Ole Kristian Torresen

The northern dragonhead sap beetle ( Thymogethes norvegicus ) is believed to be endemic to Norway and is classified as endangered. Its life cycle is closely tied to the host plant northern dragonhead ( Dracocephalum ruyschiana ), itself classified as vulnerable in Norway. Here, we present a chromosome-level genome assembly of a male T. norvegicus . The assembly comprises two pseudo-haplotypes, hap1 and hap2, of 1,142 and 1,109 Mb, with 96.3% and 96.8% scaffolded into chromosomes, respectively. Hap1 contains 8 autosomes and the X chromosome, while hap2 contains 8 autosomes. Assembly quality was high, with conserved single-copy ortholog completeness scores of 96.6% and 90.7% and combined k-mer completeness of 98.1%. A total of 13,484 and 12,550 protein-coding genes were annotated in hap1 and hap2, respectively. This assembly provides a valuable genomic resource for the conservation of this endangered endemic species totally dependent on the vulnerable plant, the northern dragonhead.

We present a chromosome-level, haplotype-resolved genome assembly from Greenland scurvy-grass (Cochlearia groenlandica). The assembly comprises two pseudo-haplotypes of 322 Mb and 295 Mb, with 89.7% and 95.6% respectively, each scaffolded into 7 chromosomes. Assembly completeness is high (BUSCO 97.8% in each haplotype), with 34,213 and 29,684 annotated protein-coding genes for haplotypes one and two, respectively. The chromosomes contain extensive centromeric satellite arrays that cover up to half of some chromosomes. Their precise functional boundaries remain undetermined.

We describe a chromosome-level, haplotype-resolved genome assembly from a male wolverine ( Gulo gulo gulo ). The assembly comprises two pseudo-haplotypes of 2,523.2 Mb and 2,288.4 Mb, with 95.8% and 97.8% scaffolded into 20 autosomal chromosomes and sex chromosomes (placed in haplotype one). Assembly completeness is high (BUSCO 98.2% and 88.9%), with 20,337 and 17,692 annotated protein-coding genes for haplotypes one and two, respectively. Compared to existing wolverine genomes, the current genome is more complete and contains both sex chromosomes. This reference genome will be an important resource for population studies and conservation biology of this large carnivore.

We describe a chromosome-level, haplotype-resolved genome assembly from a male European moose (Alces alces alces). The assembly comprises two pseudo-haplotypes of 3,148 Mb and 3,112 Mb, with sex chromosomes in haplotype one, and 33 autosomes in each haplotype (68 in total). Assembly completeness is high (BUSCO 98.3% and 95.7%), with 21,496 and 20,498 annotated protein-coding genes for haplotypes one and two, respectively. This genome assembly is the most complete so far generated for European moose.

We present a chromosome-level genome assembly of a female great grey owl (Strix nebulosa lapponica). The assembly comprises two pseudo-haplotypes of 1,554 Mb and 1,242 Mb, with 83.2% and 91.4% scaffolded into chromosomes, respectively. Each pseudo-haplotype contains 40 autosomal chromosomes, with the Z and W sex chromosomes both placed in hap1. Conserved single-copy ortholog completeness was 99.2% for hap1 and 94.8% for hap2, with 18,493 and 17,279 annotated protein-coding genes, respectively. This genome establishes a reference for investigating genetic variation and chromosome evolution in great grey owls. Compared with the previous S. nebulosa assembly, this assembly includes both sex chromosomes, separates regions that were previously misassembled, and supports a diploid chromosome number of 2n = 82. Although larger chromosomes show broadly conserved synteny across owl assemblies, the recovery of additional conserved dot microchromosome-associated marker proteins suggests that Oxford Nanopore Technologies reads improved resolution of the smallest chromosomes relative to HiFi-based assemblies.

We present a chromosome-level genome assembly of a female Norwegian white-throated dipper ( Cinclus cinclus cinclus ) generated using Oxford Nanopore Technologies (ONT) long reads and Hi-C scaffolding. The assembly comprises two pseudo-haplotypes, hap1 (1186 Mb) and hap2 (1115 Mb), with 96.7% and 94.4% of sequences assigned to chromosome-scale scaffolds, respectively. Both pseudo-haplotypes contain 40 autosomes, with the Z and W sex chromosomes assigned to hap1. Compared with the PacBio HiFi-based C. c. gularis reference assembly bCinCin1.1.pri, which contains 38 autosomes, sequence represented as a single dot-chromosome (chr 36) is resolved into three distinct dot-chromosomes (chr 36, 39, and 40), a configuration supported by Hi-C contact patterns. BUSCO completeness was high for hap1 (99.2%) and hap2 (95.0%), with 19,003 and 17,746 predicted protein-coding genes, respectively. Compared with the HiFi-based C. c. gularis reference and HiFi-based assemblies generated from the same individual, the ONT-derived assemblies were substantially less fragmented and recovered more sequence from the smallest chromosomes. Synteny was otherwise largely conserved between subspecies. HiFi depletion increased strongly from macrochromosomes to micro- and dot-chromosomes, and HiFi-depleted regions were enriched for repeats and predicted non-B-DNA-associated features, particularly G-quadruplexes and direct repeats, whereas ONT coverage remained comparatively stable. These results show that conventional genome-wide assembly metrics can obscure substantial differences in the recovery of repeat-rich avian dot-chromosomes and highlight the value of chromosome-aware evaluation and ONT sequencing for recovering these regions.

We present the first chromosome-level reference genome for Lepidurus arcticus (Pallas, 1793), a freshwater crustacean with circumpolar distribution. L. arcticus belongs to the small order of freshwater notostracan crustaceans that are representatives of the ancient group Branchiopoda. This group has a remarkable morphological stability and is frequently labeled “living fossils.” Its ancient origin, streamlined genome and reproductive flexibility makes this a very interesting candidate for genomic studies. The pseudo-haplotype-resolved assemblies, hap1 and hap2, span 81.2 megabases (Mb) and 81.8 Mb, respectively, and were each scaffolded into six chromosomes. Both hap1 and hap2 showed high completeness, with identical conserved single-copy ortholog completeness scores of 98.3%. Scaffold N50 lengths were 13.4 Mb for hap1 and 13.9 Mb for hap2, and k-mer completeness estimated from PacBio HiFi reads was 95.79% and 96.18%, respectively. The pseudo-haplotypes showed very low estimated genome-wide heterozygosity of 0.133%. Gene annotation identified 10,901 protein-coding genes in hap1 and 10,910 in hap2. Repetitive elements comprised approximately 24% to 25% of each assembly, with long terminal repeat retrotransposons representing the most abundant transposable element class at approximately 8% to 9%. Comparison with the near chromosome-level genome of Lepidurus packardi revealed substantial intrachromosomal rearrangements, despite similar chromosome numbers and chromosome sizes. Differences in transposable element content between L. arcticus and L. packardi were primarily driven by retrotransposons, particularly long terminal repeat retrotransposons and long interspersed nuclear elements. This reference genome provides a valuable resource for future population genomic studies and for investigating evolutionary stasis at the genome level.

We describe a chromosome-level, pseudo-haplotype-resolved genome assembly from a female bluethroat (Luscinia s. svecica). The assembly comprises two pseudo-haplotypes of 1,461 and 1,171 Mb, with 77.4% and 88.4% scaffolded into 40 autosomal chromosomes and the W and Z sex chromosomes in pseudo-haplotype one. Assembly completeness is high (BUSCO 99.2% and 94.9%), with 22,462 and 18,769 annotated protein-coding genes for pseudo-haplotypes one and two, respectively. The use of Oxford Nanopore Technologies sequencing enables resolution of genomic regions that are often fragmented in genome assemblies, including the hypervariable major histocompatibility complex. We find that MHC loci include both the canonical organization of tandemly duplicated MHCIIβ genes with a single MHCIIα, and a distinct arrangement in which MHCI and MHCIIβ loci are interspersed. Substantial structural differences between the two assembled chromosome 35 homologs are resolved across the major histocompatibility complex region.

We describe a chromosome-level, haplotype-resolved genome assembly from a male European moose ( Alces alces alces ). The assembly comprises two pseudo-haplotypes of 3,148 Mb and 3,112 Mb, with sex chromosomes in haplotype one, and 33 autosomes in each haplotype (68 in total). Assembly completeness is high (BUSCO 98.3% and 95.7%), with 21,496 and 20,498 annotated protein-coding genes for haplotypes one and two, respectively. This genome assembly is the most complete so far generated for European moose.

We present a chromosome-level genome assembly of a female great grey owl ( Strix nebulosa lapponica ). The assembly comprises two pseudo-haplotypes of 1554 Mb and 1242 Mb, with 83.2% and 91.4% scaffolded into 40 autosomal chromosomes, in addition to the W and Z sex chromosomes both placed in hap1. Assembly completeness is high (BUSCO 99.2% and 94.8%), with 18,493 and 17,279 annotated protein-coding genes for hap1 and hap2, respectively. This genome establishes a reference for investigating genetic variation and chromosome evolution in great grey owls. Compared with the previous S. nebulosa assembly, this assembly includes both sex chromosomes, separates regions that were previously collapsed, and resolves 82 chromosomes total. While larger chromosomes show broadly conserved synteny across owl assemblies, the recovery of additional conserved microchromosome-associated genes suggests that ONT reads improved resolution of the smallest chromosomes relative to HiFi-based assemblies.