similar in populations of plants se parated by thousands of miles. The general rarity and habitat specific ity of S. cataractae throughout its range suggest that widely disjunct populations have been continuously separated. This, combined with the present analysis of morphology, suggests that morphological diversifi cation may occur slowly in this moss.