Biology subjects

Bliss, J.

Publications and source records attributed to Bliss, J..

3 recordsLinked to original sources

bioRxiv2026

Triploid asexual freshwater snails grow faster than sexual diploid conspecifics regardless of dietary phosphorus availability

The number of chromosome sets per nucleus is a fundamental trait, but why this number is nearly always two for multicellular eukaryotes remains unclear. Chromosomes are made of nucleic acids, which possess abundant phosphorus (P). Therefore, producing new chromosomes, as well as generating new cells and organismal growth, demands substantial phosphorus. Yet, because P is often limiting in nature, P availability could influence the prevalence of diploidy versus polyploidy. Here, we compare growth rates of diploid and triploid Potamopyrgus antipodarum, a freshwater snail, relative to P availability. Because diploid P. antipodarum are obligately sexual while obligately asexual individuals are polyploid, costs associated with sensitivity to P limitation in polyploids could also help explain the maintenance of sexual P. antipodarum. We raised juvenile diploid and triploid snails on either P-adequate or P-deficient diets and found that independent of P availability, juvenile triploid asexual snails grew faster and harbored higher P content as adults than sexual diploid conspecifics. Together, these results suggest life-history advantages of polyploidy or asexual reproduction that exacerbate rather than ameliorate the cost of sex. These outcomes suggest that P availability is unlikely to be a main driver of ploidy polymorphism or the maintenance of sex in P. antipodarum.

evolutionary biology↗

bioRxiv2026

Ploidy reorganizes ionomic composition across metabolically active and mineralized tissues.

Genome size, defined as total nuclear DNA content, varies widely within species and can influence cell size, metabolic scaling, and organismal performance. Yet the mechanisms linking genome architecture to phenotype remain unresolved, especially in animals. Because organisms are far-from-equilibrium systems built from interacting chemical elements, genome size variation should reorganize elemental allocation across tissues rather than shift single-element requirements in isolation. We tested this hypothesis in the New Zealand mudsnail (Potamopyrgus antipodarum), which includes co-occurring diploid, triploid, and tetraploid individuals and exhibits strong compartmentalization between metabolically active soft tissue and mineralized shell. We quantified multielemental composition of both tissues and analyzed allocation using additive log-ratios anchored to the measured elemental pool. Tissue type explained most multielemental variance, confirming distinct ionomic regimes for shell and soft tissue. Across tissues, ploidy was associated with significant redistribution of relative elemental allocation despite weak single-element effects. Ploidy-associated imbalances were more pronounced in shell than soft tissue, consistent with long-term integration of elemental fluxes in inert structures and buffering in active tissues. Genome size variation therefore reshapes organismal chemistry through coordinated multielemental redistribution, linking genome architecture to system-level chemical organization.

evolutionary biology↗

bioRxiv2021

Sciara coprophila larvae upregulate DNA repair pathways and downregulate developmental regulators in response to ionizing radiation

Robust DNA damage prevention and repair strategies are crucial to faithful reproduction and inheritance of the genetic material. Although many molecular pathways that respond to DNA damage are well conserved through evolution, the quality and effectiveness of these systems can vary between species. Studies dating back for nearly a century document that the dark-winged fungus gnat Sciara coprophila (Order: Diptera; sub-order: Nematocera) is relatively resistant to irradiation-induced mutations that cause visible phenotypes when compared to the fruit fly Drosophila melanogaster (Order: Diptera; sub-order: Brachycera). However, the molecular responses to irradiation for S. coprophila have yet to be analyzed. To address this gap, we first characterized the effects of ionizing radiation on S. coprophila throughout its life cycle. Our data show that developing S. coprophila embryos are highly sensitive to even low doses of gamma-irradiation, whereas larvae can tolerate up to 80 Gy and still retain their ability to develop to adulthood with a developmental delay of 5 to 8 extra days in the larval stage. To survey the genes involved in the early transcriptional response to irradiation, we compared RNA-seq profiles of larvae with and without radiation treatment. Our analysis showed that 327 genes are differentially expressed in irradiated larvae, with 232 genes upregulated and 95 genes downregulated relative to controls. The upregulated genes were enriched for DNA damage response genes, including those involved in DNA repair, cell cycle arrest, and apoptosis, whereas the down-regulated genes were enriched for developmental regulators, consistent with the developmental delay observed in irradiated larvae. Thus, our study has laid the groundwork to further dissect how Sciara copes with radiation-induced damage.

genomics↗