Biology subjects

Cavallini, M.

Publications and source records attributed to Cavallini, M..

3 recordsLinked to original sources

bioRxiv2025

The end of the American dream: a hard to Swallow reality - How the Barn Swallow (Hirundo rustica) returned from America, a complete mtDNA phylogeny

The barn swallow (Hirundo rustica, H.r.) is one of the most iconic and fascinating migratory birds since ancient times, their philopatry and pair bonding have been the symbol of travellers and lovers throughout history. The barn swallow subspecies complex has been the main focus of many latest papers, focusing mainly on the Eurasian and Levant subspecies (H.r. rustica and H.r. transitiva). The remaining subspecies have either not been studied or few complete mitogenome sequences have been obtained. We present a comprehensive phylogeographic analysis of 580 complete mitochondrial genomes of barn swallows representing all recognized subspecies. We identified 553 unique haplotypes, 166 of which are novel, with high haplotype diversity and notable nucleotide diversity among subspecies. Phylogenetic analysis by maximum parsimony supports a single maternal ancestor and reveals five main haplogroups, confirming and refining prior classifications. A novel, distinct haplogroup (E) was identified for H.r. tytleri, previously classified as a sub-branch of H.r. erythrogaster. The inclusion of 66 hybrid individuals confirmed extensive maternal introgression and revealed multiple cases of mitogenome-subspecies mismatches, notably in savignii, transitiva, and tytleri populations. We further integrated 13 mitogenomes from 12 other Hirundo species, three of which are newly sequenced, to contextualize H. rustica evolution within the genus. Our findings support a southern African origin with subsequent diversification and a northward expansion. This study significantly enhances resolution of barn swallow mitogenomic diversity, revises phylogenetic relationships, identifies new haplogroups, hints at inter-subspecies gene flow and refines coalescent-based divergence times, offering key insights into the evolutionary history and hybridisation patterns of this iconic migratory species.

evolutionary biology↗

bioRxiv2023

Molecular Characterization of the Sea Lamprey Retina Illuminates the Evolutionary Origin of Retinal Cell Types

The lamprey, a primitive jawless vertebrate whose ancestors diverged from all other vertebrates over 500 million years ago, offers a unique window into the primordial formation of the retina. Using single-cell RNA-sequencing, we characterized retinal cell types in lamprey and compared their molecular differentiation and regulatory networks with those in mouse and other jawed vertebrates. Our analysis revealed six cell classes and 74 distinct cell types. We discovered multiple conserved cell types shared between jawless and jawed lineages, including notably rods and cones, ON and OFF bipolar cells, and starburst amacrine cells. The conservation of these cell types indicates their emergence early in vertebrate evolution, highlighting the primal designs of retinal circuits for the rod pathway, ON-OFF discrimination, and direction selectivity. In contrast to this evidence for conservation, the pathways of diversification for amacrine cells and retinal ganglion cells appear to have distinctly diverged between the two lineages. Furthermore, we inferred master regulators in specifying retinal cell classes in both lamprey and macaque and identified common regulatory elements across species, underscoring the ancestral nature of the molecular origins governing retinal cell classes. Altogether, our characterization of the lamprey retina illuminates the evolutionary origin of visual processing in the retina.

evolutionary biology↗

bioRxiv2023

Evolutionary and Developmental Specialization of Foveal Cell Types in the Marmoset

In primates, high-acuity vision is mediated by the fovea, a small specialized central region of the retina. The fovea, unique to the anthropoid lineage among mammals, undergoes notable neuronal morphological changes during postnatal maturation. However, the extent of cellular similarity across anthropoid foveas and the molecular underpinnings of foveal maturation remain unclear. Here, we used high throughput single cell RNA sequencing to profile retinal cells of the common marmoset (Callithrix jacchus), an early divergent in anthropoid evolution from humans, apes, and macaques. We generated atlases of the marmoset fovea and peripheral retina for both neonates and adults. Our comparative analysis revealed that marmosets share almost all its foveal types with both humans and macaques, highlighting a conserved cellular structure among primate foveas. Furthermore, by tracing the developmental trajectory of cell types in the foveal and peripheral retina, we found distinct maturation paths for each. In-depth analysis of gene expression differences demonstrated that cone photoreceptors and Muller glia, among others, show the greatest molecular divergence between these two regions. Utilizing single-cell ATAC-seq and gene-regulatory network inference, we uncovered distinct transcriptional regulations differentiating foveal cones from their peripheral counterparts. Further analysis of predicted ligand-receptor interactions suggested a potential role for Muller glia in supporting the maturation of foveal cones. Together, these results provide valuable insights into foveal development, structure, and evolution. Significance statementThe sharpness of our eyesight hinges on a tiny retinal region known as the fovea. The fovea is pivotal for primate vision and is susceptible to diseases like age-related macular degeneration. We studied the fovea in the marmoset-a primate with ancient evolutionary ties. Our data illustrated the cellular and molecular composition of its fovea across different developmental ages. Our findings highlighted a profound cellular consistency among marmosets, humans, and macaques, emphasizing the value of marmosets in visual research and the study of visual diseases.

neuroscience↗