Systematics and evolutionary history of Tanytarsus van der Wulp, 1874 (Diptera: Chironomidae)

Abstract

On the evolution and diversity of Tanytarsus non-biting midges / Evolusjon og mangfold hos fjærmygg i slekten Tanytarsus

As species are the fundamental unit of biodiversity, accurate species identification and delimitation are crucial in studies of evolution, ecology, agriculture and biodiversity. Over the last decade, advancements in DNA sequencing technologies, bioinformatics and computational biology have provided large amounts of molecular data and improved tools used to analyze them. Chironomid midges are common flies with worldwide distribution and immature stages often dominate the freshwater fauna in both abundance and species numbers. Tanytarsus is a megadiverse genus within the Chironomidae family with more than 400 named species. However, some species can be difficult to identify using morphology alone, and the evolutionary relationships among Tanytarsus and its closely related genera has been ambiguous. This thesis provides new knowledge of species boundaries in Tanytarsus midges, and new insights in the evolutionary relationships among related species within the group. Our findings based on molecular data indicate that the paraphyletic genus Tanytarsus most likely originated in the Palearctic and Oriental regions during the late Cretaceous and early Paleogene. DNA barcodes are very useful to identify and classify Tanytarsus midges, and can also detect hidden species or misidentifications. Thus, a DNA barcode reference library of Tanytarsus midges is an important asset for efficient identification of all life stages of these midges. However, DNA barcoding or morphological identification alone may fail to recognize closely related species, and I show that an integrative taxonomy combining morphological and multiple genetic data can improve our understanding of species boundaries. Furthermore, various species delineation tools were tested and shown to perform differently on the same molecular dataset of Tanytarsus midges. I believe that inclusion of more species from less sampled geographical regions will support, and perhaps refine the hypothesized evolutionary history of Tanytarsus