Perez, A. P. | bioRxiv Science

bioRxiv2026

Mediterranean dispersal imposed bottlenecks in Neolithic sheep and goats

The Neolithic period in western Eurasia involved major dispersal events, including the translocation of livestock into Europe. These domestic animal translocations likely featured founder effects, fundamentally reshaping their genetic landscape. One well-known example is the Mediterranean dispersal, hypothesised to involve rapid maritime translocation with small founding herds, yet the genetic consequences for the livestock themselves remain poorly understood. To investigate this, we generated 12 palaeogenomes of sheep and goat from La Draga and Cova de lAvellaner, and coanalyzed these with other Neolithic Mediterranean assemblages, including 4 additional novel genomes. We observe a significantly lower genetic diversity and higher runs of homozygosity (ROH) in Iberian sheep and goat populations compared to other ancient European and southwest Asian populations. We quantify the magnitude of the bottleneck in goats at [~]205 Ne, highlighting the severity of the founder event. We further identify species-specific demographic trajectories: goats experienced a severe and prolonged bottleneck, likely driven by regional isolation within the western Mediterranean, intensive exploitation strategies, and small initial founding herds, while sheep were likely more frequently exchanged across the region. Lastly, identity-by-descent (IBD) indicates connectivity along the Mediterranean coast compatible with a cabotage model. This suggests that seaways facilitated rapid initial dispersal but not sustained livestock transfer from southwest Asia, shaping the genetic foundation of Iberian livestock herds. SignificanceThe Neolithic transition in western Eurasia fundamentally restructured human societies, yet the genetic consequences for translocated livestock remain poorly characterized. Analyzing 16 novel palaeogenomes from Mediterranean Neolithic sheep and goats, we demonstrate that maritime dispersal imposed severe founder effects on early Iberian livestock, reducing effective population sizes to as low as [~]205 in goats. Species-specific demographic trajectories reveal that goats experienced prolonged genetic isolation within the western Mediterranean, while sheep maintained broader regional connectivity. Identity-by-descent analyses support a cabotage model of coastal dispersal, indicating that Mediterranean seaways facilitated rapid initial colonization but not sustained genetic exchange with southwest Asian source populations. These findings reveal that the earliest livestock introductions into Europe were demographically constrained events whose genetic signatures persist in the foundations of Iberian pastoral heritage.

genomics↗

bioRxiv2022

Transcriptomic balance and optimal growth are determined by cell size

Cell size and growth are intimately related across the evolutionary scale, and the molecular pathways underlying cell size homeostasis have received much attention over the last decades. However, whether cell size is important to attain maximal growth or fitness is still an open question, and the reasons why a critical size is needed for triggering key transitions of the cell cycle are unknown. We show that growth is a non-monotonic function of volume in yeast cells, with maximal values around the critical size. Comparing small to normal, large and outsized cells, the transcriptome undergoes an extensive inversion that correlates with RNA polymerase II occupancy. Accordingly, highly expressed genes impose strong negative effects on growth when their DNA/mass ratio is altered. A similar transcriptomic inversion is displayed by mouse liver cells of different sizes, suggesting that the uncovered mechanistic implications of cell size on growth and fitness are universal. We propose that cell size is set to attain a properly balanced transcriptome and, hence, maximize growth during cell proliferation.

cell biology↗

bioRxiv2020

Stress granules display bistable dynamics modulated by Cdk

Stress granules are conserved biomolecular condensates that originate in response to many stress conditions. These membraneless organelles contain nontranslating mRNAs and a diverse subproteome, but our knowledge on their regulation and functional relevance is still incipient. Here we describe a mutual-inhibition interplay between stress granules and Cdc28, the budding yeast Cdk. Amongst Cdc28 interactors acting as negative modulators of Start we have identified Whi8, an RNA-binding protein that localizes to SGs and recruits the mRNA of CLN3, the most upstream G1 cyclin, for efficient translation inhibition and Cdk inactivation under stress. However, Whi8 also contributes to recruiting Cdc28 to SGs, where it acts to promote their dissolution. As predicted by a mutual-inhibition framework, the SG constitutes a bistable system that is modulated by Cdk. Since mammalian cells display a homologous mechanism, we propose that the opposing functions of specific mRNA-binding proteins and Cdks subjugate SG dynamics to a conserved hysteretic switch.

cell biology↗