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Concept: Biological classification


Studying and protecting each and every living species on Earth is a major challenge of the 21(st) century. Yet, most species remain unknown or unstudied, while others attract most of the public, scientific and government attention. Although known to be detrimental, this taxonomic bias continues to be pervasive in the scientific literature, but is still poorly studied and understood. Here, we used 626 million occurrences from the Global Biodiversity Information Facility (GBIF), the biggest biodiversity data portal, to characterize the taxonomic bias in biodiversity data. We also investigated how societal preferences and taxonomic research relate to biodiversity data gathering. For each species belonging to 24 taxonomic classes, we used the number of publications from Web of Science and the number of web pages from Bing searches to approximate research activity and societal preferences. Our results show that societal preferences, rather than research activity, strongly correlate with taxonomic bias, which lead us to assert that scientists should advertise less charismatic species and develop societal initiatives (e.g. citizen science) that specifically target neglected organisms. Ensuring that biodiversity is representatively sampled while this is still possible is an urgent prerequisite for achieving efficient conservation plans and a global understanding of our surrounding environment.

Concepts: Scientific method, Biodiversity, Conservation biology, Species, Science, Knowledge, Biological classification, Global Biodiversity Information Facility


Yponomeutoidea, one of the early-diverging lineages of ditrysian Lepidoptera, comprise about 1,800 species worldwide, including notable pests and insect-plant interaction models. Yponomeutoids were one of the earliest lepidopteran clades to evolve external feeding and to extensively colonize herbaceous angiosperms. Despite the group’s economic importance, and its value for tracing early lepidopteran evolution, the biodiversity and phylogeny of Yponomeutoidea have been relatively little studied.

Concepts: Evolution, Biology, Species, Insect, Phylogenetics, Lepidoptera, Biological classification, Ditrysia


Classification of species within the genus Salmo is still a matter of discussion due to their high level of diversity and to the low power of resolution of mitochondrial (mt)DNA-based phylogeny analyses that have been traditionally used in evolutionary studies of the genus. We apply a new marker system based on nuclear (n)DNA loci to present a novel view of the phylogeny of Salmo representatives and we compare it with the mtDNA-based phylogeny.

Concepts: DNA, Evolution, Molecular biology, Biology, Species, Phylogenetics, Order, Biological classification


Hierarchical classification (HC) stratifies and classifies data from broad classes into more specific classes. Unlike commonly used data classification strategies, this enables the probabilistic prediction of unknown classes at different levels, minimizing the burden of incomplete databases. Despite these advantages, its translational application in biomedical sciences has been limited. We describe and demonstrate the implementation of a HC approach for “omics-driven” classification of 15 bacterial species at various taxonomic levels achieving 90-100% accuracy, and 9 cancer types into morphological types and 35 subtypes with 99% and 76% accuracy, respectively. Unknown bacterial species were probabilistically assigned with 100% accuracy to their respective genus or family using mass spectra (n = 284). Cancer types were predicted by mRNA data (n = 1960) for most subtypes with 95-100% accuracy. This has high relevance in clinical practice where complete datasets are difficult to compile with the continuous evolution of diseases and emergence of new strains, yet prediction of unknown classes, such as bacterial species, at upper hierarchy levels may be sufficient to initiate antimicrobial therapy. The algorithms presented here can be directly translated into clinical-use with any quantitative data, and have broad application potential, from unlabeled sample identification, to hierarchical feature selection, and discovery of new taxonomic variants.

Concepts: Scientific method, Archaea, Organism, Species, Hierarchy, Data analysis, Taxonomic rank, Biological classification


Biodiversity today is huge, and it has a long history. Identifying rules for the heterogeneity of modern biodiversity-the high to low species richness of different clades-has been hard. There are measurable biodiversity differences between land and sea and between the tropics and temperate-polar regions. Some analyses suggest that the net age of a clade can determine its extinction risk, but this is equivocal. New work shows that, through geological time, clades pass through different diversification regimes, and those regimes constrain the balance of tree size and the nature of branching events.

Concepts: Biodiversity, Conservation biology, Evolution, Tropics, Taxonomy, Binomial nomenclature, Genetic erosion, Biological classification


Fossil palms provide qualitative evidence of (sub-) tropical conditions and frost-free winters in the geological past, including modern cold climate regions (e.g., boreal, or polar climates). The freeze intolerance of palms varies across different organs and life stages, with seedlings in particular less tolerant of sub-zero temperatures than adult plants, limiting successful establishment of populations while permitting adult palms to survive in cultivation outside their natural ranges. Quantitatively, palms indicate minimum cold month mean temperature (CMMT) at 2-8 °C in palaeoclimate reconstructions. These data have accentuated model-proxy mismatches for high latitudes during Paleogene hyperthermals when palms expanded poleward in both hemispheres. We constructed a manually filtered dataset of >20,000 georeferenced Arecaceae records, by eliminating cultivars. Statistically derived mean annual temperature, mean annual temperature range, and CMMT thresholds for the Arecaceae and lower rank subfamilies and tribes reveal large differences in temperature sensitivity depending on lower taxonomic classification. Cold tolerant tribes such as the Trachycarpeae produce thresholds as low as CMMT ≥ 2.2 °C. However, within the palm family, CMMT < 5 °C is anomalous. Moreover, palm expansion into temperate biomes is likely a post-Palaeogene event. We recognize a CMMT ≥ 5.2 °C threshold for the palm family, unless a lower taxonomic rank can be assigned.

Concepts: Species, Climate, Taxonomy, Temperature, Arecaceae, Taxonomic rank, Biological classification, Latitude


Phylogenetic hypotheses for the large cosmopolitan genus Hypericum (St. John’s wort) have previously been based on morphology, and molecular studies have thus far included only a few species. In this study, we used 360 sequences of the internal transcribed spacer (ITS) region of nuclear ribosomal DNA (nrDNA) for 206 species representing Hypericum (incl. Triadenum and Thornea) and three other genera of Hypericaceae to generate an explicit phylogenetic hypothesis for the genus using parsimony and model-based methods. The results indicate that the small genus Triadenum is nested in a clade within Hypericum containing most of the New World species. Sister to Hypericum is Thornea from Central America. Within Hypericum, three large clades and two smaller grades were found; these are based on their general morphology, especially characters used previously in taxonomy of the genus. Relative to the most recent classification, around 60% of the sections of Hypericum were monophyletic. We used a Bayesian approach to reconstruct ancestral states of selected morphological characters, which resulted in recognition of characters that support major clades within the genus and a revised interpretation of morphological evolution in Hypericum. The shrubby habit represents the plesiomorphic state from which herbs evolved several times. Arborescent species have radiated convergently in high-elevation habitats in tropical Africa and South America.

Concepts: DNA, Evolution, Biology, Organism, Species, Phylogenetics, Binomial nomenclature, Biological classification


BACKGROUND: Landscape ethnoecology focuses on the ecological features of the landscape, how the landscape is perceived, and used by people who live in it. Though studying folk classifications of species has a long history, the comparative study of habitat classifications is just beginning. I studied the habitat classification of herders in a Hungarian steppe, and compared it to classifications of botanists and laymen. METHODS: For a quantitative analysis the picture sort method was used. Twenty-three pictures of 7-11 habitat types were sorted by 25 herders. ‘Density’ of pictures along the habitat gradient of the Hortobagy salt steppe was set as equal as possible, but pictures differed in their dominant species, wetness, season, etc. Before sorts, herders were asked to describe pictures to assure proper recognition of habitats. RESULTS: Herders classified the images into three main (and 6 smaller) groups: (1) fertile habitats at the higher parts of the habitat gradient (partos, lit. on the shore); (2) saline habitats (szik, lit. salt or saline place), and (3) meadows and marshes (lapos, lit. flooded) at the lower end of the habitat gradient. Sharpness of delimitation changed along the gradient. Saline habitats were the most isolated from the rest. Botanists identified 6 groups. Laymen grouped habitats in a less coherent way. As opposed to my expectations, botanical classification was not more structured than that done by herders. I expected and found high correspondence between the classifications by herders, botanists and laymen. All tended to recognize similar main groups: wetlands, “good grass” and dry/saline habitats. Two main factors could have been responsible for similar classifications: salient features correlated (e.g. salinity recognizable by herders and botanists but not by laymen correlated with the density of grasslands or height of vegetation recognizable also for laymen), or the same salient features were used as a basis for sorting (wetness, and abiotic stress). CONCLUSIONS: Despite all the difficulties of studying habitat classifications (more implicit, more variable knowledge than knowledge on species), conducting landscape ethnoecological research will inevitably reveal a deeper human understanding of biological organization at a supraspecific level, where natural discontinuities are less sharp than at the species or population level.

Concepts: Biology, Species, Botany, Vegetation, Grassland, Biological classification, Hungary, Habitat fragmentation


Habenaria is a large genus of terrestrial orchids distributed throughout the tropical and subtropical regions of the world. The integrity and monophyly of this genus have been under discussion for many years, and at one time or another, several genera have been either included in a broadly defined Habenaria or segregated from it. In this study, the phylogenetic relationships of the Neotropical members of the genus and selected groups of African Habenaria were investigated using DNA sequences from the nuclear internal transcribed spacer (ITS) region and the plastid matK gene sampled from 151 taxa of Habenaria from the Neotropics (ca. 51% of the total) as well as 20 species of Habenaria and Bonatea from the Old World. Bayesian and parsimony trees were congruent with each other, and in all analyses, the Neotropical species formed a highly supported group. African species of Habenaria in sections Dolichostachyae, Podandria, Diphyllae, Ceratopetalae and Bilabrellae, and the Neotropical clade formed a highly supported “core Habenaria clade”, which includes the type species of the genus from the New World. The topology of the trees indicates an African origin for the Neotropical clade and the low sequence divergence among the Neotropical species suggests a recent radiation of the genus in the New World. Species of Bonatea and Habenaria sections Chlorinae and Multipartitae formed a well-supported clade that was sister to the “core Habenaria clade”. The Neotropical clade consists of at least 21 well-supported subgroups, but all Neotropical sections of the current sectional classification are paraphyletic or polyphyletic and will need extensive revision and recircumscription. Most of the Neotropical subgroups formed morphologically uniform assemblage of species, but some cases of morphological divergence within subgroups and convergence between subgroups indicated that morphology alone can be misleading for inferring relationships within the genus. The genera Bertauxia, Kusibabella and Habenella, segregated from New World Habenaria, are not monophyletic and a revision of the sectional classification rather than a generic division seems most appropriate. Our results do not support an extensive generic fragmentation of Habenaria as previously suggested and will provide a framework for revising the infrageneric classification and investigating the patterns of morphological evolution and geographical distribution of the genus in the New World.

Concepts: DNA, Organism, Species, Phylogenetics, Polyphyly, Binomial nomenclature, Clade, Biological classification


Structured triacylglycerols (TAGs) were isolated from nine cultivated strains of microalgae belonging to different taxonomic groups, i.e. Audouinella eugena, Balbiania investiens, Myrmecia bisecta, Nannochloropsis limnetica, Palmodictyon varium, Phaeodactylum tricornutum, Pseudochantransia sp., Thorea ramosissima, and Trachydiscus minutus. They were separated and isolated by means of NARP-LC/MS-APCI and chiral LC and the positional isomers and enantiomers of TAGs with two polyunsaturated, i.e. arachidonic (A) and eicosapentaenoic (E) acids and one saturated, i.e. palmitic acid (P) were identified. Algae that produce eicosapentaenoic acid were found to biosynthesize more asymmetrical TAGs, i.e. PPE or PEE, whereas algae which produced arachidonic acid give rise to symmetrical TAGs, i.e. PAP or APA, irrespective of their taxonomical classification. Nitrogen and phosphorus starvation consistently reversed the ratio of asymmetrical and symmetrical TAGs.

Concepts: Algae, Fatty acid, Fatty acids, Taxonomy, Ratio, Biological classification, Polyunsaturated fatty acid, Cultivated plant taxonomy