This study summarizes results of a DNA barcoding campaign on German Diptera, involving analysis of 45,040 specimens. The resultant DNA barcode library includes records for 2,453 named species comprising a total of 5,200 barcode index numbers (BINs), including 2,700 COI haplotype clusters without species‐level assignment, so called “dark taxa.” Overall, 88 out of 117 families (75%) recorded from Germany were covered, representing more than 50% of the 9,544 known species of German Diptera. Until now, most of these families, especially the most diverse, have been taxonomically inaccessible. By contrast, within a few years this study provided an intermediate taxonomic system for half of the German Dipteran fauna, which will provide a useful foundation for subsequent detailed, integrative taxonomic studies. Using DNA extracts derived from bulk collections made by Malaise traps, we further demonstrate that species delineation using BINs and operational taxonomic units (OTUs) constitutes an effective method for biodiversity studies using DNA metabarcoding. As the reference libraries continue to grow, and gaps in the species catalogue are filled, BIN lists assembled by metabarcoding will provide greater taxonomic resolution. The present study has three main goals: (a) to provide a DNA barcode library for 5,200 BINs of Diptera; (b) to demonstrate, based on the example of bulk extractions from a Malaise trap experiment, that DNA barcode clusters, labelled with globally unique identifiers (such as OTUs and/or BINs), provide a pragmatic, accurate solution to the “taxonomic impediment”; and (c) to demonstrate that interim names based on BINs and OTUs obtained through metabarcoding provide an effective method for studies on species‐rich groups that are usually neglected in biodiversity research projects because of their unresolved taxonomy.
Polyploidy is widely considered as a major process in the evolution of plants but the accumulation of polyploid species diversity is still controversial. Some recent studies proposed increased extinction risk in neopolyploids compared with their diploid ancestors. The high proportion of polyploid ferns is expected to be formed mainly by neopolyploids, whereas paleopolyploid species are predicted to be clustered in clades founded by whole genome duplications. Here, we test this prediction by exploring the evolution of polyploidy in the derived fern family Aspleniaceae. The family has a global distribution and shows the highest frequency of polyploid taxa among all ferns. To test the hypothesis, we obtained a comprehensive phylogeny using chloroplast DNA sequences of 883 specimens representing 292 species. All published chromosome counts were mapped onto this phylogenetic framework in order to explore the evolution of polyploids. We recovered evidence for several whole genome duplications in the history of Aspleniaceae. Phylogenetic relationships of polyploids exceeding the tetraploid level suggest that tetraploid Asplenium species may have replaced their diploid ancestors as the main evolutionary players in some clades of this family.
Recently, the Society of Vertebrate Paleontology (SVP) has sent around a letter, dated 21st April, 2020 to more than 300 palaeontological journals, signed by the President, Vice President and a former President of the society (Rayfield et al. 2020). The signatories of this letter request significant changes to the common practices in palaeontology. With our present, multi-authored comment, we aim to argue why these suggestions will not lead to improvement of both practice and ethics of palaeontological research but, conversely, hamper its further development. Although we disagree with most contents of the SVP letter, we appreciate this initiative to discuss scientific practices and the underlying ethics. Here, we consider different aspects of the suggestions by Rayfield et al. (2020) in which we see weaknesses and dangers. It is our intent to compile views from many different fields of palaeontology, as our discipline is (and should remain) pluralistic. This contribution deals with the aspects concerning Myanmar amber. Reference is made to Haug et al. (2020a) for another comment on aspects concerning amateur palaeontologists/citizen scientists/private collectors.
The processes that shaped the West Indian fern flora remain poorly understood. We attempt to investigate earlier biogeographical patterns described for the region using the genus Adiantum as model. These patterns propose that the West Indian fern flora has (1) an essentially continental rather than insular character, having a rich representation of species occurring in tropical America; (2) the Greater Antilles have a higher fern diversity and higher endemism than the Lesser Antilles, and (3) adaptive speciation has been an important process in shaping the fern diversity of the Greater Antilles.
Adiantum is a subcosmopolitan genus that comprises 200–225 species of which 33 occur in the West Indies. We compiled the most comprehensive molecular dataset of Adiantum available to date, including the chloroplast markers rbcL, atpA, atpB and trnL‐F of 407 accessions belonging to 101 species, 24 of which occur in the West Indies. Maximum likelihood and Bayesian inference approaches were applied to generate phylogenetic hypotheses. Divergence times were estimated using published substitution rates. Ancestral areas were estimated using BioGeoBEARS.
The extant West Indian Adiantum species originate from at least 17 predominantly Miocene immigration events, 11 from South America and six from Central America, in combination with two cladogenetic events. The Cuban endemics Adiantum alomae and A. sericeum, as well as the Greater Antillean A. deltoideum, A. cristatum and A. pyramidale first appeared during the Pleistocene. The emergence of A. alomae and A. deltoideum coincides with the formation of the karstic relief of the Cuban coasts.
Immigration, rather than cladogenesis, governed the evolution of the West Indian Adiantum species. Our results concur with theoretical models proposed for island communities, suggesting that geologically younger and smaller island assemblages mainly derive from immigration, whereas cladogenesis plays an important role in older and larger islands.
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