Robin Aasegg Araya

• Araya, Robin Aasegg; Maurstad, Marius Filomeno; Wilson, David T; Rash, Lachlan D; Mobli, Mehdi & Jakobsen, Kjetill Sigurd [Show all 7 contributors for this article] (2026). Ancient origin and dynamic evolution of bivalent spider toxins. Molecular Biology and Evolution (MBE). ISSN 0737-4038. 43(5). doi: 10.1093/molbev/msag076. Full text in Research Archive Show summary

  Bivalent peptide toxins comprising 2 cysteine-rich domains have evolved from single-domain precursors on multiple occasions in animal venoms, resulting in enhanced molecular target selectivity and avidity. Although bivalent toxins are emerging as prevalent in animal venoms, the genomic and evolutionary processes driving the transitions between single- and multi-domain architectures remain poorly understood. Here, we investigated the evolution of bivalent inhibitor cystine knot (ICK) toxins in spider venom. We first generated a genome assembly of the tree-dwelling funnel-web spider Hadronyche cerberea, revealing a massive expansion of ICK toxin-encoding genes, including the bivalent π-hexatoxin-Hc1a. All ICK toxin genes share a conserved 3-exon structure, flanked by transposable elements (TEs) that may have facilitated gene expansion. This gene structure is shared by the Hc1a subfamily, where the entire mature bivalent toxin is encoded by the third exon. Leveraging de novo transcriptome assemblies from 86 spider species along with venom proteomic data, we show that bivalency in the Hc1a subfamily is of ancient origin and evolved via intra-exonic duplication not involving introns. This was followed by domain expansion and recurrent domain losses mediated by point mutations, deletions, and unequal crossing-over facilitated by high interdomain sequence similarity. In contrast, the bivalent toxin DkTx from Cyriopagopus schmidti is confined to a small group of tarantulas, where it appears to have evolved once, with subsequent domain losses potentially linked to TE activity. Our findings reveal that singular events of domain duplication can give rise to complex, asymmetrical evolutionary trajectories shaped by gene instability and selective retention of functional domains.

• Hoff, Siv Nam Khang; Maurstad, Marius Filomeno; Tørresen, Ole K.; Araya, Robin Aasegg; Berg, Paul R. & Præbel, Kim [Show all 8 contributors for this article] (2026). Rapid genome modifications including chromosomal fusions and large-scale inversions are key features in Arctic codfish species. Genome Biology. ISSN 1474-7596. 27. doi: 10.1186/s13059-026-03975-6. Full text in Research Archive Show summary

  Genome evolvability involves activation of transposable elements (TEs) that result in novel genomic rearrangements, including translocations, deletions, duplications, as well as larger structural reorganizations, such as chromosomal inversions and fusions. These genomic modifications contribute to raw genetic variability in which selection can act upon, and thus, promote local adaptation. Results Using a comparative genomics framework combined with the generation of six chromosome-level gadid reference genomes, including the cold-water adapted polar cod ( Boreogadus saida ) and Arctic cod ( Arctogadus glacialis ), we uncover an array of larger and smaller chromosomal reorganizations within this lineage. For the two Arctic codfishes, we detect lineage-specific chromosomal fusions, i.e., five in polar cod vs. eight in Arctic cod, resulting in a reduced number of chromosomes found to be associated with their geographical distribution. For the same species, we identify a high number of partly overlapping chromosomal inversions where a majority (especially within breakpoint regions) display an overrepresentation of specific TE families, accompanied by signatures of high degree of conservation. We further demonstrate involvement of miniature inverted-repeat transposable elements (MITEs) in the expansion of the well-known antifreeze glycoprotein genes in polar cod, and that the three gene clusters were localized in association with chromosomal rearrangements on chromosomes 1, 2, and 14. Conclusions We characterize how the Gadidae lineage has undergone massive genomic modifications — potentially via activation of TEs — throughout their evolutionary history, and particularly for the more Arctic species. These genomic reorganizations have likely played an important role in divergence processes and adaptation to freezing environmental conditions.

• Isaksen, Anders; Nachtigall, Pedro Gabriel; Araya, Robin Aasegg; Beh, Jia Hao; Robinson, Samuel D. & Hansen, Thomas Fredrik [Show all 7 contributors for this article] (2025). Genome of the green-head ant, Rhytidoponera metallica, reveals mechanisms of toxin evolution in a genetically hyper-diverse eusocial species. Genome Biology. ISSN 1474-7596. 26(1). doi: 10.1186/s13059-025-03777-2. Full text in Research Archive Show summary

  Background While ants are textbook examples of eusocial animals in which altruistic behavior is maintained through kin selection, several ants form genetically diverse colonies that challenge this concept. One example is the Australian green-head ant (Rhytidoponera metallica) whose colonies harbor such extreme genetic variation that they have been speculated to represent an unstable form of eusociality. Yet, R. metallica is among the most successful ants on the Australian subcontinent. This success has been hypothesized to be partly due to the diverse venoms harbored within each colony. However, the genomic basis and evolutionary scenarios that maintain this toxin diversity remain unknown. Results To examine toxin genomic architecture, quantify individual-level genetic variation, and identify both proximate and ultimate mechanisms that have facilitated the toxin diversity in R. metallica, we generate a high-quality draft genome from a single worker. Most ectatotoxin genes are in clusters that contain evidence of multiple, complex gene-family expansions, some of which are likely explained by the presence of transposable elements. We also show that toxin regions of the genome exhibit elevated genetic variation despite being under strong selection and that this variation can translate to phenotypic diversity through toxin alleles with different functional properties. Conclusions Taken together, our results point to classical gene duplication and diversification as the main evolutionary mechanism by which the main toxin family in ant venoms evolves, suggest toxin-gene functional diversification under frequency-dependent selection maintains colony-level venom hypervariability in R. metallica, and provide new insight into the role of multi-level selection in eusocial animals.

• Araya, Robin Aasegg; Reinar, William Brynildsen; Tørresen, Ole K; Goubert, Clément; Daughton, Tara Jane & Hoff, Siv Nam Khang [Show all 12 contributors for this article] (2025). Chromosomal Inversions Mediated by Tandem Insertions of Transposable Elements. Genome Biology and Evolution (GBE). 17(8). doi: 10.1093/gbe/evaf131. Full text in Research Archive Show summary

  Chromosomal inversions play a crucial role in evolution by influencing phenotypes through the linkage of coadapted alleles. While inversions have been found across a large number of taxa, mapping and characterizing inversion breakpoint regions remain challenging, often due to the presence of complex tandem repeats and transposable elements. Here, we identify and quantify transposable elements in the breakpoints of the four large-scale inversions previously reported in Atlantic cod, leveraging on three high-quality long-read-based reference genome assemblies for the Norwegian Coastal cod, the Northeast Arctic cod, and Celtic cod ecotypes. We detected a significant enrichment of transposable element orders and superfamilies with terminal inverted repeats within the inversion breakpoint regions of chromosomes 1, 7 and 12. Notably, we discovered a tandem accumulation of miniature inverted-repeat transposable elements belonging to a family of hAT transposons, exclusively residing in the breakpoints of the inverted haplotype on chromosomes 1 and 7 found in the Northeast Arctic cod. The accumulation of tandemly arranged transposable elements with high sequence similarity in breakpoint regions suggests that they have driven the appearance of inversions through ectopic recombination, further supporting the potential of transposable elements in facilitating chromosomal reorganizations with large evolutionary implications.

• Araya, Robin Aasegg; Tauqeer, Fatima; Ceulemans, Michael; Gerbier, Eva; Maisonneuve, Emeline & Passier, Anneke [Show all 10 contributors for this article] (2023). Pregnancy- and Birth-Related Experiences among Postpartum Women during the Third Wave of the COVID-19 Pandemic—A Multinational European Study. Pharmacoepidemiology. 2(1), p. 54–67. doi: 10.3390/pharma2010006. Full text in Research Archive Show summary

  The objective of this study was to describe pregnancy- and birth-related experiences of postpartum women during the third wave of the COVID-19 pandemic and their association with mental health outcomes. An online questionnaire was distributed in five European countries (Belgium, The Netherlands, Norway, Switzerland, UK) between June and August 2021. Participants were recruited though socialmedia platforms including pregnancy- and motherhood-related websites, pregnancy fora, and apps. Postpartum women were asked eleven specific questions about pregnancyand birth-related changes and the presence of support during delivery. The Edinburgh Depression Scale was used to assess depressive and anxiety symptoms. Covariates included sociodemographics, health and reproductive characteristics, and COVID-19 status. Associations were estimated with logistic regression. The study included 1730 postpartum women. Frequent changes included the exclusion of the partner from pregnancy care appointments (83.2%), changed prenatal care settings (64.4%), and cancellation of hospital information visits (42.7%). Few women, however, were without support apart from medical staff during delivery (1.4%). The number of pregnancy- and birth-related changes was associated with each woman’s mental health status, as well as the type of change. Experiencing changes related to delivery and cancellation or reduction of prenatal examination was associated with a doubling in the odds of symptoms of major depression and anxiety postpartum. These findings highlight the importance of ensuring adequate maternity care for women’s mental health postpartum, as well as during a pandemic.

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