How important is phylogenetic history in explaining character states in pleurocarpous mosses?

Abstract

A redundancy analysis (RDA) with following forward selection and variance partitioning was performed to evaluate whether character state variation in pleurocarpous mosses is best explained by higher level taxonomic position or a selected set of environmental parameters. The studied explanatory parameters explain ca. 30% of the total character state variation. Taxonomic position, reflecting the phylogenetic component, is the most important among the studied explanatory parameters, and the phylogenetic component on its own is relatively more important in explaining the variation in the gametophyte than in the sporophyte. Among the environmental parameters, the general habitat parameter was the most important, followed by the climatic zone, and the wetland to nonwetland gradient. In the RDA, gradients of the sporophyte character states are more important than those of the gametophyte. Those of the sporophyte relate to the degree of sporophyte specialization, whereas those of the gametophyte relate to characters associated with water conduction. Phylogenetic time lags are likely to account for the strong influence of the phylogenetic component in most cases, because correlations between taxonomic position and environmental parameters were very few, whereas convergent or parallel evolution is likely to explain the similar states found in strongly specialized sporophytes.