Biology subjects

Ventura, M.

Publications and source records attributed to Ventura, M..

At least 19 recordsLinked to original sources

bioRxiv2026

Enhanced neural encoding of individual exemplars in the Super-Recogniser brain is specific to faces

Super-Recognisers are known for their exceptional ability to encode and remember faces. Recent work has found robust neural codes for face identity in brain activity. Here we test whether the enhanced individuation of face identity in super-recogniser neural codes extends to exemplars from non-face categories. We recorded 64-channel electroencephalography (EEG) as 22 Super-Recognisers and 20 typical recognisers viewed rapid, randomised sequences of faces, dogs, houses, and cars (10 different images of 10 different exemplars per category). Using a neural decoding approach, we found that Super-Recognisers neural responses contained stronger and more temporally sustained information discriminating individual face identities. Moreover, Super-Recognisers displayed increased inter-individual consistency in the organisation of their face-identity representations, suggesting a more stable and/or canonical representational structure in individuals with superior face recognition abilities. Crucially, there was no evidence to suggest that these encoding advantages generalised to non-face categories: neural discrimination of individual dogs, cars, and houses was comparable across groups, and group-differences in inter-subject consistency were evident only for faces. Together, these findings suggest that enhanced perceptual encoding underlying exceptional face recognition is highly category-specific, supporting the view that expertise in this group reflects specialised mechanisms for processing facial identity rather than broadly enhanced visual discrimination capacities.

neuroscience↗

bioRxiv2026

Robust neural face identity codes in the Super-Recogniser brain

Super-Recognisers show exceptional ability in face recognition, providing a natural model of how perceptual systems optimise for individuating visually similar stimuli in variable viewing conditions. However, the neural representations supporting this extreme perceptual expertise are unknown. Here, we tested whether Super-Recognisers (n = 23) differed from typical recognisers (n = 21) in the dimensional organisation of neural face identity coding. We recorded 64-channel electroencephalography while participants viewed random and rapidly-presented sequences containing 10 naturally varying images of 40 unfamiliar identities. Using time-resolved representational similarity analysis we measured the geometry of identity representations, their consistency across observers, and how clearly they specified face identity. Although neural expression of identity information was robust in both groups, we found three key differences between Super-Recognisers and typical recognisers. First, the geometry of face identity representations differed between groups. Second, Super-Recognisers showed greater inter-individual consistency in representational geometry. Third, Super-Recognisers neural signals discriminated between face identities more strongly than those of typical recognisers. Differences in the coding of broader face categories (sex, age, ethnicity) were notably weaker, suggesting that the observed group differences reflected fine-scale differences in identity coding rather than global reshaping of representational geometry. Strikingly, all three differences emerged within a common mid-latency interval ([~]300-500ms), implicating higher-stages of face processing associated with representations that are sensitive to face familiarity and link between perceptual and semantic domains. Together, these findings indicate that individual differences in face recognition ability reflect higher-level differences in neural identity coding, rather than enhanced early sensory processing. Significance statementSuper-Recognisers have an exceptional ability to recognise unfamiliar faces, yet the neural basis of this advantage has remained unclear. We find brain activity expresses the identity of unfamiliar faces more strongly and consistently in Super-Recognisers than typical recognisers. These advantages were specific to individual identity and could not be explained by enhanced encoding of broader facial categories such as sex, age, or ethnicity. Critically, group differences emerged during a mid-latency stage of processing ([~]300-500 ms) associated with higher-level representations that support stable identity coding across variable images. The findings suggest that exceptional face recognition arises from more robust neural representations of individual identity rather than enhanced early visual processing, providing new insight into the neural basis of perceptual expertise.

neuroscience↗

bioRxiv2026

Rapid centromere turnover and the adaptive radiation of lemurs

Centromeres represent essential chromosomal structures required for faithful chromosome segregation during cell division but are paradoxically hypermutable, leading to centromere drive and reproductive isolation in closely related species. Using long-read sequencing, we generate nearly complete genomes (2.1-2.5 Gbp) from eight lemur species and characterize the sequence, epigenetic and cytogenetic structure of 223 strepsirrhini centromeres providing an alternative primate perspective of centromere evolution. No lemur centromere consists of -satellite DNA that typifies the haplorhine lineage; instead, each species evolved its own distinct higher-order centromeric repeat sequence, varying substantially in both monomer length (ranging from 41-548 bp) and primary sequence composition (GC percentages 28.7-67.9%) including centromere cooption of telomeric repeats in brown lemurs. Most centromeres show characteristic hypomethylation dip regions (110-300 kbp) as candidates for kinetochore attachment. The centromere sequence motif shows no apparent sequence homology among lemur genera, even for species separated by less than 15 million years (Lemur and Eulemur). We estimate a >6-fold increased rate in primary centromeric motif turnover in strepsirrhines when compared to haplorhines and this occurred in conjunction with positive selection of the CENP-B protein in lemur lineages. We propose that lemur radiation and centromere diversification are linked, whereby accelerated motif turnover provides a stasipatric barrier contributing to rapid chromosomal evolution.

genomics↗

bioRxiv2026

A segmental duplication-mediated deletion leads to neocentromere formation in orangutans

Centromeres ensure faithful chromosome segregation, yet how new centromeres arise and replace canonical ones remains poorly understood. Here, we investigate a polymorphic centromere repositioning event on the orangutan chromosome 10 using near-telomere-to-telomere assemblies, epigenetic profiling, and population-scale data. We identify striking heterogeneity in canonical centromeres, ranging from large, higher-order repeat -satellite arrays to short, monomeric -satellite tracts, alongside the emergence of neocentromeres lacking -satellite DNA. We show a segmental duplication-mediated deletion of 3.6 Mbp that removed the higher-order repeat array, promoting centromere repositioning and neocentromere formation. Phylogenetic analyses reveal complex evolutionary dynamics, including introgression and incomplete lineage sorting in orangutan lineages. These findings demonstrate that centromere identity can evolve through structural variation and epigenetic reprogramming, highlighting its remarkable plasticity in primate genomes.

genomics↗

bioRxiv2025

Origin and evolution of acrocentric chromosomes in human and great apes

The short arms of human acrocentric chromosomes are characterized by nucleolar organizer regions essential for ribosome biogenesis, but their highly repetitive nature has hindered genomic analysis. Leveraging the recently completed genomes of all major ape lineages, we identified recurrent features of their acrocentrics, including enriched repeat classes, centromere repositioning by whole-arm inversion, interchromosomal sequence exchange, and birth-and-death evolution of multiple gene families. Together, these processes have enabled the repeated amplification and diversification of the FRG1 gene family over 25 million years of ape evolution, and, in gorilla, the formation and amplification of a novel IGSF3-GGT fusion gene under positive selection. Similar evolutionary events also explain the distribution of segmental duplications and heterochromatin in the modern human genome, predisposing it to karyotypic abnormalities such as Robertsonian translocations. Our findings highlight acrocentric chromosomes as key drivers of evolution in the great apes, with implications for speciation, adaptation, and clinical genomics.

genomics↗

bioRxiv2025

A global view of human centromere variation and evolution

Centromeres are essential for accurate chromosome segregation during cell division, yet their highly repetitive sequence has historically hindered their complete assembly and characterization. Consequently, the full spectrum of centromere diversity across individuals, populations, and evolutionary contexts remains largely unexplored. Here, we address this gap in knowledge by assembling and characterizing 2,110 complete human centromeres from a diverse cohort of individuals representing 5 continental and 28 population groups. By developing a novel suite of bioinformatic tools tailored for centromeric regions, we uncover previously unknown variation within centromeres, including 226 novel centromere haplotypes and 1,870 new -satellite higher-order repeat (HOR) variants. We find that mobile element insertions are present in 30% of centromeres, with chromosome 16 harboring Alu elements within the kinetochore site at an 11-fold higher frequency than expected. While most centromeres have a single kinetochore site, 6% of them have di-kinetochores, and <<1% have tri-kinetochores, which we confirm with long-read CENP-A CUT&RUN, DiMeLo-seq, and multi-generational inheritance. We further show that the position of the kinetochore is not random and is, instead, closely associated with the underlying sequence and structure of the centromere. To understand the nature of evolutionary change, we compared 2,110 complete human centromeres to 5,747 complete centromeres recently assembled from the Human Pangenome Reference Consortium. We show that centromeres have a >50-fold variation in mutation rate, with the most rapidly mutating centromeres on chromosome 1 and the slowest mutating centromeres on chromosome Y. Additionally, a subset of centromeres show evidence of introgression from archaic hominins, shaping their sequence, structure, and evolutionary history. We validate these centromere mutation rates in a four-generation family, spanning 28 family members and 483 accurately assembled centromeres, and show that the kinetochore site is the most rapidly mutating region in the centromere, with twofold more single-nucleotide variants than the rest of the centromeric -satellite HOR array on average. We propose a model that reveals an arms race between centromeric sequence and proteins, with frequent mutations within the site of the kinetochore that lead to changes in genetic and epigenetic landscapes and, ultimately, rapid evolution of these critically important regions.

genomics↗

bioRxiv2025

A complete and near-perfect rhesus macaque reference genome: lessons from subtelomeric repeats and sequencing bias

A truly complete, telomere-to-telomere (T2T), and error-free reference genome remains a foundational resource--and long-standing goal--for unbiased comparative and functional genomics. While recent T2T assemblies of humans and other primates have made substantial progress, most still contain thousands of base-level errors, particularly within highly repetitive regions. Here, we present T2T-MMU8v2.0, a near-perfect T2T assembly of the rhesus macaque (Macaca mulatta), representing the highest base-level accuracy reported in a primate genome to date. By employing an optimized ONT-only assembly strategy, we identify subtelomeric satellite-rich regions as the principal bottleneck to improving assembly quality, owing to technological biases in long-read platforms and limitations in current hybrid assembly frameworks. We discover 268 previously unannotated repeat families and resolve [~]8 Mbp of SATR satellite arrays, with over 99-fold enrichment in historically misassembled subtelomeric regions. These satellites form four distinct genomic architectures, each with unique SATR satellite composition, segmental duplication organization, and epigenetic signatures, distinct from the subtelomeric architectures observed in hominid genomes. Notably, in contrast to the largely gene-poor subtelomeric regions in African hominids, the SATR architectures in macaques harbor 58 actively transcribed genes, supported by open chromatin and expression data, suggesting gene innovation within these repetitive regions. Functionally, T2T-MMU8v2.0 improves read mappability and accuracy across sequencing platforms, and results in a 19% improvement of transcription start site enrichment scores and 5,821 additional chromatin accessibility peaks on average, thereby enhancing variant detection, regulatory annotation, and transcriptomic resolution in population genetics or single-nucleus studies. Together, this work establishes a new benchmark for genomics, offers a roadmap for resolving complex repetitive regions, and reveals previously unrecognized features of subtelomeric genome structure and evolution.

genomics↗

bioRxiv2025

Nuclear Mitochondrial Sequences in Great Ape Telomere-to-Telomere Genomes

Mitochondrial sequences have integrated into the nuclear genome since the origin of eukaryotes. Recent insertions that retain homology to extant mitochondrial DNA (mtDNA), termed NUMTs, confound mtDNA sequence analysis. Here, we used great ape Telomere-to-Telomere (T2T) genomes to study NUMTs in bonobo, chimpanzee, human, gorilla, and Bornean and Sumatran orangutans. A phylogeny based on shared and lineage-specific NUMTs accurately recapitulated the great ape species tree topology. NUMTs were enriched at non-functional non-repetitive regions of the nuclear genome, and depleted within enhancers and coding sequences, suggesting negative selection. We validated the presence of a 76-kilobase-long heterozygous NUMT in chimpanzee, which was larger than any other NUMT observed in great apes, and found that dozens of NUMTs on the Pan Y chromosome expanded together with palindromes. Our study highlights NUMTs as a dynamic evolutionary force contributing to shaping ape genomes, and is valuable for characterizing mtDNA in great apes.

genomics↗

bioRxiv2025

CENdetectHOR: a comprehensive tool for CENtromere profiling and HOR detection

Centromeres are essential for accurate chromosome segregation and are characterized by long arrays of repetitive satellite DNA, showing extensive variation in sequence, length, and organization across species. Despite extensive research, fully characterizing centromeric DNA has been challenging due to its repetitive nature and rapid evolution. Here, we present CENdetectHOR, a computational tool to identify and analyze higher-order repeat (HOR) arrays in centromeric regions across diverse organisms, requiring no a priori information. We validate its efficacy using human and arabidopsis genomes, demonstrating its ability to reveal the complexity and diversity of centromeric architectures. CENdetectHOR also recognizes HOR variants, elucidating interindividual and interspecific variations in centromeric regions. These findings establish CENdetectHOR as a powerful, versatile, and rapid tool for advancing research on centromere structure, evolution, and function.

genetics↗

bioRxiv2024

Correlation between DNA double strand breaks and cell death in peripheral blood lymphocytes from breast cancer patients

Radiotherapy is an effective treatment to fight cancer. However, it not only affects cancer cells but also healthy tissues, causing side effects. Different factors can influence the appearance of radiotoxicity, like total dose administered or patient individual characteristics, such as genetic variability. Several biomarkers have been proposed to predict radiotoxicity, especially those based on apoptosis or DNA damage, for example {gamma}-H2AX, which correlates with DNA double strand breaks. Our purpose is to analyze how apoptosis and {gamma}-H2AX correlate to each other and to link these results with selected SNPs associated with apoptosis. Blood samples from 60 breast cancer patients in remission were recruited. After mononucleated cells isolation, samples were irradiated. Then, we assessed induction and kinetics of disappearance of {gamma}-H2AX at different times after 2-Gy irradiation and apoptosis induced 24 and 48 h after 8-Gy irradiation. A negative correlation was observed between basal and residual {gamma}-H2AX and apoptosis at 48 h post-irradiation. This result supports previous studies with cancer patients showing a negative correlation between these two biomarkers. Considering the high variability of radio-induced apoptosis, we performed a genotyping study. Two SNPs located at TP53 and FAS genes were associated with apoptosis. Overall, our results indicate that individuals with less efficiency in removing damaged cells, probably due to genetic polymorphisms, presented more basal and residual levels of DNA damage.

cell biology↗

bioRxiv2024

Genomic sequencing to detect cross-breeding quality in dogs: an example studying disorders in sexual development

BackgroundDisorders of Sexual Development (DSD) in dogs, similar to humans, arise from irregularities in genetic determinants, gonadal differentiation, or phenotypic sex development. The French Bulldog, a breed that has seen a surge in popularity and demand, has also shown a marked increase in DSD incidence. This study aims to characterize the genetic underpinnings of DSD in a French Bulldog named Brutus, exhibiting ambiguous genitalia and internal sexual anatomy, and to explore the impact of breeding practices on genetic diversity within the breed. MethodsWe utilized a comprehensive approach combining conventional cytogenetics, molecular techniques, and deep sequencing to investigate the genetic profile of Brutus. The sequence data were compared to three other male French Bulldogs genome sequences with typical reproductive anatomy, including Brutuss father, and the canine reference genome (CanFam6). FindingsOur findings revealed a 22% mosaicism (78, XX/77, XX), the absence of the SRY gene, and the presence of 43 unique Single Nucleotide Variants (SNVs) not inherited from the father. Notably, the Run of Homozygosity (ROH) analysis showed Brutus has a significantly higher number of homozygous segments compared to other Bulldogs, with a total length of these fragments 50% greater than the average, strongly suggesting this dog is the product of the mating between siblings. While no direct causative genes for the DSD phenotype were identified four candidate loci warranting further investigation were highlighted. ConclusionsOur study highlighted the need for a better annotated and curated reference dog genome to define genes causative of any specific phenotype, suggests a potential genetic basis for the DSD phenotype in dogs, and underscores the consequences of uncontrolled breeding practices in French Bulldogs. These findings highlight the importance of implementing strategic genetic management to preserve genetic health and diversity in canine populations.

genomics↗

bioRxiv2024

ERGA-BGE genome of Valencia hispanica (Valenciennes, 1826): a critically endangered Iberian toothcarp

The reference genome of Valencia hispanica, a critically endangered actinopterygian species endemic to the Iberian Peninsula, is key to unravelling its genetic architecture and adaptation to freshwater ecosystems. This genomic resource will enable targeted conservation efforts and shed light on the species essential role in ecological dynamics, including its contributions to algal biomass regulation and role in the aquatic food web while also highlighting the challenges it faces from habitat degradation and invasive species. Furthermore, it offers opportunities to gain valuable insights into the evolutionary paths within the Valenciidae family, significantly advancing our comprehension of genetic diversity and adaptability in aquatic ecosystems. The entirety of the genome sequence was assembled into 24 contiguous chromosomal pseudomolecules. This chromosome-level assembly encompasses 1.29Gb, composed of 99 contigs and 28 scaffolds, with contig and scaffold N50 values of 38.3Mb and 56.9Mb, respectively.

evolutionary biology↗

bioRxiv2024

The Aggregated Gut Viral Catalogue (AVrC): A Unified Resource for Exploring the Viral Diversity of the Human Gut

Despite the growing interest in the role of the gut virome in human health and disease, identifying viral sequences from human gut metagenomes remains computationally challenging due to underrepresentation of viral genomes in reference databases. Several recent large-scale efforts have mined human gut metagenomes to establish viral sequence catalogues, using varied computational tools and quality control criteria. However, there has been no consistent comparison of these catalogues quality, diversity, and completeness, nor unification into a comprehensive resource. Here, we systematically surveyed nine previously published human gut viral catalogues, assessing their quality and the overlap of the viral sequences retrieved. While these catalogues collectively screened >40,000 human fecal metagenomes, 82% of the recovered 345,613 viral sequences were unique to one catalogue, highlighting limited redundancy. We further expanded representation by mining 7,867 infant gut metagenomes, retrieving 1,205,739 additional putative viral sequences. From these datasets, we constructed the Aggregated Gut Viral Catalogue (AVrC), a unified modular resource containing 1,018,941 dereplicated viral sequences (449,859 species-level vOTUs). Detailed annotations were generated for sequence quality, taxonomy, predicted lifestyle, and putative host. The AVrC reveals the gut viromes substantial unexplored diversity, providing a pivotal resource for viral discovery. The AVrC is accessible as a relational database and through a web interface allowing customized querying and subset retrieval, enabling streamlined utilization by the research community and future expansions as novel data becomes available. Author summaryThe human gut is home to a vast array of viruses, collectively known as the gut virome, which play a crucial role in human health and disease. Recently, several research groups aiming at providing an overview of the Human gut viral diversity, have created catalogues of viral sequences found in the human gut by analyzing a large number of fecal samples from different individuals. In this study, we compared nine of these existing catalogues and found that there was surprisingly little overlap between them, with 82% of the viral sequences being unique to a single catalogue. To further expand the available data, we analyzed nearly 8,000 additional fecal samples from infants. By combining all this ressources, we created a unified resource called the Aggregated Gut Viral Catalogue (AVrC), which contains more than a million distinct viral sequences, representing nearly 450,000 different viral species. This catalogue, which is easily accessible to the scientific community through a user-friendly web interface, provides a valuable tool for exploring the vast diversity of the human gut virome and its potential implications for human health.

microbiology↗

bioRxiv2024

Fast and reliable ancestral reconstruction on ancient genotype data with non-negative Least square and Principal Component Analysis

The history of human populations has been strongly shaped by admixture events, contributing to the patterns of observed genetic diversity across populations. Given its significance for evolutionary and medical studies, many algorithms focusing on the inference of the genetic composition of admixed populations have been developed. In particular, the recent development of new ancestry estimation methods that consider the fragmentary nature of ancient genotype data, such as the f-statistics family and its derivations, have radically changed our understanding of the past. F-statistics capture similar genetic similarity information as Principal Component Analysis (PCA), which is widely used in population genetics to quantify genetic affinity between populations or individuals. In this study, we introduce ASAP (ASsessing ancestry proportions through Principal component Analysis) method that leverages PCA and Non-Negative Least Square (NNLS) to assess the ancestral compositions of admixed individuals given a large set of populations. We tested ASAP on different simulated models, incorporating high levels of missingness. Our results show its ability to reliably estimate ancestry across numerous scenarios, even those with a significant proportion of missing genotypes, in a fraction of the time required when using other tools. When harnessed on Eurasias genotype data, ASAP helped replicate and extend findings from previous studies proving to be a fast, efficient, and straightforward new ancestry estimation tool.

genomics↗

bioRxiv2024

Comparative genomics of macaques and integrated insights into genetic variation and population history

The crab-eating macaques (Macaca fascicularis) and rhesus macaques (M. mulatta) are widely studied nonhuman primates in biomedical and evolutionary research. Despite their significance, the current understanding of the complex genomic structure in macaques and the differences between species requires substantial improvement. Here, we present a complete genome assembly of a crab-eating macaque and 20 haplotype-resolved macaque assemblies to investigate the complex regions and major genomic differences between species. Segmental duplication in macaques is [~]42% lower, while centromeres are [~]3.7 times longer than those in humans. The characterization of [~]2 Mbp fixed genetic variants and [~]240 Mbp complex loci highlights potential associations with metabolic differences between the two macaque species (e.g., CYP2C76 and EHBP1L1). Additionally, hundreds of alternative splicing differences show post-transcriptional regulation divergence between these two species (e.g., PNPO). We also characterize 91 large-scale genomic differences between macaques and humans at a single-base-pair resolution and highlight their impact on gene regulation in primate evolution (e.g., FOLH1 and PIEZO2). Finally, population genetics recapitulates macaque speciation and selective sweeps, highlighting potential genetic basis of reproduction and tail phenotype differences (e.g., STAB1, SEMA3F, and HOXD13). In summary, the integrated analysis of genetic variation and population genetics in macaques greatly enhances our comprehension of lineage-specific phenotypes, adaptation, and primate evolution, thereby improving their biomedical applications in human diseases.

genomics↗

bioRxiv2023

Metagenomic analysis of milk microbiota in the bovine subclinical mastitis

Subclinical mastitis is one of the most widespread diseases affecting dairy herds with detrimental effects on animal health as well as on milk productivity and quality. Despite the multi-factorial nature of this intramammary infection, the presence of pathogenic bacteria is regarded one of the main drivers of subclinical mastitis, leading to a disruption of the homeostasis of the bovine milk microbial community. However, the bovine milk microbiota alterations associated with subclinical mastitis still represents a largely unexplored research area. In this context, the species-level milk microbiota of a total of 75 milk samples, collected from both healthy and subclinical mastitis-affected cows from two different stables, was deeply profiled through an ITS, rather than a traditional, and less informative, 16S rRNA gene microbial profiling-based sequencing. Surprisingly, the obtained data of the present pilot study, not only revealed that subclinical mastitis is characterized by a reduced number of species in the bovine milk microbiota, but also that this disease does not induce standard alterations of the milk microbial community across stables. In addition, a flow cytometry-based total bacterial cell enumeration highlighted that subclinical mastitis is accompanied by a significant increment in the number of milk microbial cells. Furthermore, the combination of the metagenomic approach and total bacterial cell enumeration allowed to identify different potential microbial marker strictly correlated with subclinical mastitis across stables.

microbiology↗

bioRxiv2022

Multiple invasions, Wolbachia and human-aided transport drive the genetic variability of Aedes albopictus in the Iberian Peninsula

The Asian tiger mosquito, Aedes albopictus, is a highly invasive species that has been spreading rapidly throughout tropical and temperate regions worldwide since the late 1970s. On the Iberian Peninsula, it was first recorded in 2004 near Barcelona. Since then, the species has spread along the Mediterranean coast and is now colonising the Peninsulas inner territories. As with other species of the genus Aedes, the spread of the tiger mosquito has been linked to global shipping routes and road networks. In particular, the transport of adult mosquitoes by car has been shown to augment its natural spreading capacity by orders of magnitude. Much remains unknown, however, about the impact of human-mediated dispersal on the genetic variability of this species. This study aimed to ascertain the factors that have contributed to the spread and the current genetic variation of Ae. albopictus across the Iberian Peninsula, through complex dispersal mechanisms and endosymbiosis with bacteria like Wolbachia. We do so through population genetic analysis of mitochondrial (COI) and nuclear (ITS2) DNA sequences. Overall, both COI and ITS2 markers showed a lack of genetic structure among sampled regions and the presence of worldwide dominant haplotypes, suggesting a pattern of multiple introductions from abroad. We found extremely low levels of variation in COI compared to ITS2, and this lack of mitochondrial polymorphism is likely explained by high Wolbachia prevalence (79%). Multilevel models revealed that greater mosquito fluxes (estimated from commuting patterns and tiger mosquito population distribution) and spatial proximity between sampling sites were associated with lower ITS2 genetic distance, suggesting that rapid short- and medium-distance dispersal is facilitated by humans through vehicular traffic. This study highlights the significant role of human transportation in shaping the genetic attributes of Ae. albopictus and promoting regional gene flow, and underscores the need for a territorially integrated surveillance across scales of this disease-carrying mosquito. Author SummaryThe tiger mosquito, Aedes albopictus, is one of the most invasive species in the world. Native to the tropical forests of Southeast Asia, over the past 30 years it has rapidly spread throughout tropical and temperate regions of the world. Its dramatic expansion has resulted in public health concerns as a consequence of its vector competence for at least 16 viruses. Previous studies showed that Ae. albopictus spread has been facilitated by human-mediated transportation, but much remains unknown about how this has affected its genetic attributes. Here we examined the factors that contributed to shaping the current genetic constitution of Ae. albopictus in the Iberian Peninsula, where the species was first found in 2004, by combining population genetics and Bayesian modelling. We found that both mitochondrial and nuclear DNA markers showed a lack of genetic structure and the presence of worldwide dominant haplotypes, suggesting regular introductions from abroad. Mitochondrial DNA showed little genetic diversity compared to nuclear DNA, likely explained by infection with maternally transmitted bacteria of the genus Wolbachia. Our models indicated that human transportation plays a role in shaping Ae. albopictus nuclear genetic structure by means of passive dispersal of adult tiger mosquitoes through the road network.

genetics↗

bioRxiv2022

Contrasting patterns of genetic admixture explain the phylogeographic history of Iberian high mountain populations of midwife toads

Multiple Quaternary glacial refugia in the Iberian Peninsula, commonly known as "refugia within refugia", allowed diverging populations to come into contact and admix, potentially boosting substantial mito-nuclear discordances. In this study, we employ a comprehensive set of mitochondrial and nuclear markers to shed light onto the drivers of geographical differentiation in Iberian high mountain populations of the midwife toads Alytes obstetricans and A. almogavarii from the Pyrenees, Picos de Europa and Guadarrama Mountains. In the three analysed mountain regions, we detected evidence of extensive mito-nuclear discordances and/or admixture between taxa. Clustering analyses identified three major divergent lineages in the Pyrenees (corresponding to the eastern, central and central-western Pyrenees), which possibly recurrently expanded and admixed during the succession of glacial- interglacial periods that characterised the Late Pleistocene, and that currently follow a ring-shaped diversification pattern. On the other hand, populations from the Picos de Europa mountains (NW Iberian Peninsula) showed a mitochondrial affinity to central-western Pyrenean populations and a nuclear affinity to populations from the central Iberian Peninsula, suggesting a likely admixed origin for Picos de Europa populations. Finally, populations from the Guadarrama Mountain Range (central Iberian Peninsula) were depleted of genetic diversity, possibly as a consequence of a recent epidemic of chytridiomycosis. This work highlights the complex evolutionary history that shaped the current genetic composition of high mountain populations, and underscores the importance of using a multilocus approach to better infer the dynamics of population divergence.

genetics↗