Assessing the impact of morphology in combined phylogenetic analyses of bryophytes

JORGE R. FLORES; GUILLERMO M. SUAREZ; HYVÖNEN, JAAKKO

Congreso; XXXVIII Willi Hennig Meeting; 2019

The bryophytes constitute a morphologically diverse group of taxa comprising theearliest lineages of embryophytes (i.e., land plants) sister to vascular plants. In the last decades, phylogenetic analyses of sequence-level data have radically modified the systematic schemes within bryophytes and revealed a widespread pattern of conflict with morphology-based classifications. Data conflict between morphology and molecular data in bryophytes has become widely accepted. Yet, a comprehensive evaluation of character conflict has not been performed in the context of combined matrices. In this study, an extensive assessment of the impact of morphology on bryophyte phylogeny is conducted in the framework of a total-evidence approach using 10 published matrices. The analysed matrices spanned a wide range of bryophyte groups, taxonomic levels, gene sampling and number of morphological characters and taxa. Data conflict was addressed by measuring: (i) the topological congruence between individual partitions, (ii)changes in support values of the combined data relative to the molecular partition and (iii) clade stability. The association between these measures and the number of morphological characters per taxon (character/taxon ratio) and the proportion of non-fixed characters (i.e., polymorphism and missing data) was explored. In the individual partition analyses, the number of morphological characters and the proportion of non-fixed characters correlated positively withthe topological congruence. However, upon merging data, only the proportion of non-fixed data remained positively associated with support values and clade stability. The number of morphological characters, in contrast, led to negative or ambiguous responses, respectively. Several instances of taxon-specific responses were found as well, where certain datasets departed considerably from the general pattern. Hence data conflict should be carefully explored indifferent taxonomic groups. Overall, the results indicate that, despite the existence of character conflict between morphological and molecular data, the addition of morphology may still contribute to the inference of phylogenetic relationships of bryophytes. For example, the presence of non-fixed morphological character, usually considered the main conundrum in bryophyte systematics, influenced positively the phylogenetic inference. Our findings suggest that merely comparing (a) morphology-based classifications with molecular phylogenies or (b) the outcome from individual data partitions can misestimate data conflict. These findings imply that combined data analyses may provide conservative assessments of data conflict and, eventually, lead to a more accurate designation of morphological diagnosis.