Biology subjects

Chavarria, T.

Publications and source records attributed to Chavarria, T..

4 recordsLinked to original sources

bioRxiv2026

River network connectivity and postglacial history shape pollen- and seed-mediated gene flow across riparian populations of Myricaria germanica.

River network connectivity and postglacial history jointly shape patterns of pollen-and seed-mediated gene flow in riparian plants, yet their relative contributions across spatial and temporal scales remain incompletely understood. Myricaria germanica Desv., a pioneer riparian shrub formerly widespread along European rivers but now restricted to fragmented headwaters, provides an ideal model to investigate how river systems structure genetic connectivity. We analysed genetic diversity, population structure, and migration across 2,212 individuals from 67 populations spanning 12 Central European river catchments using 20 nuclear and six chloroplast microsatellite loci. By integrating biparentally inherited nuclear markers with maternally inherited chloroplast markers, we disentangled pollen- and seed-mediated gene flow across historical and contemporary timescales. Both marker systems revealed low genetic diversity, high inbreeding, and strong population differentiation. Nuclear microsatellites showed significant isolation by distance and extensive historical connectivity, with coalescent analyses indicating high pollen-mediated gene flow among catchments and identifying the Rhine and Danube as major long-term sources of migrants. In contrast, chloroplast microsatellites exhibited stronger spatial structure, limited admixture, and highly directional historical seed dispersal, consistent with constrained hydrochorous dispersal routes. Contemporary migration analyses further showed that present-day seed-mediated gene flow is largely confined within catchments, despite widespread historical pollen connectivity. Together, these results support a two-phase postglacial history in M. germanica, involving rare, directional seed dispersal during recolonization followed by prolonged pollen-mediated gene flow. Our findings highlight catchments as biologically meaningful management units and underscore the importance of conserving river network connectivity to preserve both the evolutionary legacy and long-term adaptive potential of riparian populations.

genetics↗

bioRxiv2025

Epigenetic reprogramming by 5-aza-dC alters gene methylation and suppresses aggression in founding queens of the California harvester ant Pogonomyrmex californicus.

Epigenetic mechanisms are increasingly recognized as key drivers of phenotypic plasticity in social insects, where the caste and function of an individual is usually not determined by its genotype. These mechanisms may also regulate variation in social behavior or interactions and ultimately social organization. We experimentally manipulated genome-wide DNA methylation in founding queens of Pogonomyrmex californicus using the DNA methylation inhibitor decitabine (5-aza-20-deoxycytidine), to investigate the effect of DNA demethylation on aggressive interactions during colony founding in P. californicus, leading either to colonies with single (i.e., monogyny) or multiple queens (i.e., polygyny). Genome-wide methylation profiling showed widespread gene hypomethylation in treated queens, including those encoding the DNA methyltransferases DNMT1 and DNMT3. Furthermore, treated queens exhibited significantly reduced aggression in queen-queen interactions compared to untreated ones. Interestingly, genes linked to energy metabolism showed increased methylation in aggressive founding queens compared to non-aggressive queens. Our results highlight a potential epigenetic basis for behavioral and social variation, contributing to the understanding of social niche polymorphism in ants.

animal behavior and cognition↗

bioRxiv2025

Castes and developmental stages of the harvester ant P. californicus differ in genome-wide and gene specific DNA methylation

DNA methylation in social insects has been proposed as a key mechanism underlying both reproductive and non-reproductive caste determination by regulating gene expression in response to environmental cues. So far, studies on DNA methylation in social insects have yielded mixed results, with some studies finding no effect on caste determination or worker behaviour while others have reported such effects. In order to link DNA methylation to either process one first needs to show variation in DNA methylation between castes and developmental stages. This study determined cytosin methylation in a CpG context (CmpG) in the harvester ant Pogonomyrmex californicus using ONT (Oxford Nanopore Sequencing) sequencing in larvae, pupae, workers and queens, moreover we compared accuracy of methylation with the gold standard WGBS (Whole Genome Bisulfite Sequencing). Methylation sites were highly correlated between WGBS and ONT (r2=0.8). Overall, the P. californicus genome showed low levels of methylation (3%) which is comparable to what has been found in other Hymenopterans. DNA methylation was significantly increased in gene bodies and in particular exons and showed a significant decrease at the transcription start site and promotor region. Introns, intergenic regions and transposable elements have the lowest levels of DNA methylation. Gene body methylation was positively correlated with gene expression in queens, which is in accordance with other studies and the opposite of what is found in vertebrate studies. Both castes and developmental stages showed significant variation and differences in gene body methylation frequencies. Furthermore, castes and stages which have a high metabolic rate (queens and pupae) show higher DNA methylation, suggesting plasticity and an active role of DNA methylation in gene regulation and in extension caste regulation.

genomics↗

bioRxiv2020

An EMT-primary cilium-GLIS2 signaling axis regulates mammogenesis and claudin-low breast tumorigenesis

The Epithelial-Mesenchymal Transition (EMT) and primary ciliogenesis induce stem cell properties in basal Mammary Stem Cells (MaSCs) to promote mammogenesis, but the underlying mechanisms remain incompletely understood. Here, we show that EMT transcription factors promote ciliogenesis at intermediate EMT transition states by activating ciliogenesis inducers, including FGFR1. The resulting primary cilia promote BBS11-dependent ubiquitination and inactivation of a central signaling node, GLIS2. We show that GLIS2 inactivation promotes MaSC stemness, and GLIS2 is required for normal mammary gland development. Moreover, GLIS2 inactivation is required to induce the proliferative and tumorigenic capacities of the Mammary-Tumor-initiating cells (MaTICs) of claudin-low breast cancers. Claudin-low breast tumors can be segregated from other breast tumor subtypes based on a GLIS2-dependent gene expression signature. Collectively, our findings establish molecular mechanisms by which EMT programs induce ciliogenesis to control MaSC and MaTIC biology, mammary gland development, and claudin-low breast cancer formation.

cell biology↗