Arild Johnsen

Utvalgte publikasjoner

• Cramer, Emily Rebecca A; Rowe, Melissah; Eroukhmanoff, Fabrice; Lifjeld, Jan Terje; Sætre, Glenn-Peter & Johnsen, Arild (2019). Measuring sperm swimming performance in birds: effects of dilution, suspension medium, mechanical agitation, and sperm number. Journal of Ornithology = Journal fur Ornithologie.  ISSN 0021-8375.  s 1- 11 . doi: 10.1007/s10336-019-01672-9
• Lifjeld, Jan Terje; Gohli, Jostein; Albrecht, Tomas; Garcia-del-Rey, Eduardo; Johannessen, Lars Erik; Kleven, Oddmund; Marki, Petter Zahl; Omotoriogun, Taiwo Crossby; Rowe, Melissah & Johnsen, Arild (2019). Evolution of female promiscuity in Passerides songbirds. BMC Evolutionary Biology.  ISSN 1471-2148.  19(1) . doi: 10.1186/s12862-019-1493-1 Fulltekst i vitenarkiv. Vis sammendrag

  Background: Female promiscuity is highly variable among birds, and particularly among songbirds. Comparative work has identified several patterns of covariation with social, sexual, ecological and life history traits. However, it is unclear whether these patterns reflect causes or consequences of female promiscuity, or if they are byproducts of some unknown evolutionary drivers. Moreover, factors that explain promiscuity at the deep nodes in the phylogenetic tree may be different from those important at the tips, i.e. among closely related species. Here we examine the relationships between female promiscuity and a broad set of predictor variables in a comprehensive data set (N = 202 species) of Passerides songbirds, which is a highly diversified infraorder of the Passeriformes exhibiting significant variation in female promiscuity. Results: Female promiscuity was highly variable in all major clades of the Passerides phylogeny and also among closely related species. We found several significant associations with female promiscuity, albeit with fairly small effect sizes (all R2 ≤ 0.08). More promiscuous species had: 1) less male parental care, particularly during the early stages of the nesting cycle (nest building and incubation), 2) more short-term pair bonds, 3) greater degree of sexual dichromatism, primarily because females were drabber, 4) more migratory behaviour, and 5) stronger premating sexual selection. In a multivariate model, however, the effect of sexual selection disappeared, while the other four variables showed additive effects and together explained about 16% of the total variance in female promiscuity. Female promiscuity showed no relationship with body size, life history variation, latitude or cooperative breeding. Conclusions: We found that multiple traits were associated with female promiscuity, but these associations were generally weak. Some traits, such as reduced parental care in males and more cryptic plumage in females, might even be responses to, rather than causes of, variation in female promiscuity. Hence, the high variation in female promiscuity among Passerides species remains enigmatic. Female promiscuity seems to be a rapidly evolving trait that often diverges between species with similar ecologies and breeding systems. A future challenge is therefore to understand what drives within-lineage variation in female promiscuity over microevolutionary time scales. Keywords: Extrapair paternity, Life history, Mating system, Pair bond, Parental care, Sexual selection

• Støstad, Hanna Nyborg; Rowe, Melissah; Johnsen, Arild & Lifjeld, Jan Terje (2019). Sperm head abnormalities are more frequent in songbirds with more helical sperm: A possible trade-off in sperm evolution. Journal of Evolutionary Biology.  ISSN 1010-061X.  s 1- 9 . doi: 10.1111/jeb.13446
• Støstad, Hanna Nyborg; Rowe, Melissah; Johnsen, Arild; Tomasek, Oldrich; Albrecht, Tomas & Lifjeld, Jan Terje (2019). Sperm head abnormalities are associated with excessive omega-6 fatty acids in two finch species feeding on sunflower seeds. Journal of Avian Biology.  ISSN 0908-8857.  50(3), s 1- 12 . doi: 10.1111/jav.02056
• Kearns, Anna Marika; Restani, Marco; Szabo, Ildiko; Schrøder-Nielsen, Audun; Kim, Jin Ah; Richardson, Hayley M.; Marzluff, John M.; Fleischer, Robert C.; Johnsen, Arild & Omland, Kevin E. (2018). Genomic evidence of speciation reversal in ravens. Nature Communications.  ISSN 2041-1723.  9(1) . doi: 10.1038/s41467-018-03294-w Vis sammendrag

  Many species, including humans, have emerged via complex reticulate processes involving hybridisation. Under certain circumstances, hybridisation can cause distinct lineages to collapse into a single lineage with an admixed mosaic genome. Most known cases of such ‘speciation reversal’ or ‘lineage fusion’ involve recently diverged lineages and anthropogenic perturbation. Here, we show that in western North America, Common Ravens (Corvus corax) have admixed mosaic genomes formed by the fusion of non-sister lineages (‘California’ and ‘Holarctic’) that diverged ~1.5 million years ago. Phylogenomic analyses and concordant patterns of geographic structuring in mtDNA, genome-wide SNPs and nuclear introns demonstrate long-term admixture and random interbreeding between the non-sister lineages. In contrast, our genomic data support reproductive isolation between Common Ravens and Chihuahuan Ravens (C. cryptoleucus) despite extensive geographic overlap and a sister relationship between Chihuahuan Ravens and the California lineage. These data suggest that the Common Raven genome was formed by secondary lineage fusion and most likely represents a case of ancient speciation reversal that occurred without anthropogenic causes.

• Králová, Tereza; Albrecht, Tomas; Bryja, Josef; Horák, David; Johnsen, Arild; Lifjeld, Jan Terje; Novotny, Marian; Sedlacek, Ondrej; Velova, Hana & Vinkler, Michal (2018). Signatures of diversifying selection and convergence acting on passerine Toll-like receptor 4 in an evolutionary context. Molecular Ecology.  ISSN 0962-1083.  27(13), s 2871- 2883 . doi: 10.1111/mec.14724
• Magnussen, Trude; Kjærandsen, Jostein; Johnsen, Arild & Søli, Geir Einar Ellefsen (2018). Six new species of Afrotropical Allodia (Diptera: Mycetophilidae): DNA barcodes indicate recent diversification with a single origin. Zootaxa.  ISSN 1175-5326.  4407(3), s 301- 320 . doi: 10.11646/zootaxa.4407.3.1
• Rekdal, Silje Larsen; Anmarkrud, Jarl Andreas; Johnsen, Arild & Lifjeld, Jan Terje (2018). Genotyping strategy matters when analyzing hypervariable major histocompatibility complex-Experience from a passerine bird. Ecology and Evolution.  ISSN 2045-7758.  8(3), s 1680- 1692 . doi: 10.1002/ece3.3757
• Støstad, Hanna Nyborg; Johnsen, Arild; Lifjeld, Jan Terje & Rowe, Melissah (2018). Sperm head morphology is associated with sperm swimming speed: a comparative study of songbirds using electron microscopy. Evolution.  ISSN 0014-3820.  72(9), s 1918- 1932 . doi: 10.1111/evo.13555 Vis sammendrag

  Sperm exhibit extraordinary levels of morphological diversification across the animal kingdom. In songbirds, sperm have a helically shaped head incorporating a distinct acrosomal membrane or “helical keel,” the form and extent of which varies across species. The functional significance of this helical shape, however, remains unknown. Using scanning electron microscopy, we quantified inter‐ and intraspecific variation in sperm head morphology across 36 songbird species (Passeriformes: Passerida). Using phylogenetic comparative methods, we investigated the relationship between sperm head morphology and both sperm swimming speed and the frequency of extra‐pair young (EPY). We found that species whose sperm had a relatively more pronounced helical form (i.e., long acrosome, short nucleus, wide helical membrane, and a more pronounced waveform along the sperm head “core”) had faster‐swimming sperm. We found no evidence of a relationship between interspecific variation in sperm head morphology and EPY, although we did find that among‐ and within‐male variation in sperm head traits were negatively correlated with EPY. Applying principles of fluid mechanics, we discuss how the helical form of the sperm head may influence swimming speed, and suggest that further studies considering aspects of sperm morphology beyond sperm length are needed to improve our understanding of sperm structure‐function relationships.

• Sætre, Camilla Lo Cascio; Johnsen, Arild; Stensrud, Even & Cramer, Emily Rebecca A (2018). Sperm morphology, sperm motility and paternity success in the bluethroat (Luscinia svecica). PLOS ONE.  ISSN 1932-6203.  13(3) . doi: 10.1371/journal.pone.0192644
• Boumans, Louis; Hogner, Silje; Brittain, John Edward & Johnsen, Arild (2017). Ecological speciation by temporal isolation in a population of the stonefly Leuctra hippopus (Plecoptera, Leuctridae). Ecology and Evolution.  ISSN 2045-7758.  7(5), s 1635- 1649 . doi: 10.1002/ece3.2638 Vis sammendrag

  Stream dwelling invertebrates are ideal candidates for the study of ecological speciation as they are often adapted to particular environmental conditions within a stream and inhabit only certain reaches of a drainage basin, separated by unsuitable habitat. We studied an atypical population of the stonefly Leuctra hippopus at a site in central Norway, the Isterfoss rapids, in relation to three nearby and two remote conspecific populations. Adults of this population emerge about a month earlier than those of nearby populations, live on large boulders emerging from the rapids, and are short-lived. This population also has distinct morphological features and was studied earlier during the period 1975–1990. We reassessed morphological distinctness with new measurements and added several analyses of genetic distinctness based on mitochondrial and nuclear sequence markers, as well as AFLP fingerprinting and SNPs mined from RAD sequences. The Isterfoss population is shown to be most closely related to its geographical neighbors, yet clearly morphologically and genetically distinct and homogeneous. We conclude that this population is in the process of sympatric speciation, with temporal isolation being the most important direct barrier to gene flow. The shift in reproductive season results from the particular temperature and water level regime in the Isterfoss rapids. The distinct adult body shape and loss of flight are hypothesized to be an adaptation to the unusual habitat. Ecological diversification on small spatial and temporal scales is one of the likely causes of the high diversity of aquatic insects.

• Garcia, Javier; Johnsen, Arild; Fuertes, Benito & Suarez-Seoane, Susana (2017). Evolutionary divergences in Luscinia svecica subspecies complex - New evidence supporting the uniqueness of the Iberian bluethroat breeding populations. Ornis Fennica.  ISSN 0030-5685.  94(3), s 141- 149 Fulltekst i vitenarkiv.
• Johnsen, Arild; Kearns, Anna Marika; Omland, Kevin E. & Anmarkrud, Jarl Andreas (2017). Sequencing of the complete mitochondrial genome of the common raven Corvus corax (Aves: Corvidae) confirms mitogenome-wide deep lineages and a paraphyletic relationship with the Chihuahuan raven C. cryptoleucus. PLOS ONE.  ISSN 1932-6203.  12(10) . doi: 10.1371/journal.pone.0187316 Fulltekst i vitenarkiv.
• Johnsen, Arild; Pauliny, Angela; Lifjeld, Jan Terje & Blomqvist, Donald (2017). Is telomere length associated with mate choice in a songbird with a high rate of extrapair paternity?. PLOS ONE.  ISSN 1932-6203.  12(8) . doi: 10.1371/journal.pone.0182446 Fulltekst i vitenarkiv.
• Cramer, Emily Rebecca A; Stensrud, Even; Marthinsen, Gunnhild; Hogner, Silje; Johannessen, Lars Erik; Laskemoen, Terje; Eybert, Marie-Christine; Slagsvold, Tore; Lifjeld, Jan Terje & Johnsen, Arild (2016). Sperm performance in conspecific and heterospecific female fluid. Ecology and Evolution.  ISSN 2045-7758. . doi: 10.1002/ece3.1977 Fulltekst i vitenarkiv.
• Cramer, Emily Rebecca A; Ålund, Murielle; McFarlane, S. Eryn; Johnsen, Arild & Qvarnström, Anna (2016). Females discriminate against heterospecific sperm in a natural hybrid zone. Evolution.  ISSN 0014-3820.  70(8), s 1844- 1855 . doi: 10.1111/evo.12986
• Eroukhmanoff, Fabrice; Rowe, Melissah; Cramer, Emily Rebecca A; Haas, Fredrik; Hermansen, Jo Skeie; Runemark, Anna; Johnsen, Arild & Sætre, Glenn-Peter (2016). Experimental evidence for ovarian hypofunction in sparrow hybrids. Avian Research.  ISSN 2053-7166.  7 . doi: 10.1186/s40657-016-0038-1
• Lemoine, Melissa; Lucek, Kay; Perrier, Charles; Saladin, Verena; Adriaensen, Frank; Barba, Emilio; Belda, Eduardo J; Charmantier, Anne; Cichon, Mariusz; Eeva, Tapio; Gregoire, Arnaud; Hinde, Camilla A; Johnsen, Arild; Komdeur, Jan; Mänd, Raivo; Matthysen, Erik; Norte, Ana Claudia; Pitala, Natalia; Sheldon, Ben C; Slagsvold, Tore; Tinbergen, Joost M; Török, Janos; Ubels, Richard; van Oers, Kees; Visser, Marcel E; Doligez, Blandine & Richner, Heinz (2016). Low but contrasting neutral genetic differentiation shaped by winter temperature in European great tits. Biological Journal of the Linnean Society.  ISSN 0024-4066.  118(3), s 668- 685 . doi: 10.1111/bij.12745
• Lifjeld, Jan Terje; Anmarkrud, Jarl Andreas; Calabuig, Pascual; Cooper, Joseph E.J.; Johannessen, Lars Erik; Johnsen, Arild; Kearns, Anna Marika; Lachlan, Robert F.; Laskemoen, Terje; Marthinsen, Gunnhild; Stensrud, Even & Garcia-del-Rey, Eduardo (2016). Species-level divergences in multiple functional traits between the two endemic subspecies of Blue Chaffinches Fringilla teydea in Canary Islands. BMC Zoology.  ISSN 2056-3132. . doi: 10.1186/s40850-016-0008-4
• Mutanen, Marko; Kivelä, Sami M.; Vos, Rutger A.; Doorenweerd, Camiel; Ratnasingham, Sujeevan; Hausmann, Axel; Huemer, Peter; Dincă, Vlad; Van Nieukerken, Erik J.; Lopez-Vaamonde, Carlos; Vila, Roger; Aarvik, Leif; Decaëns, Thibaud; Efetov, Konstantin A.; Hebert, Paul D.N.; Johnsen, Arild; Karsholt, Ole; Pentinsaari, Mikko; Rougerie, Rodolphe; Segerer, Andreas H.; Tarmann, Gerhard; Zahiri, Reza & Godfray, H. Charles J. (2016). Species-level para- and polyphyly in DNA barcode gene trees: Strong operational bias in European Lepidoptera. Systematic Biology.  ISSN 1063-5157.  65(6), s 1024- 1040 . doi: 10.1093/sysbio/syw044
• Støstad, Hanna Nyborg; Rekdal, Silje Larsen; Kleven, Oddmund; Laskemoen, Terje; Marthinsen, Gunnhild; Johnsen, Arild & Lifjeld, Jan Terje (2016). Weak geographical structure in sperm morphology across the range of two willow warbler Phylloscopus trochilus subspecies in Scandinavia. Journal of Avian Biology.  ISSN 0908-8857.  47(5), s 731- 741 . doi: 10.1111/jav.00981 Fulltekst i vitenarkiv. Vis sammendrag

  Sperm morphology is highly diversified among species and at higher taxonomic levels. In birds, there is also increasing evidence of geographical differentiation in sperm traits within species, especially in those with strong sperm competition. Geographical divergences in sperm traits might imply the formation of a reproductive barrier in a speciation process. Here we study sperm morphology variation of willow warblers Phylloscopus trochilus in a geographical context in Scandinavia, across the range of two subspecies that are differentiated in certain genetic markers, morphology and migratory routes. We describe geographical patterns in genotypes (two previously described single-nucleotide polymorphism (SNP) markers and four polymorphic microsatellites); in wing length, tarsus length and body mass; and in sperm traits of 330 male willow warblers sampled at 33 localities across Norway (58°N–69°N). Birds were on average larger and longer-winged in the north (spp. acredula) than in the south (spp. trochilus), and showed a sigmoid change in the SNP allele frequencies and body morphology around 65°N. We found no evidence of genetic structuring in the microsatellites. There was no geographical variation in sperm traits across Norway, except that sperm heads were on average longer in the south. Sperm head length was also associated with the two SNP markers, with longer sperm heads for the southern alleles, and midpiece length was weakly associated with one of the SNP markers. Similar among-male variances in total sperm length among the 33 sampling sites indicate uniform levels of sperm competition across Norway. We conclude that sperm morphology remains a rather undifferentiated trait between the two willow warbler subspecies in Scandinavia, which is consistent with a pattern of a shallow genetic divergence. This indicates that sperm morphology is not a reproductive barrier maintaining the narrow hybrid zone.

• Boumans, Louis & Johnsen, Arild (2015). Stonefly duets: vibrational sexual mimicry can explain complex patterns. Journal of ethology.  ISSN 0289-0771.  33(2), s 87- 107 . doi: 10.1007/s10164-015-0423-y Vis sammendrag

  Stoneflies of the suborder Arctoperlaria exchange vibration signals for intersexual communication. The exchange takes the form of a duet with a male Call and female Answer. Some species and populations have three-way duets, with the male responding to the Answer with a third signal, termed Reply. We review duet descriptions of 106 species in terms of their temporal organisation and mate guarding tactics as identified by Bailey (2003), and propose a functional explanation in terms of concealment of the female for three recurrent phenomena: (1) In the case of large temporal overlap between Call and Answer, the overlapping part of the Call masks the Answer; (2) In three-way duets, the Reply mimics the female; (3) In a Call with two distinct phases, one phase mimics the female. It turns out that the Reply can be interpreted as mimicking the Answer in virtually all three-way duets. In two-way duets with a diphasic Call, the first phase typically mimics the Answer. Three-way duets with a diphasic Call are heterogeneous. Evidence for eavesdropping behaviour comes from the observation that males of the genus Zwicknia produce a Call in response to duetting sequences more often than in response to single male Call signals. We conclude with proposals for further research.

• Cramer, Emily Rebecca A; Laskemoen, Terje; Stensrud, Even; Rowe, Melissah; Haas, Fredrik; Lifjeld, Jan Terje; Sætre, Glenn-Peter & Johnsen, Arild (2015). Morphology-function relationships and repeatability in the sperm of Passer sparrows. Journal of morphology.  ISSN 0362-2525.  276(4), s 370- 377 . doi: 10.1002/jmor.20346
• Hogner, Silje; Riera, Albert Burgas; Wold, Margrethe; Lifjeld, Jan Terje & Johnsen, Arild (2015). Intergeneric hybridization between Common Redstart Phoenicurus phoenicurus and Whinchat Saxicola rubetra revealed by molecular analyses. Journal of Ornithology.  ISSN 2193-7192.  156, s 829- 836 . doi: 10.1007/s10336-015-1165-x
• Rowe, Melissah; Albrecht, Tomas; Cramer, Emily Rebecca A; Johnsen, Arild; Laskemoen, Terje; Weir, Jason T & Lifjeld, Jan Terje (2015). Postcopulatory sexual selection is associated with accelerated evolution of sperm morphology. Evolution.  ISSN 0014-3820.  69(4), s 1044- 1052 . doi: 10.1111/evo.12620
• Wojczulanis-Jakubas, K; Kilikowska, A; Harding, AMA; Jakubas, D; Karnovsky, NJ; Steen, Harald; Strøm, Hallvard; Welcker, J; Gavrilo, M; Lifjeld, Jan Terje & Johnsen, Arild (2014). Weak population genetic differentiation in the most numerous Arctic seabird, the little auk. Polar Biology.  ISSN 0722-4060.  37(5), s 621- 630 . doi: 10.1007/s00300-014-1462-5
• Anttila, K; Couturier, Christine Stephanie; Øverli, Øyvind; Johnsen, Arild; Marthinsen, Gunnhild; Nilsson, Göran Erik & Farrell, Anthony P. (2014). Atlantic salmon show capability for cardiac acclimation to warm temperatures. Nature Communications.  ISSN 2041-1723.  5 . doi: 10.1038/ncomms5252
• Boumans, Louis & Johnsen, Arild (2014). Species-specific communication bars interspecific mating between syntopic species of Zwicknia stoneflies (Plecoptera: Capniidae). Biological Journal of the Linnean Society.  ISSN 0024-4066.  113(4), s 969- 980 . doi: 10.1111/bij.12372 Vis sammendrag

  Most Northern Hemisphere stoneflies have species-specific mating signals that are generally thought to constitute a barrier against interspecific mating. We tested this hypothesis in two species of the genus Zwicknia that have only very recently been recognised as distinct species, and that were found to occur together in a stream in Lower Saxony, Germany. Analyses of molecular markers COI and 28S in combination with wing length (distinguishing males of both species) and mating signals revealed no instance of hybridisation among 23 studied specimens. In addition, eleven further males identified on the basis of morphology alone all produced the expected species-specific signal. Females and males of both species were presented with played back conspecific and heterospecific signals and duetting sequences, and responded only to conspecific stimuli. This lends support to the hypothesis that the intersexual communication system functions as an important pre-mating barrier against gene flow, although post-mating isolation cannot be excluded. Interspecific mating did occur when a mixed pair was confined together in a small container. Males of both species were found to call in response to played back duetting sequences with stereotypic latencies that are clearly longer than the latencies in male-female duets. We interpret this as an indication of eavesdropping behaviour coupled with attempts to take over the perceived duet.

• Brabrand, Åge; Bremnes, Trond; Koestler, Andreas Georg; Marthinsen, Gunnhild; Pavels, Henning; Rindal, Eirik; Raastad, Jan Emil; Saltveit, Svein Jakob & Johnsen, Arild (2014). Mass occurrence of bloodsucking blackflies in a regulated river reach: Localization of oviposition habitat of Simulium truncatum using DNA barcoding. Rivers Research and Applications: an international journal devoted to river research and management.  ISSN 1535-1459.  30(5), s 602- 608 . doi: 10.1002/rra.2669
• Cramer, Emily Rebecca A; Laskemoen, Terje; Eroukhmanoff, Fabrice; Haas, Fredrik; Hermansen, Jo Skeie; Lifjeld, Jan Terje; Rowe, Melissah; Sætre, Glenn-Peter & Johnsen, Arild (2014). Testing a post-copulatory pre-zygotic reproductive barrier in a passerine species pair. Behavioral Ecology and Sociobiology.  ISSN 0340-5443.  68(7), s 1133- 1144 . doi: 10.1007/s00265-014-1724-9
• Gohli, Jostein; Leder, Erica H.; Garcia-Del-Rey, Eduardo; Johannessen, Lars Erik; Johnsen, Arild; Laskemoen, Terje; Popp, Magnus & Lifjeld, Jan Terje (2014). The evolutionary history of Afrocanarian blue tits inferred from genomewide SNPs. Molecular Ecology.  ISSN 0962-1083.  24(1), s 180- 191 . doi: 10.1111/mec.13008
• Johnsen, Arild; Brabrand, Åge; Anmarkrud, Jarl Andreas; Bjørnstad, Gro; Pavels, Henning & Saltveit, Svein Jakob (2014). Impact of human-induced environmental changes on genetic structure and variability in Atlantic salmon, Salmo salar. Fisheries Management and Ecology.  ISSN 0969-997X.  21(1), s 32- 41 . doi: 10.1111/fme.12049
• Rukke, Bjørn Arne; Cholidis, Symira; Johnsen, Arild & Ottesen, Preben (2014). Confirming Hypoderma tarandi (Diptera: Oestridae) human ophthalmomyiasis by larval DNA barcoding. Acta Parasitologica.  ISSN 1230-2821.  59(2), s 301- 304 . doi: 10.2478/s11686-014-0242-2
• Svoboda, Ales; Marthinsen, Gunnhild; Pavel, Václav; Chutný, Bohumír; Turčoková, Lucia; Lifjeld, Jan Terje & Johnsen, Arild (2014). Die prävalenz von blutparasiten beim blaukehlchen ist verknüpft mit der unterart und dem bruthabitat. Journal of Ornithology = Journal fur Ornithologie.  ISSN 0021-8375.  156(2), s 371- 380 . doi: 10.1007/s10336-014-1134-9
• Garcia-Del-Rey, Eduardo; Marthinsen, Gunnhild; Calabuig, Pascual; Estévez, Loly; Johannessen, Lars Erik; Johnsen, Arild; Laskemoen, Terje & Lifjeld, Jan Terje (2013). Reduced genetic diversity and sperm motility in the endangered Gran Canaria Blue Chaffinch Fringilla teydea polatzeki. Journal of Ornithology = Journal fur Ornithologie.  ISSN 0021-8375.  154(3), s 761- 768 . doi: 10.1007/s10336-013-0940-9
• Gohli, Jostein; Anmarkrud, Jarl Andreas; Johnsen, Arild; Kleven, Oddmund; Borge, Thomas & Lifjeld, Jan Terje (2013). Female promicuity is positively associated with neutral and selected genetic diversity in passerine birds. Evolution.  ISSN 0014-3820.  67(5), s 1406- 1419 . doi: 10.1111/evo.12045
• Hogner, Silje; Laskemoen, Terje; Lifjeld, Jan Terje; Pavel, Vaclav; Chutny, Bob; Garcia, J; Eybert, Marie-Christine; Matsyna, E & Johnsen, Arild (2013). Rapid sperm evolution in the bluethroat (Luscinia svecica) subspecies complex. Behavioral Ecology and Sociobiology.  ISSN 0340-5443.  67(8), s 1205- 1217 . doi: 10.1007/s00265-013-1548-z
• Kvie, Kjersti Sternang; Hogner, Silje; Aarvik, Leif; Lifjeld, Jan Terje & Johnsen, Arild (2013). Deep sympatric mtDNA divergence in the autumnal moth (Epirrita autumnata. Ecology and Evolution.  ISSN 2045-7758.  3(1), s 126- 144 . doi: 10.1002/ece3.434
• Mettler, Raeann; Schaefer, H.Martin; Chernetsov, Nikita; Fiedler, Wolfgang; Hobson, Keith A; Ilieva, Mihaela; Imhof, Elisabeth; Johnsen, Arild; Renner, Swen C.; Rolshausen, Gregor; Serrano, David; Wesolowski, Tomasz & Segelbacher, Gernot (2013). Contrasting Patterns of Genetic Differentiation among Blackcaps (Sylvia atricapilla) with Divergent Migratory Orientations in Europe. PLOS ONE.  ISSN 1932-6203.  8(11) . doi: 10.1371/journal.pone.0081365
• Rowe, Melissah; Laskemoen, Terje; Johnsen, Arild & Lifjeld, Jan Terje (2013). Evolution of sperm structure and energetics in passerine birds. Proceedings of the Royal Society of London. Biological Sciences.  ISSN 0962-8452.  280(1753) . doi: 10.1098/rspb.2012.2616
• Epp, Laura; Boessenkool, Sanne; Bellemain, Eva; Haile, James; Esposito, Alfonso; Riaz, Tiayyba; Erséus, Christer; Gusarov, Vladimir; Edwards, Mary E.; Johnsen, Arild; Stenøien, Hans K.; Hassel, Kristian; Kauserud, Håvard; Yoccoz, Nigel; Bråthen, Kari Anne; Willerslev, Eske; Taberlet, Pierre; Coissac, Eric & Brochmann, Christian (2012). New environmental metabarcodes for analysing soil DNA: potential for studying past and present ecosystems. Molecular Ecology.  ISSN 0962-1083.  21(8), s 1821- 1833 . doi: 10.1111/j.1365-294X.2012.05537.x
• Hogner, Silje; Laskemoen, Terje; Lifjeld, Jan Terje; Porkert, Jiri; Kleven, Oddmund; Albayrak, Tamer; Kabasakal, Bekir & Johnsen, Arild (2012). Deep sympatric mitochondrial divergence without reproductive isolation in the common redstart Phoenicurus phoenicurus. Ecology and Evolution.  ISSN 2045-7758.  2(12), s 2974- 2988 . doi: 10.1002/ece3.398 Fulltekst i vitenarkiv. Vis sammendrag

  Mitochondrial DNA usually shows low sequence variation within and high sequence divergence among species, which makes it a useful marker for phylogenetic inference and DNA barcoding. A previous study on the common redstart (Phoenicurus phoenicurus) revealed two very different mtDNA haplogroups (5% K2P distance). This divergence is comparable to that among many sister species; however, both haplogroups coexist and interbreed in Europe today. Herein, we describe the phylogeographic pattern of these lineages and test hypotheses for how such high diversity in mtDNA has evolved. We found no evidence for mitochondrial pseudogenes confirming that both haplotypes are of mitochondrial origin. When testing for possible reproductive barriers, we found no evidence for lineage-specific assortative mating and no difference in sperm morphology, indicating that they are not examples of cryptic species, nor likely to reflect the early stages of speciation. A gene tree based on a short fragment of cytochrome c oxidase subunit 1 from the common redstart and 10 other Phoenicurus species, showed no introgression from any of the extant congenerics. However, introgression from an extinct congeneric cannot be excluded. Sequences from two nuclear introns did not show a similar differentiation into two distinct groups. Mismatch distributions indicated that the lineages have undergone similar demographic changes. Taken together, these results confirm that deeply divergent mitochondrial lineages can coexist in biological species. Sympatric mtDNA divergences are relatively rare in birds, but the fact that they occur argues against the use of threshold mtDNA divergences in species delineation. Assortative mating, mtDNA, reproductive isolation, sympatric divergence

• Hogner, Silje; Sæther, Stein Are; Borge, Thomas; Bruvik, Torbjørn; Johnsen, Arild & Sætre, Glenn-Peter (2012). Increased divergence but reduced variation on the Z chromosome relative to autosomes in Ficedula flycatchers: differential introgression or the faster-Z effect?. Ecology and Evolution.  ISSN 2045-7758.  2(2), s 379- 396 . doi: 10.1002/ece3.92 Fulltekst i vitenarkiv.
• Johnsen, Arild; Carter, Kim L.; Delhey, Kaspar; Lifjeld, Jan Terje; Robertson, Raleigh J. & Kempenaers, Bart (2012). Laying-order effects on sperm numbers and on paternity: comparing three passerine birds with different life histories. Behavioral Ecology and Sociobiology.  ISSN 0340-5443.  66(2), s 181- 190 . doi: 10.1007/s00265-011-1265-4
• Heubeck, M.; Aarvak, Tomas; Isaksen, Kjell; Johnsen, Arild; Petersen, Ib Krag & Anker-Nilssen, Tycho (2011). Mass mortality of adult Razorbills Alca torda in the Skagerrak and North Sea area, autumn 2007. Seabird.  ISSN 0267-9310.  24, s 11- 32 Vis sammendrag

  An abnormal movement of auks occurred in the eastern Skagerrak in the third week of September 2007. Large numbers of Razorbills Alca torda were reported along the coasts of southeast Norway and western Sweden, many thousands entered Oslofjorden (Norway), and their migration past the northern tip of Denmark into the Kattegat began a month earlier than normal. This preceded heavy mortality of the species that lasted several weeks, and numbered thousands of individuals. Unusually for the time of year, Razorbills greatly outnumbered Common Guillemots Uria aalge in reports of live and dead birds. Of 376 Razorbills collected in Oslofjorden, 87% were adults, 9% immatures, and 4% juveniles. Among 326 adults, females (71%) outnumbered males, and 18% showed two white inner bill grooves instead of the normal one. All birds were extremely emaciated and had presumably starved to death. Virtually all adults and older immatures were still regrowing their outer primaries after the post-breeding moult, whereas those of juveniles were fully grown. Most, if not all, belonged to A. t. islandica populations breeding in the British Isles, Faroes or Iceland, and few, if any, were from A. t. torda populations of the Baltic, Norway or Russia; the 23 ringed birds found in the Skagerrak and Kattegat, mostly adults, all came from Scottish colonies. Population effects at these colonies were not obvious, but adult survival in 2007–08 was low at one colony in eastern Scotland. Long-term beached bird data indicated that while not on the scale of that in the Skagerrak and Kattegat, Razorbill mortality was abnormally high over a wide area of the North Sea in autumn 2007. The age and sex structure of the mortality and its possible causes are discussed

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• Ekrem, Torbjørn; Alsos, Inger Greve; Johnsen, Arild; Willassen, Endre; Aspaas, Aina Mærk; Merkel, Marie Kristine Føreid; Kongshavn, Katrine & Marthinsen, Gunnhild (2019). Five years as national research infrastructure: status of the Norwegian Barcode of Life Network (NorBOL).
• Ekrem, Torbjørn; Alsos, Inger Greve; Johnsen, Arild; Willassen, Endre; Aspaas, Aina Mærk; Merkel, Marie Kristine Føreid; Kongshavn, Katrine & Marthinsen, Gunnhild (2019). Five years as national research infrastructure: status of the Norwegian Barcode of Life Network (NorBOL). Genome.  ISSN 0831-2796.  62(6), s 369 . doi: 10.1139/gen-2019-0083
• Johnsen, Arild & Gjesdal, Trine-Lise (2018, 07. august). Møt en forsker: zoolog Arild Johnsen. [Tidsskrift].  Nysgjerrigper.
• Torgersen, Eivind & Johnsen, Arild (2018, 02. mars). To ravner er blitt én. [Internett].  Forskning.no.
• Ekrem, Torbjørn; Alsos, Inger Greve; Johnsen, Arild; Willassen, Endre; Aspaas, Aina Mærk; Kongshavn, Katrine; Merkel, Marie Kristine Føreid & Marthinsen, Gunnhild (2017). The Norwegian Barcode of Life Network (NorBOL).
• Ekrem, Torbjørn; Alsos, Inger Greve; Johnsen, Arild; Willassen, Endre; Aspaas, Aina Mærk; Merkel, Marie Kristine Føreid; Kongshavn, Katrine; Marthinsen, Gunnhild & Pitelkova, Iva (2017). Progress and prospects of the Norwegian Barcode of Life Network (NorBOL).
• Ekrem, Torbjørn; Alsos, Inger Greve; Johnsen, Arild; Willassen, Endre; Aspaas, Aina Mærk; Merkel, Marie Kristine Føreid; Kongshavn, Katrine; Marthinsen, Gunnhild & Pitelkova, Iva (2017). Progress and prospects of the Norwegian Barcode of Life Network (NorBOL). Genome.  ISSN 0831-2796.  60(11), s 930- 930 . doi: 10.1139/gen-2017-0209
• Johnsen, Arild (2017). Cryptic female choice at the intra- and interspecific level in passerines: what are the molecular mechanisms?.
• Johnsen, Arild (2017). DNA barcoding at NHM. Science and application.
• Johnsen, Arild (2017). Speciation reversal in ravens.
• Johnsen, Arild (2017). Sperm competition in birds: from individual to sperm behaviour.
• Johnsen, Arild (2017). Utroskap, sjalusi og spermier hos småfugl.
• Johnsen, Arild (2017). Øvre Heimdalen field station. Summary and future prospects.
• Magnussen, Trude; Søli, Geir Einar Ellefsen; Johnsen, Arild & Kjærandsen, Jostein (2017). DNA barcode libraries - A treasure chest for alpha taxonomy.
• Marthinsen, Gunnhild; Bendiksby, Mika; Brandrud, Tor Erik; Dima, Bálint; Hansen, Lars Ove; Johnsen, Arild; Lindemann, Jon Peder & Timdal, Einar (2017). Discordance between morphology and DNA barcodes in lichens, fungi and insects.
• Ålund, Murielle; Cramer, Emily Rebecca A; McFarlane, Eryn; Johnsen, Arild & Qvarnström, Anna (2017). Females discriminate against heterospecific sperm in a natural hybrid zone.
• Ekrem, Torbjørn; Alsos, Inger Greve; Johnsen, Arild; Willassen, Endre; Aspaas, Aina Mærk; Merkel, Marie Kristine Føreid; Kongshavn, Katrine; Marthinsen, Gunnhild & Stur, Elisabeth (2016). The Norwegian Barcode of Life Network (NorBOL).
• Johnsen, Arild (2016). Heimdalen: Bird research and future prospects.
• Johnsen, Arild (2016, 07. mai). Nå kommer fuglene - møt eksperten og entusiasten. [Radio].  NRK P2 - Ekko helg.
• Johnsen, Arild & Danielsen, Dag Inge (2016, 26. september). Utroskap blant fluesnappere gir færre hybridfugler. [Internett].  Forskning.no.
• Johnsen, Arild & Rekdal, Silje Larsen (2016, 08. november). Drifter. [TV].  NRK - Ut i naturen.
• Cramer, Emily Rebecca A; Ålund, Murielle; McFarlane, S. Eryn; Johnsen, Arild & Qvarnström, Anna (2015). A post-copulatory pre-zygotic barrier between collared and pied flycatchers.
• Ekrem, Torbjørn; Alsos, Inger Greve; Johnsen, Arild; Willassen, Endre; Aspaas, Aina Mærk; Føreid, Marie Kristine; Kongshavn, Katrine & Marthinsen, Gunnhild (2015). The Norwegian Barcode of Life Network (NorBOL). Vis sammendrag

  Background: NorBOL (www.norbol.org) was formed in 2007 as a national network to (i) advance barcoding of Norwegian and Arctic biodiversity, (ii) raise funding, (iii) curate barcode reference material, (iv) coordinate and initiate new barcoding projects, and (v) increase public awareness of DNA barcoding and barcoding results in Norway. NorBOL is a regional node within iBOL, with a particular responsibility for Polar Regions. NorBOL is coordinated by the NTNU University Museum in Trondheim and connects 16 institutions, including all four major natural history museums as well as all major research institutes in Norway. Results: Despite strong support among research institutions, substantial external funding was only first achieved in 2012 through a grant from the Norwegian Biodiversity Information Centre. Further funding was obtained in 2014 from both the Research Council of Norway and the Norwegian Biodiversity Information Centre. Since then, barcoding progress of the Norwegian fauna, flora, and fungi has increased, and the Barcode of Life Data Systems database currently holds more than 42 000 published sequence records (27 000 DNA barcodes) of more than 7200 species from Norway. Significance: The goal for NorBOL is to barcode 20 000 species by the end of 2018. NorBOL currently targets barcoding of museum collections, lichens, fungi, marine invertebrates, fish, and material from biosurveillance projects supported by the Norwegian Taxonomy Initiative. We collaborate with Swedish institutions on sampling of marine invertebrates, earthworms, and insects. An expansion of inter-Scandinavian barcoding collaboration is in progress. As the standard barcode gene regions have limited taxonomic resolution for the species level in many vascular plant groups, we are engaged in testing if low-coverage shotgun sequencing of herbarium material is useful to obtain the full plant plastid genomes.

• Ekrem, Torbjørn; Alsos, Inger Greve; Johnsen, Arild; Willassen, Endre; Aspaas, Aina Mærk; Føreid, Marie Kristine; Kongshavn, Katrine & Marthinsen, Gunnhild (2015). The Norwegian Barcode of Life Network (NorBOL). Genome.  ISSN 0831-2796.  58(5) Vis sammendrag

  Background: NorBOL (www.norbol.org) was formed in 2007 as a national network to (i) advance barcoding of Norwegian and Arctic biodiversity, (ii) raise funding, (iii) curate barcode reference material, (iv) coordinate and initiate new barcoding projects, and (v) increase public awareness of DNA barcoding and barcoding results in Norway. NorBOL is a regional node within iBOL, with a particular responsibility for Polar Regions. NorBOL is coordinated by the NTNU University Museum in Trondheim and connects 16 institutions, including all four major natural history museums as well as all major research institutes in Norway. Results: Despite strong support among research institutions, substantial external funding was only first achieved in 2012 through a grant from the Norwegian Biodiversity Information Centre. Further funding was obtained in 2014 from both the Research Council of Norway and the Norwegian Biodiversity Information Centre. Since then, barcoding progress of the Norwegian fauna, flora, and fungi has increased, and the Barcode of Life Data Systems database currently holds more than 42 000 published sequence records (27 000 DNA barcodes) of more than 7200 species from Norway. Significance: The goal for NorBOL is to barcode 20 000 species by the end of 2018. NorBOL currently targets barcoding of museum collections, lichens, fungi, marine invertebrates, fish, and material from biosurveillance projects supported by the Norwegian Taxonomy Initiative. We collaborate with Swedish institutions on sampling of marine invertebrates, earthworms, and insects. An expansion of inter-Scandinavian barcoding collaboration is in progress. As the standard barcode gene regions have limited taxonomic resolution for the species level in many vascular plant groups, we are engaged in testing if low-coverage shotgun sequencing of herbarium material is useful to obtain the full plant plastid genomes.

• Johnsen, Arild (2015). The early stages of the speciation process - prezygotic reproductive isolation and diversification in passerines: final report.
• Johnsen, Arild (2015). Using genetic resources in biosystematic research: examples from the NHMO DNA bank.
• Kearns, Anna Marika; Restani, Marco; Szabo, Ildiko; Fleischer, Robert; Johnsen, Arild & Omland, Kevin E. (2015). Speciation reversal in ravens? Evidence for the collapse of cryptic Old World and New World lineages.
• Omland, Kevin E.; Kearns, Anna Marika; Restani, Marco; Szabo, Ildiko & Johnsen, Arild (2015). Speciation reversal in Common Ravens: Genomic evidence of the collapse of cryptic lineages in western North America.
• Boumans, Louis; Brittain, John Edward; Johnsen, Arild & Hogner, Silje (2014). Ecological speciation by temporal isolation in a population of the stonefly Leuctra hippopus (Plecoptera, Leuctridae).
• Cramer, Emily Rebecca A; Ålund, Murielle; Laskemoen, Terje; Eroukhmanoff, Fabrice; Eybert, Marie-Christine; Haas, Fredrik; Hermansen, Jo Skeie; Lifjeld, Jan Terje; Rowe, Melissah; Qvarnström, Anna; Sætre, Glenn-Peter & Johnsen, Arild (2014). Post-copulatory, pre-zygotic isolating barriers in passerine birds?.
• Ekrem, Torbjørn; Alsos, Inger Greve; Johnsen, Arild; Willassen, Endre; Aspaas, Aina Mærk; Føreid, Marie Kristine; Kongshavn, Katrine & Marthinsen, Gunnhild (2014). Norwegian Barcode of Life.
• Ekrem, Torbjørn; Alsos, Inger Greve; Johnsen, Arild; Willassen, Endre; Aspaas, Aina Mærk; Føreid, Marie Kristine; Kongshavn, Katrine & Marthinsen, Gunnhild (2014). The Norwegian Barcode of Life Network (NorBOL). Vis sammendrag

  NorBOL (www.norbol.org) was formed in 2007 as a national network to 1) advance barcoding of Norwegian and Arctic biodiversity, 2) raise funding, 3) curate barcode reference material, 4) coordinate and initiate new barcoding projects, and 5) increase public awareness of DNA barcoding and barcoding results in Norway. NorBOL is a regional node within iBOL, with a particular responsibility for Polar Regions. NorBOL is coordinated by the NTNU University Museum in Trondheim and connects 16 institutions, including all four major natural history museums as well as all major research institutes in Norway. Despite strong support among research institutions, substantial external funding was only first achieved in 2012 through a grant from the Norwegian Biodiversity Information Centre. Further funding was obtained in 2014 from both the Research Council of Norway and the Norwegian Biodiversity Information Centre. Since then, barcoding progress of the Norwegian fauna, flora and fungi has increased and the Barcode of Life Data Systems database currently holds more than 30 000 DNA barcodes of more than 5000 species from Norway. The goal for NorBOL is to barcode 20,000 species by the end of 2018. NorBOL currently targets barcoding of museum collections, lichens, fungi, coastal marine invertebrates, and material from biosurveillance projects supported by the Norwegian Taxonomy Initiative. Collaboration with Swedish institutions on sampling of marine invertebrates for barcoding was initiated in 2006 and on earthworms in 2010. An expansion of inter-Scandinavian barcoding collaboration is in progress.

• Johnsen, Arild (2014, 26. mars). Homofile dyr og kjipe ender. [Radio].  Radiokompaniet, P4.
• Johnsen, Arild (2014, 31. mars). Hvilken fugl har seg mest?. [Radio].  Radiokompaniet, P4.
• Johnsen, Arild (2014, 06. mai). Hvorfor er vi så fascinert av fugler?. [Radio].  Ekko, NRK P2.
• Johnsen, Arild (2014, 12. februar). Sexus, hvorfor er vi hunn og hann? Om sex i evolusjonen. [Radio].  Ekko, NRK P2.
• Johnsen, Arild; Cramer, Emily Rebecca A & Grydeland, Ivar (2014, 20. august). Fugleforskerne i Heimdalen. [Radio].  Ekko, NRK P2.
• Johnsen, Arild & Graver, Gjermund (2014). Første blekbrynsanger for Akershus bekreftet ved hjelp av DNA-strekkoding. Toppdykker'n.  ISSN 0333-1687.  37(2), s 64- 67
• Kearns, Anna Marika; Johnsen, Arild; Szabo, Ildiko; Kim, Jin; Richardson, Hayley; Gobbert, Matthias; Fleischer, Robert; Restani, Marco & Omland, Kevin E. (2014). Deep Mitochondrial Divergence Within Common Ravens: Speciation Reversal in Western North America?.
• Rowe, Melissah; Albrecht, Tomas; Cramer, Emily Rebecca A; Johnsen, Arild; Laskemoen, Terje; Weir, Jason T & Lifjeld, Jan Terje (2014). Postcopulatory sexual selection accelerates rates of evolutionary divergence in sperm morphology..
• Cramer, Emily Rebecca A & Johnsen, Arild (2013). Post-mating, pre-zygotic barriers and speciation.
• Cramer, Emily Rebecca A; Laskemoen, Terje; Eroukhmanoff, Fabrice; Haas, Fredrik; Hermansen, Jo Skeie; Lifjeld, Jan Terje; Rowe, Melissah; Sætre, Glenn-Peter & Johnsen, Arild (2013). An experimental test of a potential post-copulatory pre-zygotic reproductive barrier in a passerine species pair.
• Cramer, Emily Rebecca A; Laskemoen, Terje; Eroukhmanoff, Fabrice; Haas, Fredrik; Hermansen, Jo Skeie; Lifjeld, Jan Terje; Rowe, Melissah; Sætre, Glenn-Peter & Johnsen, Arild (2013). Testing a post-copulatory pre-zygotic reproductive barrier in a passerine species pair.
• Ekrem, Torbjørn; Alsos, Inger Greve; Johnsen, Arild; Willassen, Endre; Stur, Elisabeth; Marthinsen, Gunnhild; Kirchhefer, Andreas J; Kongshavn, Katrine; Aspaas, Aina Mærk; Boström, Erik & Lin, Xiaolong (2013). The Norwegian Barcode of Life.
• Gohli, Jostein; Johnsen, Arild; Popp, Magnus; Leder, Erica H. & Lifjeld, Jan Terje (2013). Resolving species trees and rewriting taxonomy: Using next-gen sequencing data to unravel a recent radiation of a passerine bird on an island system.
• Johnsen, Arild (2013). Naturens mangfold. Om arter og hvordan de blir til.
• Kristin, Grydeland & Johnsen, Arild (2013, 03. september). Parforhold hos fugler. [Radio].  Radio Nova.
• Lifjeld, Jan Terje; Gohli, Jostein & Johnsen, Arild (2013). Promisquity, sexual selection, and genetic diversity : a reply to Spurgin. Evolution.  ISSN 0014-3820.  67(10), s 3073- 3074 . doi: 10.1111/evo.12211
• Boumans, Louis; Brittain, John Edward & Johnsen, Arild (2012). DNA barcoding of Norwegian stoneflies and heptageniid mayflies.
• Boumans, Louis; Johnsen, Arild & Brittain, John Edward (2012). DNA barcoding of Norwegian stoneflies and hepatageniid mayflies.
• Johnsen, Arild (2012). The early stages of the speciation process - prezygotic reproductive isolation and diversification in passerines.
• Johnsen, Arild (2012). The early stages of the speciation process - prezygotic reproductive isolation and diversification in passerines.
• Johnsen, Arild & Aas, Christian Kierulf (2012). Using DNA barcoding to identify birdstrike remains in Norway.
• Johnsen, Arild (2011). Barcoding – framtidas verktøy for identifisering av arter? Hvilken rolle vil museenes samlinger spille i framtida?.
• Johnsen, Arild (2011). Kan livet strekkodes?.

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