Biology subjects

Barbosa, S.

Publications and source records attributed to Barbosa, S..

9 recordsLinked to original sources

bioRxiv2026

ARTIFICIAL SELECTION DIVERSIFIES BIRDSONG THROUGH POLYGENIC CHANGES ACROSS SENSORY AND MOTOR SYSTEMS

Vocal learning, or the ability to acquire and produce contextualized sounds through social interaction, underlies human speech yet has evolved in a few animal lineages, including songbirds. In songbirds, learned song is produced by a dedicated neural circuit and depends on auditory feedback for its acquisition and maintenance. Roughly four centuries of artificial selection on the domestic canary (Serinus canaria) have produced song breeds whose vocalizations diverge as much as those of distinct species, offering a rare intraspecific system in which to identify the genetic and neural changes underlying vocal divergence. Here we show that selection for song reshaped the canary song control system. Compared with breeds selected for plumage or body form, song breeds show increased neural progenitor proliferation and breed-specific changes in neuronal recruitment, sensorimotor brain region volume, and auditory sensitivity. Genome-wide analyses reveal a polygenic architecture underlying song divergence, enriched for transcriptional regulation and synaptic transmission genes. Among these, we find a coding variant in ADGRV1, the gene mutated in human Usher syndrome type 2C, associated with low-frequency singing and elevated auditory thresholds in canary. Disrupting ADGRV1 in zebrafish alters hair cell dynamics, linking adgrv1 mutation to a peripheral sensory mechanism. These findings demonstrate that learned vocal behavior can diversify rapidly through changes spanning sensory, neurogenic, and motor systems, with hearing itself as a substrate for selection.

evolutionary biology↗

bioRxiv2026

The genome sequence of Pavonine herpesvirus 1, a novel Mardivirus infecting peafowl

Avian alphaherpesviruses of the genus Mardivirus include several economically important pathogens, such as the tumour-causing Mareks disease virus (MDV-1) of chickens. However, the diversity of related viruses in wild and non-model avian hosts remains poorly characterised. Here, we describe the genome of Pavonine herpesvirus 1 (PaHv1), a novel Mardivirus infecting peafowl (Pavo spp.). Through de novo assembly of reads generated from whole-genome sequencing of 370 captive peafowl, we generated a single viral genomic scaffold of 134,149 bp in length and an estimated total genome size of [~]146 kbp following reconstruction of terminal repeat regions. PaHv1 exhibits canonical Mardivirus UL-IRL-IRS-US genomic architecture and encodes 169 open reading frames, of which 82 have clear orthologs in other Mardivirus species. Comparative genomic analyses revealed strong syntenic concordance between PaHv1, MDV-1, MDV-2 and Meleagrid alphaherpesvirus 1 (HVT), but with notable absences of the Meq oncogene, viral interleukin-8 (vIL8), and a truncated pp38 gene - genes known to underpin oncogenicity and virulence in MDV-1. Phylogenetic analysis places PaHv1 firmly within the Mardivirus genus as a sister to the poultry-associated MDV-1 and MDV-2 viruses, but distinct from a previously described Phasianid herpesvirus with a partial DNA terminase sequence. PaHv1 was detected predominantly in feather-derived samples, consistent with replication or persistence in the feather follicle epithelium. Taken together, these findings identify PaHv1 as a novel, likely non-oncogenic Mardivirus, expanding our understanding of herpesvirus diversity, evolution and host association in galliform birds. ImportanceHerpesviruses cause several economically important diseases in domesticated birds, including Mareks disease, duck plague and infectious laryngotracheitis. Despite this, our understanding of herpesviruses infecting wild and semi-wild birds remains limited. Here, we present the genome of Pavonine herpesvirus 1 (PaHv1), a virus in the Mardivirus genus which infects peafowl. Based on comparative genomics with other Mardivirus species, we note the absence of several genes important for the high virulence of Mareks Disease Virus, such as the Meq oncogene, viral interleukin-8 and a truncated pp38. This, taken together with absence of clinical disease in preliminary observations, suggests that PaHv1 causes either a subclinical infection or one with mild symptoms. Our work expands the known evolutionary breadth of avian herpesviruses in the Mardivirus genus. In addition, PaHv1 may provide a useful starting point for the development of novel vaccine vectors for pathogenic herpesvirus infections.

genomics↗

bioRxiv2026

Modulation of Avian Iridescence via Malanogenesis

The iridescent colors of birds originate in nanoscale feather structures that interact with light. Although the physical principles governing avian iridescence are well-established, the molecular mechanisms assembling these nanostructures into photonic materials remain unknown. Here, we integrated genomic, cellular, and optical approaches to investigate the molecular basis of iridescent color formation in birds. We leveraged mutations that arose in the domesticated Indian peafowl and natural color variation in wild birds. In peafowl, we identified eight genes underlying gains, losses, and shifts of iridescence, whereas in two wild species, we used single-cell transcriptomics to profile asymmetric feathers in which iridescent and non-iridescent barbules develop on opposite sides of the same feather. We found that all peafowl mutations mapped to melanogenesis genes, showing that variation in this pathway can modify diverse geometric features of feather photonic nanostructures. Mutations altering melanin composition collapsed multilayered photonic systems and yielded non-iridescent tissues, whereas changes in melanosome abundance, elongation, or deposition timing generated multilayer architectures with variable periodicity and color. We further show in peafowl that transitions from non-iridescent to iridescent plumage were associated with single-nucleotide mutations in a melanogenesis gene, suggesting that, in species already capable of forming multilayered nanostructures, iridescence can be gained by relatively small genetic changes. Single-cell transcriptomes from wild species also supported extensive melanocyte-centered regulatory rewiring associated with iridescence, including changes in melanosome maturation, trafficking, and intercellular signaling. Together, these results show that the nanoscale order underlying iridescence is developmentally plastic and highly responsive to the melanogenic environment. Significance StatementBird feathers can produce brilliant, shifting colors, but how these colors form during development has remained poorly understood. By comparing the genomes of color variants of domesticated peafowl and transcriptomes during feather development in wild birds, and combining these with chemical and optical analyses, we show that mutations in genes associated with melanogenesis can profoundly alter the amount, shape, and arrangement of the melanin granules inside feathers that interact with light and produce iridescence. These changes can switch feather appearance between dull and iridescent, or generate entirely new colors by restructuring how those granules are layered at the microscopic scale. Our results reveal a direct and flexible link between pigment production and the physical structures that generate iridescence in birds.

evolutionary biology↗

bioRxiv2026

Microbial metabolite p-cresol associates with constipation in adults with high-functioning autism spectrum disorder and induces constipation-like symptoms in mice

Gastrointestinal (GI) symptoms are prevalent in Autism Spectrum Disorder (ASD), yet their biological correlates remain poorly understood. The gut microbial metabolite p-cresol is reported to be elevated in ASD, but its link to specific GI symptoms in adult high-functioning adults remains unexplored. We examined the relationship between serum levels of p-cresol and its conjugates (p-cresol sulfate, p-cresol glucuronide) with five common GI symptoms (diarrhea, constipation, abnormal stool aspect, bloating, abdominal pain) in 272 adults with high-functioning ASD. Clinical and dietary assessments were performed, and serum metabolites were measured using targeted metabolomics in 177 patients. Females with ASD had higher rates of GI symptoms and elevated p-cresol compared to males. Multivariable regression analysis showed that serum p-cresol, but not its conjugates, was selectively associated with constipation frequency, independent of sex, age, and diet. No associations were observed with the other GI symptoms. In mice, chronic p-cresol exposure induced constipation-like GI dysfunction, supporting a causal link. These findings identify p-cresol as a possible mediator of constipation in ASD. This work supports the development of tailored interventions for GI symptoms in adults with ASD. LAY SUMMARYPeople with autism spectrum disorder (ASD) often experience gastrointestinal (GI) symptoms, but the role of the gut microbiota remains unclear. Elevated levels of p-cresol, a gut microbiota-derived molecule, have been reported in ASD, though its link to specific GI symptoms, particularly in adults, remains unknown. We studied 272 adults with high-functioning ASD and we found that women with ASD reported more frequently GI symptoms and had higher levels of p-cresol than men. Higher p-cresol levels were associated with more frequent constipation, but not with other GI symptoms. In mice, p-cresol treatment induced signs of constipation, suggesting a causal role. Overall, our findings indicate that p-cresol may contribute to constipation in adults with ASD and support the need personalized medical approaches to digestive health in adults with ASD.

microbiology↗

bioRxiv2025

Resolving the evolutionary history of bighorn sheep to inform future management

Although translocations can be effective for augmenting and restoring wild populations, they can disrupt native patterns of genetic structure, diversity, and local adaptation, thereby hampering conservation efforts. Managers must weigh potential costs and benefits of choosing well-differentiated donor individuals that could confer a boost to genetic diversity while avoiding outbreeding depression or ecological mismatch. This decision is more daunting when taxonomy is unclear or debated. For example, bighorn sheep (Ovis canadensis) populations in the United States that have been managed as the "California" lineage (part of the formerly recognized subspecies O. c. californiana) originate from serial translocations sourced from populations in British Columbia, resulting in reduced genetic diversity and elevated risk of inbreeding. After research on skull shape and RFLP analysis of mtDNA failed to find support for that subspecies, some jurisdictions treated the California lineage as part of the Rocky Mountain subspecies (O. c. canadensis) and mixed individuals in subsequent translocations, in part to increase genetic diversity of bottlenecked populations. Yet detailed genetic data addressing validity of those putative lineages were lacking. We reconstructed the genetic history of bighorn sheep by sampling the major putative subspecies or lineages, focusing on native (remnant) genetic variation, and generating high-throughput DNA sequencing data ([~]15,000-25,000 SNPs). Complementary phylogenetic and population genetic analyses supported the distinctiveness of four bighorn lineages at levels corresponding to subspecies. Our results confirm the genetic identity of the no longer putative California bighorn lineage, answering a question that puzzled geneticists and managers for decades. Moving forward, we recommend that managers 1) maintain the natural variation held in native populations by protecting them from intentional translocations or unintentional mixing with nearby populations; 2) prioritize withinlineage translocations for population augmentation or repatriation to previously occupied regions; and 3) cautiously consider any translocations that would lead to mixing of distinct evolutionary lineages.

evolutionary biology↗

bioRxiv2020

Historical and contemporary signatures of selection in response to transmissible cancer in the Tasmanian Devil (Sarcophilus harrisii)

Tasmanian devils (Sarcophilus harrisii) are evolving in response to a unique transmissible cancer, devil facial tumour disease (DFTD), first described in 1996. Persistence of wild populations and the recent emergence of a second independently evolved transmissible cancer suggest that transmissible cancers may be a recurrent feature in devils. Here we compared signatures of selection across temporal scales to determine whether genes or gene pathways under contemporary selection (6-8 generations) have also been subject to historical selection (65-85 million years), and test for recurrent selection in devils. First, we used a targeted sequencing approach, RAD-capture, to identify genomic regions subject to rapid evolution in approximately 2,500 devils in six populations as DFTD spread across the species range. We documented genome-wide contemporary evolution, including 186 candidate genes related to cell cycling and immune response. Then we used a molecular evolution approach to identify historical positive selection in devils compared to other marsupials and found evidence of selection in 1,773 genes. However, we found limited overlap across time scales, with historical selection detected in only 16 contemporary candidate genes, and no overlap in enriched functional gene sets. Our results are consistent with a novel, multi-locus evolutionary response of devils to DFTD. Our results can inform management actions to conserve adaptive potential of devils by identifying high priority targets for genetic monitoring and maintenance of functional diversity in managed populations.

evolutionary biology↗

bioRxiv2020

Gut microbial metabolite p-Cresol promotes autistic-like behaviors in mice through remodeling of the microbiota

BackgroundAutism Spectrum Disorders (ASD) are associated with dysregulation of the microbiota-gut-brain axis resulting in changes in microbiota composition as well as fecal, serum and urine levels of microbial metabolites. Yet, a causal relationship between dysregulation of the microbiota-gut-brain axis and ASD remains to be demonstrated. Here, we hypothesized that the microbial metabolite p-Cresol, which is more abundant in ASD patients compared to neurotypical individuals, could induce ASD-like behavior in mice. ResultsMice exposed to p-Cresol for 4 weeks in drinking water presented social behavior deficits, stereotypies, and perseverative behaviors, but no changes in anxiety, locomotion, or cognition. Abnormal social behavior induced by p-Cresol was associated with decreased activity of central dopamine neurons involved in the social reward circuit. Further, p-Cresol induced changes in microbiota composition and social behavior deficits could be transferred from p-Cresol-treated mice to control mice by fecal microbiota transplantation (FMT). We also showed that mice transplanted with the microbiota of p-Cresol-treated mice exhibited increased fecal p-Cresol levels compared to mice transplanted with the microbiota of control mice and identified possible p-Cresol bacterial producers. Lastly, the microbiota of control mice rescued social interactions, dopamine neurons excitability and fecal p-Cresol levels when transplanted to p-Cresol-treated mice. ConclusionsThe microbial metabolite p-Cresol induces ASD core behavioral symptoms in mice via a gut microbiota-dependent mechanism. Our study paves the way for therapeutic interventions targeting the microbiota to treat patients with ASD.

neuroscience↗

bioRxiv2020

Integration of behavioral and biological variables using penalized regression: an application to the maternal immune activation model of autism

Maternal immune activation (MIA) during pregnancy increases the odds of developing neuropsychiatric disorders such as autism spectrum disorder (ASD) later in life. In pregnant mice, MIA can be induced by injecting the viral mimic polyinosinic:polycytidylic acid (poly(I:C) to pregnant dams resulting in altered fetal neurodevelopmental and behavioral changes in their progeny. Although the murine MIA model has been extensively studied worldwide, the underlying mechanisms have only been partially elucidated. Furthermore, the murine MIA model suffers from lack of reproducibility, at least in part because it is highly influenced by subtle changes in environmental conditions. In human studies, multivariable (MV) statistical analysis is widely used to control for covariates including sex, age, exposure to environmental factors and many others. We reasoned that animal studies in general, and studies on the MIA model in particular, could therefore benefit from MV analyzes to account for complex phenotype interactions and high inter-individual variability. Here, we used a dataset consisting of 26 variables collected on 67 male pups during the course of several independent experiments on the MIA model. We then analyzed this dataset using penalized regression to identify variables associated with in utero exposure to MIA. In addition to confirming the association between some previously described biological variables and MIA, we identified new variables that could play a role in neurodevelopment alterations. Aside from providing new insights into variable interactions in the MIA model, this study highlights the importance of extending the use of MV statistics to animal studies.

neuroscience↗

bioRxiv2019

Disease swamps molecular signatures of genetic-environmental associations to abiotic factors in Tasmanian devil (Sarcophilus harrisii) populations

Landscape genomics studies focus on identifying candidate genes under selection via spatial variation in abiotic environmental variables, but rarely by biotic factors such as disease. The Tasmanian devil (Sarcophilus harrisii) is found only on the environmentally heterogeneous island of Tasmania and is threatened with extinction by a nearly 100% fatal, transmissible cancer, devil facial tumor disease (DFTD). Devils persist in regions of long-term infection despite epidemiological model predictions of species extinction, suggesting possible adaptation to DFTD. Here, we test the extent to which spatial variation and genetic diversity are associated with the abiotic environment and/or by DFTD. We employ genetic-environment association (GEAs) analyses using a RAD-capture panel consisting of 6,886 SNPs from 3,286 individuals sampled pre- and post-disease arrival. Pre-disease, we find significant correlations of allele frequencies with environmental variables, including 349 unique loci linked to 64 genes, suggesting local adaptation to abiotic environment. Following DFTD arrival, however, we detected few of the pre-disease candidate loci, but instead frequencies of candidate loci linked to 14 genes correlated with disease prevalence. Loss of apparent signal of abiotic local adaptation following disease arrival suggests swamping by the strong selection imposed by DFTD. Further support for this result comes from the fact that post-disease candidate loci are in linkage disequilibrium with genes putatively involved in immune response, tumor suppression and apoptosis. This suggests the strength GEA associations of loci with the abiotic environment are swamped resulting from the rapid onset of a biotic selective pressure.

evolutionary biology↗