Molecular Biology and Evolution

Aneuploidy is common in eukaryotes, often leading to decreased fitness. However, evidence from fungi and human tumur cells suggests that specific aneuploidies can be beneficial under stressful conditions and facilitate adaptation. In a previous evolutionary experiment with yeast, populations evolving under heat stress became aneuploid, only to later revert to euploidy after beneficial mutations accumulated. It was therefore suggested that aneuploidy is a "stepping stone" on the path to adaptation. Here, we test this hypothesis...

Polyploidy, a significant catalyst for speciation and evolutionary processes in both plant and animal kingdoms, has been recognized for a long time. However, the exact molecular mechanism that leads to polyploid formation, especially in vertebrates, is not fully understood. Our study aimed to elucidate this phenomenon using the zebrafish model. We successfully achieved an effective knockout of the cyclin N-terminal domain containing 1 (cntd1) using CRISPR/Cas9 technology. This resulted in impaired formation of meiotic crossovers, leading to cell-cycle arrest during meiotic metaphase and triggering apoptosis of spermatocytes in the testes...

Errors in protein translation can lead to non-genetic, phenotypic mutations, including amino acid misincorporations. While phenotypic mutations can increase protein diversity, the systematic characterization of their proteome-wide frequencies and their evolutionary impact has been lacking. Here, we developed a mechanistic model of translation errors to investigate how selection acts on protein populations produced by amino acid misincorporations. We fitted the model to empirical observations of misincorporations obtained from over a hundred mass spectrometry datasets of E...

Siderophores are crucial for iron-scavenging in microorganisms. While many yeasts can uptake siderophores produced by other organisms, they are typically unable to synthesize siderophores themselves. In contrast, Wickerhamiella/Starmerella (W/S) clade yeasts gained the capacity to make the siderophore enterobactin following the remarkable horizontal acquisition of a bacterial operon enabling enterobactin synthesis. Yet, how these yeasts absorb the iron bound by enterobactin remains unresolved. Here, we demonstrate that Enb1 is the key enterobactin importer in the W/S-clade species Starmerella bombicola...

Evolutionary epigenomics and, more generally, evolutionary functional-genomics, are emerging fields that study how non-DNA-encoded alterations in gene expression regulation are an important form of plasticity and adaptation. Previous evidence analysing plants' comparative functional genomics has mostly focused on comparing same assay-matched experiments, missing the power of heterogeneous datasets for conservation inference. To fill this gap, we developed PlantFUN(ctional)CO(nservation) database, which is constituted by several tools and two main resources: inter-species chromatin states and functional genomics conservation scores, presented and analysed in this work for three well-established plant models (Arabidopsis thaliana, Oryza sativa and Zea mays)...

Hypolimnas misippus is a Batesian mimic of the toxic African Queen butterfly (Danaus chrysippus). Female H. misippus butterflies use two major wing patterning loci (M and A) to imitate three colour morphs of D. chrysippus found in different regions of Africa. In this study, we examine the evolution of the M locus and identify it as an example of adaptive atavism. This phenomenon involves a morphological reversion to an ancestral character that results in an adaptive phenotype. We show that H. misippus has re-evolved an ancestral wing pattern present in other Hypolimnas species, repurposing it for Batesian mimicry of a D...

The glacial cycles of the Quaternary heavily impacted species through successions of population contractions and expansions. Similarly, populations have been intensely shaped by human pressures such as unregulated hunting and land use changes. White-tailed and mule deer survived in different refugia through the Last Glacial Maximum, and their populations were severely reduced after the European colonisation. Here, we analysed 73 re-sequenced deer genomes from across their North American range to understand the consequences of climatic and anthropogenic pressures on deer demographic and adaptive history...

Viruses represent a major threat for all animals, which defend themselves through induction of a large set of virus-stimulated genes that collectively control the infection. In vertebrates, these genes include interferons that play a critical role in the amplification of the response to infection. Virus- and interferon-stimulated genes include restriction factors targeting the different steps of the viral replication cycle, in addition to molecules associated with inflammation and adaptive immunity. Predictably, antiviral genes evolve dynamically in response to viral pressure...

Cis-regulatory elements (CREs) have an important role in human adaptation to the living environment. However, the lag in population genomic cohort studies and epigenomic studies, hinders the research in the adaptive analysis of CREs in human populations. In this study, we collected 4,013 unrelated individuals and performed a comprehensive analysis of adaptive selection of genome-wide CREs in the Han Chinese. In total, 12.34% of genomic regions are under the influence of adaptive selection, where 1.00% of enhancers and 2...

In mammalian research, it has been debated what can initiate an evolutionary trade-off between different senses, and the phenomenon of sensory trade-off in rodents, the most abundant mammalian clade, is not evident. The Nile rat (Arvicanthis niloticus), a murid rodent, recently adapted to a diurnal niche through an evolutionary acquisition of daylight vision with enhanced visual acuity. As such, this model provides an opportunity for a cross-species investigation where comparative morphological and multi-omic analyses of the Nile rat are made with its closely related nocturnal species, e...

The blue whale, Balaenoptera musculus, is the largest animal known to have ever existed, making it an important case study in longevity and resistance to cancer. To further this and other blue whale-related research, we report a reference-quality, long-read-based genome assembly of this fascinating species. We assembled the genome from PacBio long reads and utilized Illumina/10X, optical maps, and Hi-C data for scaffolding, polishing, and manual curation. We also provided long read RNA-seq data to facilitate the annotation of the assembly by NCBI and Ensembl...

Mutation is the ultimate source of genetic variation, the bedrock of evolution. Yet, predicting the consequences of new mutations remains a challenge in biology. Gene expression provides a potential link between a genotype and its phenotype. But the variation in gene expression created by de novo mutation and the fitness consequences of mutational changes to expression remain relatively unexplored. Here, we investigate the effects of >2600 de novo mutations on gene expression across the transcriptome of 28 mutation accumulation lines derived from two independent wild-type genotypes of the green algae Chlamydomonas reinhardtii...

Large-scale comparative genomics studies offer valuable resources for understanding both functional and evolutionary rate constraints. It is suggested that constraint aligns with the topology of genomic networks, increasing towards the center, with intermediate nodes combining relaxed constraint with higher contributions to the phenotype due to pleiotropy. However, this pattern has yet to be demonstrated in vertebrates. This study shows that constraint intensifies towards the network's center in placental mammals...

Plant-parasitic nematodes are one of the most economically important pests of crops. It is widely accepted that Horizontal Gene Transfer (HGT) - the natural acquisition of foreign genes in parasitic nematodes - contributes to parasitism. However, an apparent paradox has emerged from HGT analyses: On one hand, distantly related organisms with very dissimilar genetic structures (i.e. bacteria), and only transient interactions with nematodes as far as we know, dominate the list of putative donors; while on the other hand, considerably more closely related organism (i...

Advances in genomic studies have revealed that hybridization in nature is pervasive and raised questions about the dynamics of different genetic and evolutionary factors following the initial hybridization event. While recent research has proposed that the genomic outcomes of hybridization might be predictable to some extent, many uncertainties remain. With comprehensive whole-genome sequence data, we investigated the genetic introgression between two divergent lineages of nine-spined sticklebacks (Pungitius pungitius) in the Baltic Sea...

Selective forces in the environment drive bacterial adaptation to novel niches, choosing the fitter variants in the population. However, in dynamic and changing environments, the evolutionary processes controlling bacterial adaptation are difficult to monitor. Here, we follow 9 people with cystic fibrosis chronically infected with Pseudomonas aeruginosa, as a proxy for bacterial adaptation. We identify and describe the bacterial changes and evolution occurring between 15 and 35 years of within host evolution...

Modern humans originated in Africa 300,000 years ago, and before leaving their continent of origin, they underwent a process of intense diversification involving complex demographic dynamics. Upon exiting Africa, different populations emerged on the four other existing continents, shaped by the interplay of various evolutionary processes, such as migrations, founder effects, and natural selection. Within each region, continental populations, in turn, diversified and evolved almost independently for millennia...

Cytonuclear interaction refers to the complex and ongoing process of coevolution between nuclear and organelle genomes, which are responsible for cellular respiration, photosynthesis, lipid metabolism, etc. and play a significant role in adaptation and speciation. There have been a large number of studies to detect signatures of cytonuclear interactions. However, identification of the specific nuclear and organelle genetic polymorphisms that are involved in these interactions within a species remains relatively rare...

Nitrogen is essential for all organisms, but biological nitrogen fixation (BNF) occurs only in a small fraction of prokaryotes. Previous studies divided nitrogenase-gene-carrying prokaryotes into Groups I to IV and provided evidence that BNF first evolved in bacteria. This study constructed a timetree of the evolution of nitrogen-fixation genes and estimated that archaea evolved BNF much later than bacteria and that nitrogen-fixing cyanobacteria evolved later than 1900 million years ago (MYA), considerably younger than the previous estimate of 2200 MYA...

Mountains are the world's most important centers of biodiversity. The Sino-Himalayan Mountains (SHM) are global biodiversity hotspot due to their extremely high species richness and endemicity. Ample research investigated the impact of the Qinghai-Tibet Plateau uplift and Quaternary glaciations in driving species diversification in plants and animals across the SHM. However, little is known about the role of landscape heterogeneity and other environmental features in driving diversification in this region. We utilized whole genomes and phenotypic data in combination with landscape genetic approaches to investigate population structure, demography, and genetic diversity in a forest songbird species native to the SHM, the Red-billed Leiothrix (Leiothrix lutea)...