Exploring species diversity within the order Halymeniales (Rhodophyta, Florideophyceae) of predominantly southeastern Australia using molecular-assisted alpha taxonomy and multi-gene phylogenetics

Abstract

Appreciation of the diversity of biological life is fundamentally important not only to our understanding of the world around us, but imperative in management of our environments and assessing our impact upon same. Systematics and taxonomy are the disciplines dedicated to characterizing the myriad species we share our planet with. This study was undertaken to assess species diversity in an order of red algae, the Halymeniales (Florideophyceae, Rhodophyta), from predominantly Australian collections. Modern methods have vastly increased the amount of data available to assess species diversity, with molecular barcoding being the fastest and simplest tool with which to quickly sequence large volumes of collected material and sort them into genetic species groups. From over 400 individual samples, the findings from barcode data revealed that the Halymeniales has many overlooked species (approximately doubling the biodiversity). The combination of molecular barcoding and traditional morphological assessment of anatomical features (viz. ‘alpha taxonomy’) is both more powerful than traditional taxonomy and more meaningful than simply knowing how many species groups there are, especially where novel species are uncovered by the molecular barcode. This combined approach, dubbed ‘molecular-assisted alpha taxonomy, or MAAT, was employed in this study and presented in the following chapters are many detailed observations of both existing species and species previously unknown to science. Phylogenetic analyses placed this Australian biodiversity into a global evolutionary context, with data from Australian halymeniaceous taxa added to Halymeniales data from extra-Australian locations. Phylogenetic results indicated that some reorganization at the genus-level within the order is required, which is detailed in Chapters 2-4. Presented here is the largest and most comprehensive molecular study of the Australian Halymeniales to date, using the combined approach of Molecular-assisted alpha taxonomy and phylogenetics to more accurately conceive the biodiversity of this large and morphologically diverse order of red algae.