Ksenia Krasheninnikova

Chromosomal rearrangements reshape genome architecture, but rate variation across the tree of life remains poorly understood. Analysing 338 beetle (Coleoptera) genomes, we inferred eight ancestral linkage groups. No species retained these linkage groups, whereas the most frequent karyotypes of 10 or 11 chromosomes evolved at least 65 times through independent rearrangements. Rearrangement rates vary widely across lineages, with exceptionally high rates associated with major species radiations. Comparisons to 340 fly and 210 butterfly and moth genomes reveal the highest rates of long-term persistent rearrangements in beetles and that the beetle X chromosome traces back to the ancestor of Holometabola. We identified frequent X chromosome changes, mostly representing recent autosomal-X fusions, but no fissions. For autosomes, key rearrangement predictors include chromosome size, repeats and centromere position.

The Vertebrate Genomes Project (VGP) aims to produce complete and near-error-free reference genomes for all ∼70,000 extant vertebrate species. Organized in four phases, it progressively targets all vertebrate orders, families, genera, and eventually all species. Here we present the completion of VGP Phase I, delivering reference genomes for ∼97% of vertebrate orders, along with additional lineages within those orders, totaling 815 species and 1.6 trillion base pairs of main haplotype sequence. These genomes were assembled and annotated over an 8-year period (2018-2026) of rapid advances in genome sequencing, assembly, and annotation methods, alongside the growth of associated consortium initiatives and international collaborations. They represent some of the highest-quality vertebrate genomes currently available, and most have become the primary reference for their respective species in public databases. Comparative analyses across a subset of 579 species when we reached a threshold of 85% of orders allowed us to reconstruct the genome of the last common ancestor of all vertebrates 500 million years ago, identify diverse modes of sex chromosome evolution, reveal clade-specific three-dimensional genome architecture, discover methylated epigenetic landscapes across vertebrates, and provide a framework for studying gene and pseudogene evolution, immune loci, cancer-associated genes, and other trait-associated loci. Approximately a quarter of this subset are listed as Vulnerable to Critically Endangered by the IUCN Red List of Threatened Species, and have enabled more advanced genomic investigations of extinction risk. VGP Phase I delivers the reference backbone for vertebrate genomics, enabling discoveries that would otherwise remain out of reach across evolution, conservation, and medicine.

Diptera genome evolution is traditionally viewed through the lens of Drosophila melanogaster . To provide an unbiased picture of chromosome evolution in Diptera, we reconstructed six ancestral linkage groups (ALGs) and their rearrangements using 340 chromosome-level genome assemblies from 59 dipteran Families and two outgroups. Notably, Diptera ALGs are conserved in many Nematoceran lineages, while emergence of Brachycera coincided with four chromosomal fissions, which subsequently fused in various combinations. In Schizophora and relatives, a stable karyotype of five metacentric chromosomes and a chromosome homologous to the dot emerged that is remarkably stable with the notable exception of Drosophila, where the metacentric chromosomes became acrocentric Muller elements. Furthermore, our reconstruction reveals an ancient sex chromosome system associated with a small and gene-poor ALG that frequently fused to other chromosomes.

Background: Notothenioids are a well characterised species flock endemic to the Antarctic and an important model group for the study of genome adaptation to extreme cold. We used a new reference assembly and clade-wide comparative genomic analysis to investigate cryonotothenioid evolution and the appearance of novel functionalities linked to cold adaptation. Results: A new phased assembly of a model notothenioid, Harpagifer antarcticus, demonstrated low levels of haplotypic variability across the genome. Nevertheless, numerous insertions from multiple LINE-L2 clades were found, suggesting ongoing transposition with potential contribution to speciation. Contrary to expectations the afgp locus was highly similar between haplotypes, except for large length allelic variants of afgp genes. Analysis suggests a model for the afgp locus expansion in H. antarcticus through segmental tandem duplications involving two pairs of afgp genes at time. Syntenic reconstruction of genomes from across the clade demonstrates conserved macrosyntenic relationships and group specific chromosomal fusions of notothenioids. Quantification of genome gain and transposition rates during cryonotothenioid diversification showed a first ancestral slow genome expansion concurrent with historic temperature drops. This was followed by lineage-specific massive peaks of genomic gain and transposition activity. Finally, we identified a set of genes that underwent ancestral diversifying selection and acquired novel conserved non-coding elements during the cryonotothenioid emergence. These were related to antioxidants and proteostasis, which may have facilitated the notothenioid Antarctic radiation. Conclusion: Diversifying selection and genomic gain linked to transposon activity are primary contributors to lineage-specific evolutionary dynamics through the clade which facilitated adaptation to life in the cold.

Mustelinae are among the most diverse and taxonomically complex subfamilies within the Mustelidae, yet their evolutionary history and genetic diversity remain largely unexplored at the whole-genome level. Here, we present the first comprehensive comparative and phylogenomic study of this lineage, integrating nuclear and mitochondrial genomes from 10 species across the Holarctic and Indomalayan realms. Our dataset includes two novel genome assemblies (Mustela strigidorsa, M. sibirica) and an improved genome for M. nivalis, enabling robust cross-species analyses of genome size, chromosomal evolution, genetic diversity, and demographic history. We uncover striking inter- and intraspecific variation in genome-wide heterozygosity and genome size, with evidence of marked homozygosity in some Asian lineages (M. eversmanii, M. sibirica, M. strigidorsa) and remarkable genetic diversity in widespread species such as M. nivalis and M. erminea. Phylogenomic results support the previously suggested split of M. richardsonii from M. erminea, but we found no evidence for speciation within M. nivalis. Ancestral reconstruction of chromosomal rearrangements revealed key chromosomal fissions that shaped the Mustelinae radiation, including early events predating the divergence of modern Mustela species. The results confirmed the suggested ancestral karyotypes of Mustela (2n = 44) and Mustelinae (2n = 42). Finally, demographic reconstructions exposed species-specific responses to Quaternary climatic cycles, ranging from long-term resilience in M. nivalis to repeated population bottlenecks in M. putorius and M. sibirica. Collectively, our findings establish a genomic foundation for future evolutionary and conservation genomic research on this emblematic Mustelidae lineage.

The sable (Martes zibellina) and pine marten (Martes martes) are two Palearctic mustelids with long-recognized hybrids (kidases), whose fertility was controversial for years. Early genetic studies confirmed the existence of hybrids beyond F1, but limited marker resolution prevented detailed characterization of hybrid ancestry. Both species were hunted for centuries, but anthropogenic pressures during the 20th-century caused severe bottlenecks in the sable. Hunting bans and large-scale reintroduction programs restored sable populations across much of its range, including the sympatric zone, potentially affecting hybridization. We resequenced 30 individuals from most of the sables’ range and the Eastern part of pine marten's. Among samples, we found a broad spectrum of hybrid types with mosaic recombinant chromosomes that confirm hybrid fertility and indicate crossover is not suppressed in kidases. This necessitates re-evaluation of previous research, as we detected notable discrepancies between short tandem repeat-based ancestry and whole-genome analysis. We revealed mitochondrial DNA introgression from sables into most pine martens, indicating displacement of native pine marten mitochondrial sequences. Pine marten heterozygosity is relatively low (∼0.5 to 0.6 hetSNPs/kbp), while sable's diversity (∼1.5 to 1.8 hetSNPs/kbp) is unexpectedly high given its demographic history, likely reflecting successful reintroduction programs. We dated species divergence at 1.52 [confidence interval (CI): 1.05 to 2.06] Mya, and identified candidate genes potentially associated with hybrid fertility issues. This study is the first to elucidate marten hybridization at the whole-genome level, opening new research directions for understanding hybridization among Holarctic martens, the genetic consequences of reintroduction programs, and comparative adaptomics.

The sable ( Martes zibellina ) and pine marten ( Martes martes ) are two Palearctic mustelids with long-recognized hybrids (kidases), whose fertility was controversial for years. Early genetic studies confirmed hybrids beyond F1, but details remained unclear due to low-resolution methods. Both species were hunted for centuries, but anthropogenic pressures during the 20th-century caused severe bottlenecks in the sable followed by hunting bans and large-scale reintroduction programs across much of its range, including the sympatric zone, potentially affecting hybridization. We resequenced 30 individuals from most of the sables’ range and Eastern part of pine marten’s. Among samples, we found a broad spectrum of hybrid types with mosaic recombinant chromosomes that confirm hybrid fertility and indicate crossover is not suppressed in kidases. This necessitates re-evaluation of previous research, as we detected notable discrepancies between STR-based ancestry and whole-genome analysis. In pine martens, we revealed mitochondrial DNA introgression from sables, indicating displacement of native pine marten mitochondrial sequences. Pine marten heterozygosity is relatively low (∼0.5-0.6 hetSNPs/kbp) while sable diversity (∼1.5-1.8 hetSNPs/kbp) is unexpectedly high for a species with its demographic history, likely reflecting successful reintroduction programs. We dated species divergence at 1.52 (CI: 1.05-2.06) Mya and identified candidate genes associated with ecological, morphological, and dietary differences, as well as hybrid fertility issues. This study is the first to elucidate marten hybridization at the whole-genome level, opening new research directions for understanding hybridization among Holarctic martens, the genetic consequences of reintroduction programs, and comparative adaptomics.

Mustelinae are among the most diverse and taxonomically complex subfamilies within the Mustelidae, yet their evolutionary history and genetic diversity remain largely unexplored at the whole-genome level. Here, we present the first comprehensive comparative and phylogenomic study of this lineage, integrating nuclear and mitochondrial genomes from ten species across the Holarctic and Indomalayan realms. Our dataset includes two novel genome assemblies ( Mustela strigidorsa , M. sibirica ) and an improved genome for M. nivalis , enabling robust cross-species analyses of genome size, chromosomal evolution, genetic diversity, and demographic history. We uncover striking inter-and intraspecific variation in genome-wide heterozygosity and genome size, with evidence of marked homozygosity in some Asian lineages ( M. eversmanii , M. sibirica , M. strigidorsa ) and remarkable genetic diversity in widespread species such as M. nivalis and M. erminea . Phylogenomic results support the previously suggested split of M. richardsonii from M. erminea , but we found no evidence for speciation within M. nivalis . Ancestral reconstruction of chromosomal rearrangements revealed key chromosomal fissions that shaped the Mustelinae radiation, including early events predating the divergence of modern Mustela species. The results confirmed the ancestral karyotype of Mustela (2n=44) and the Mustelinae (2n=42). Finally, demographic reconstructions exposed species-specific responses to Quaternary climatic cycles, ranging from long-term resilience in M. nivalis to repeated population bottlenecks in M. putorius and M. sibirica . Collectively, our findings establish a genomic foundation for future evolutionary and conservation genomic research on this emblematic Mustelidae lineage.

The manuscript presents a genome assembly of Sholicola albiverntris - an avian species endemic to a restricted area in India. Authors provide a comprehensive description of the methods used for species collection, sequencing, and assembly. The prese...

Pusa sibirica, the Baikal seal, is the only extant, exclusively freshwater, pinniped species. The pending issue is, how and when they reached their current habitat—the rift lake Baikal, more than three thousand kilometers away from the Arctic Ocean. To explore the demographic history and genetic diversity of this species, we generated a de novo chromosome-length assembly, and compared it with three closely related marine pinniped species. Multiple whole genome alignment of the four species compared with their karyotypes showed high conservation of chromosomal features, except for three large inversions on chromosome VI. We found the mean heterozygosity of the studied Baikal seal individuals was relatively low (0.61 SNPs/kbp), but comparable to other analyzed pinniped samples. Demographic reconstruction of seals revealed differing trajectories, yet remarkable variations in Ne occurred during approximately the same time periods. The Baikal seal showed a significantly more severe decline relative to other species. This could be due to the difference in environmental conditions encountered by the earlier populations of Baikal seals, as ice sheets changed during glacial–interglacial cycles. We connect this period to the time of migration to Lake Baikal, which occurred ~3–0.3 Mya, after which the population stabilized, indicating balanced habitat conditions.