MSc Student
Markus Grams1, Ambrosio Torres², Stefan Richter¹

¹ Allgemeine & Spezielle Zoologie, Universität Rostock, Universitätsplatz 2, 18055 Rostock, Germany
² Centre for Integrative Biodiversity Discovery, Museum für Naturkunde, Invalidenstraße 43, 10115 Berlin, Germany

Abstract

While originating from comparative morphological studies, beginning in the 1990s, cladistics (or phylogenetic systematics) became largely dominated by the use of molecular markers. It started with using just a few genes (i.e. 18S rRNA, 28S rRNA), but soon included multi-gene analyses and nowadays reached the extent of what became known as phylogenomics. Although it is a desirable approach to combine both morphological and genetic data in cladistic analysis, these types of datasets were significantly unbalance towards genetics already in the early beginnings, not to mention now with modern phylogenomic datasets that easily outweigh morphology. Soon, morphology not only became unattractive due to being too laborsome, but also lost credibility with respect to the often very different results of genetic analyses. Yet, morphology still has much to offer for the interpretation of phylogenetics, far beyond being a source of character mapping on genetic trees.

The malacostracan crustaceans exemplify decades of dissent between the phylogenetic results from morphological and genetic analyses that only in recent years now started to align to some extent. On that basis, we attempt a combination of a high standard up-to-date morphological matrix including representatives of all orders of Malacostraca with a newly assembled phylogenomic dataset tailored to the morphological taxon sampling. Starting from a simple analysis without any balancing between the two datasets, further approaches and new methodologies are applied. Based on the presented results, problems and potential of the different approaches are discussed.