Behavioural phenotyping with small aquatic model organisms: why digital video resolution and bitrate matter

Authors: Hy Do, Florian Kreuder, Xuhui Han, Michael Didham, Savita Kumari, Oskar Wasielewski, Jan Kaslin, Paul A. Ramsland, Dujon, Antoine M., Donald Wlodkowic

Source: Behavioural Pharmacology (Oct 2026)

Abstract

Behavioural analysis with small aquatic model organisms is increasingly applied across diverse areas of biosciences and biomedicine, including ecology, pharmacology, and experimental neurobiology. High-throughput behavioural phenotyping workflows frequently employ organisms such as larval zebrafish (Danio rerio) in multiwell laboratory plates, yet the considerable cost of commercial imaging platforms often limits access for smaller laboratories, early career investigators and researchers in low- and middle-income countries.

Here, we describe a rapid and practical approach for constructing an inexpensive, flexible and fully customisable behavioural data acquisition system suitable for use with a broad range of aquatic model species. We also examine an important but frequently overlooked methodological issue in quantitative behavioural research: how video acquisition parameters, particularly resolution and bitrate, influence the reliability of automated animal tracking.

Using Artemia franciscana nauplii, adult Daphnia carinata, and 7 days postfertilisation larval Danio rerio, we show that video resolution is a major determinant of detection reliability, particularly for very small test organisms. Artemia franciscana could not be reliably tracked in multiarena configurations at resolutions below full high definition, whereas ultra high definition (3840 × 2160 pixels) provided robust detection across all tested species.

We also show that concerns regarding ultra high definition file size can be mitigated by optimising bitrate settings. Moderate compression produced major reductions in file size while preserving detection reliability at practical compression levels.

Together, these findings provide a practical framework for designing affordable and custom animal tracking systems and selecting video acquisition settings that support reliable high-throughput behavioural phenotyping across diverse aquatic species.

When effective anticancer therapies are, in fact, destabilizing the tumor’s Group Phenotypic Composition

Authors: Frédéric Thomas, Dujon, Antoine M., Andriy Marusyk, James DeGregori, Alexandre Fontanella, Margaux Bieuville, Mario Campone, Pascal Pujol, Catherine Alix-Panabières, Laurent Lecam, Benjamin Roche, Matthieu Lacroix, Christophe Hirtz, Laurent Poulain, Jean-Pascal Capp, Ujvari, Beata, Jordan Meliani, Robert Noble, Aurora M. Nedelcu & Robert Gatenby

Source: npj Precision Oncology (Jun 2026)

Abstract

Many cancer therapies achieve durable control without complete tumor eradication, suggesting that disrupting tumor organization may be more critical than killing cells.

We propose that effective treatments converge by destabilizing the tumor’s Group Phenotypic Composition (GPC), the functional and spatial organization of interacting cell populations. When this organization collapses, tumors lose coherence. This perspective provides a unifying framework for designing therapies targeting tumor-level dynamics rather than cell number alone.

Temporal Mapping of Tumor Development in Mice Reveals Late Onset and Benefits of Heterozygosity

Authors: Florence Bernex, François Bonhomme, Nelly Pirot, Audrey Arnal, Pascal Boutinaud, Yoan Buscail, Charlène Berthet, Nathalie Barougier, Dominique Faugere, Cécile Cassan, Déborah Garcia, Benjamin Roche, Dujon, Antoine M., Ujvari, Beata, Frédéric Thomas

Source: Journal of Evolutionary Biology (Jul 2026)

Abstract

Despite decades of cancer research, the stage of life at which cancerous processes lead to tumor formation in various organs remains poorly understood. This uncertainty largely stems from the lack of systematic monitoring of organs across different life stages, resulting in tumors often being detected at various stages of development and making it difficult to determine when they initially emerged and began to grow. Moreover, individuals in real-world settings are exposed to diverse environmental factors that generate substantial inter-individual variability, as lifestyle undeniably contributes to tumorigenesis.

To address this gap, we performed regular histological monitoring of tumoral processes in wild-derived laboratory strain mice maintained under standardized laboratory conditions. We specifically compared three small endocrine organs (ovary, thyroid, and adrenal glands) with four larger organs (lung, liver, mammary gland, and kidney) at different time points across the animals’ lifespan. To introduce realistic genetic variability, we initially crossed wild-derived inbred laboratory strains.

Our findings reveal that the earliest signs of tumor development do not appear before 18 months of age, which is relatively late in the lifespan of these outbred individuals. These results support the view that cancerous processes predominantly emerge in late life and suggest that heterozygosity provides a protective effect, while emphasizing that tumor development remains shaped by interactions with the tissue microenvironment even under controlled conditions.

Selection for Function, Persistence, and Darwinian Evolution

Authors: Thomas, Frédéric; Hamant, Olivier; Lecointre, Guillaume; Poulin, Robert; Selosse, Marc-André; Massol, François; Asselin, Klara; Madsen, Thomas; Ujvari, Beata; Dujon, Antoine M.; Boutry, Justine; Loreau, Michel; Capp, Jean-Pasca

Source: Peer Community Journal (Jul 2026)

Abstract

Darwinian selection (DS), based on heritable variation and differential reproductive success, is central to evolutionary theory. However, many systems in biology, including prebiotic molecular networks, microbial communities, and tumors, persist and exhibit structured dynamics despite lacking clear reproduction or lineage-based inheritance at the relevant level.

Building on, but also critically refining, the concept of selection for function (SF) proposed by Wong et al. (2023), we argue that SF provides a complementary descriptive framework for interpreting such systems. Rather than offering an alternative causal explanation to Darwinian processes, SF emphasizes the differential persistence of functionally coherent configurations over time.

Its main value is heuristic and integrative: it makes persistence-based patterns explicit across systems in which lineage-based descriptions are incomplete, diffuse, or difficult to apply at the focal scale. Although in many biological contexts, the emergence and maintenance of traits are well explained by established Darwinian frameworks (e.g., kin selection, multilevel selection, or mutation–selection dynamics), SF highlights how system-level organization and persistence shape long-term outcomes.

Through examples including seed dormancy, sexual reproduction, symbioses, biofilms, and tumor organization, we illustrate how configurations that may be costly or neutral at the individual level can nevertheless contribute to system-level stability and persistence. SF is particularly informative in systems where reproduction and inheritance are weak, diffuse, or difficult to define, but it remains compatible with Darwinian dynamics when these are present.

By making persistence-based filtering explicit, SF complements existing evolutionary frameworks and provides an additional lens for interpreting complex, multilevel, and non-replicating systems.

Genome Scanning Reveals the Genetic Basis of a Color Pattern Morphotype in an Island Population of the European Adder (Vipera berus)

Authors: Nina Casillas , Bent Petersen , Sarah L F Martin , Kjeld Henrik Ophus , Henrik Bringsøe , Jaelle C Brealey , Vanessa C Bieker , Jaime Morin-Lagos , Dag Dolmen , Thomas Madsen , Rasmus Nielsen , Morten E Allentoft , José Cerca , Michael D Martin

Source: Genome Biology And Evolution (Jun 2026)

Abstract

Color polymorphism is an important trait due to its role in defense strategies, feeding habits, environmental responses such as temperature regulation, and overall fitness. While the genetic basis of color polymorphism is well understood in mammals, it remains relatively understudied in nonavian reptiles. Vipera berus, the European adder, is the most widely distributed and northernmost terrestrial snake in the world.

Similar to other European vipers, V. berus exhibits a range of dorsal color patterns spanning from zig-zag to complete melanism. However, a unique longitudinal dorsal stripe pattern was recently discovered in the isolated Gossa Island (∼45 km2) population of Norway, where ∼5% of snakes exhibit this distinct pattern instead of the common dorsal zig-zag pattern.

In this study, we investigated the genetic basis of the unique phenotype observed on Gossa by combining low-depth whole-genome shotgun sequencing and pairwise FST genome scanning. We discovered a moderately sized, significantly differentiated genomic region containing five associated genes, including the premelanosome gene (PMEL) that encodes a well-known transmembrane glycoprotein that is a key component of melanosome organelles. We implicate a functionally relevant variant in the encoded premelanosome protein.

Our results provide insight into the evolution and genetic basis of pigmentation of squamate reptiles using the unbiased approach of genome scanning, a method that has rarely been used in this context.

Isolation leads to greater clonality and reduced seed production in a temperate seagrass

Authors: Timothy M Smith, Georgina Bramwell, Eric A Treml, Paul H York, Peter I Macreadie, D Jeff Ross, Michael J Keough, Craig D H Sherman

Source: Annals Of Botany (Jan 2026)

Abstract

Background and Aim: Many plants have complex mating systems involving sexual and asexual reproduction. Investment in different reproductive strategies can vary among sub-populations and is linked to local ecological conditions, but the key drivers are not well understood. We aimed to use direct estimates of reproductive investment (flowering and seed production), population genetic surveys and a biophysical model to assess the relationship between connectivity and the relative importance of sexual and asexual reproduction in maintaining seagrass populations. We predicted that populations with high levels of connectivity and investment in flowering and seed production will display higher levels of genotypic diversity, while more isolated populations with lower investment in flowering and seed production will display higher levels of clonality.

Methods: We combined field surveys of flowering and seed production with population genetic surveys and a biophysical dispersal model to assess reproductive effort and patterns of connectivity in the seagrass Heterozostera nigricaulis across 16 sites in a large embayment in south-eastern Australia.

Key Results: Estimates of genotypic diversity varied widely between locations, ranging from highly clonal (R = 0.18) to highly diverse (R = 0.91). Genotypic diversity correlated strongly with local seed production and the inflow of propagules derived from the biophysical dispersal model (pseudo-R2 = 0.73). Sites that receive low numbers of propagules and produce few seeds were more clonal than sites with high propagule inflow and seed density.

Conclusions: These results show that isolated populations have higher levels of clonality and invest less in sexual reproduction. This has important consequences for the managing of declining populations of seagrass where fragmentation and loss of key source populations of propagules may lead to declines in genotypic and genetic diversity and the long-term viability of these important habitat-forming species.

Selection for Function in Complex Distributed Pathological Systems

Authors: Frédéric Thomas, Antoine M. Dujon, Daniel Vaiman, Gerard Eberl, Catherine Alix-Panabières, Pascal Pujol, Beata Ujvari, Jordan Meliani, Aurora M. Nedelcu, Jean-Pascal Capp

Source: Evolutionary Applications (Feb 2026)

Abstract

Pathological processes are often conceptualized as localized phenomena anchored in a primary tumor, a focal lesion, or a single organ. However, growing evidence indicates that many diseases persist and progress as complex distributed systems, maintained by interactions among multiple sites. Building on the emerging framework of selection for function, which can be applied to understand the evolutionary persistence of both replicating and non-replicating entities, we propose that metastases, amyloidoses, fibroses, autoimmune syndromes, granulomatous diseases, and multifocal reproductive disorders can all be understood as complex evolving pathological systems within individuals.

In these contexts, local units such as metastatic nodules, amyloid plaques, or fibrotic foci act as semi-autonomous entities, yet achieve collective persistence through systemic flows, feedback loops, and network-level interactions, where local structuration gives rise to systemic effects. At certain points, lesions that produce mediators can trigger systemic alterations that, in turn, favor the emergence and persistence of additional lesions.

This creates a vicious cycle in which local and systemic dynamics reinforce one another, helping these specific pathological networks to overcome host defense mechanisms and persist (i.e., be ‘selected’ via differential persistence). This perspective unifies seemingly disparate conditions under the principle of system persistence, reframing pathology as an emergent organizational property of a pathological system rather than as isolated local breakdowns of organismal components. It also carries important implications for evolutionary medicine, suggesting a taxonomy of diseases that distinguishes localized from distributed functional pathologies. Clinically, it underscores the need to go beyond focal interventions, advocating instead for therapies that disrupt pathological connectivity, destabilize network coherence, and monitor systemic biomarkers of disease persistence.

Recognizing the role of selection for function in the emergence and persistence of complex pathological systems opens new avenues for both theoretical integration and therapeutic innovation in evolutionary medicine.

Metabolic pathways fuelling devil facial tumour diseases

Authors: Anne-Lise Gérard, Florence Pirard, Caitlin Vanbeek, Antoine M. Dujon, Aaron G. Schultz, Rodrigo K. Hamede, Hannah V. Siddle, Frédéric Thomas, Matthew McKenzie, Mark D. Ziemann, Beata Ujvari

Source: The Febs Journal (Jan 2026)

Abstract

Devil Facial Tumour Diseases (DFTD), threatening Tasmanian devils, consist of two distinct transmissible cancers, DFT1 and DFT2, with differing origins and geographic spread. We investigated the metabolic differences between DFT1 and DFT2, examining cell viability, metabolic outputs, and bulk gene expression.

Using both DFT1 and DFT2 cell lines and biopsies, we found that glycolysis, oxidative phosphorylation, glutamate metabolism, and fatty acid synthesis are all essential for the survival of both tumour types. However, DFT2 exhibited higher rates of glycolysis and lactate generation compared to DFT1.

This coincided with elevated ATP production, cholesterol biosynthesis, and ROS generation, as well as an increased reliance on fatty acid metabolism. Furthermore, DFT2 is less metabolically adaptable than DFT1, being unable to switch to oxidative phosphorylation as DFT1 can when required. These metabolic changes in DFT2, in conjunction with its higher growth rate, suggest a more aggressive cancer phenotype than DFT1.

Our findings highlight distinct metabolic adaptations in DFT2 that may contribute to its competitive advantage.

Time as the Missing Variable: Why Africa (And the Tropics) Need Long-Term Ecological Studies Now More Than Ever

Authors: Luca Luiselli, Thomas Madsen

Source: African Journal Of Ecology (Jan 2026)

Abstract

The ongoing biodiversity crisis is driven primarily by habitat degradation and accelerating climate change, with extreme climatic events increasingly shaping population dynamics across taxa. Detecting and interpreting these effects requires long-term ecological studies, yet such datasets remain rare, including Africa where biodiversity is high and ecological systems are strongly influenced by climatic variability and human land use.

Here we synthesise evidence demonstrating why short- and even medium-term studies often fail to capture the demographic consequences of climate change, especially those driven by rare but severe events such as droughts and floods. Drawing on case studies from temperate and tropical systems—including predator–prey collapses, reptile population crashes and iconic long-term projects such as Gombe and Amboseli—we show how sustained monitoring has transformed ecological understanding and conservation priorities.

We emphasise that Africa’s ecological complexity and prevalence of long-lived species make long-term, population-focused research particularly critical. However, funding structures and institutional constraints frequently undermine continuity. To address this gap, we propose an integrative framework combining targeted long-term ecological research funding, institutional support for data continuity, community-based monitoring and local ecological knowledge, and the integration of diverse data sources.

We argue that long-term monitoring is not a luxury but a scientific and ethical necessity for effective conservation under rapid environmental change.

Empirical evidence for a trade-off between reproduction and tumour dynamics in the freshwater cnidarian Hydra oligactis

Authors: Nikita Stepanskyy; Jordan Meliani; Jácint Tökölyi; Aurora M. Nedelcu; Pascal Pujol; Beata Ujvari; Frédéric Thomas; Antoine M. Dujon

Source: Proceedings Of The Royal Society B-biological Sciences (Aug 2026)

Abstract

Reproduction is a key life-history trait but often comes at the expense of somatic maintenance, including ageing and susceptibility to disease. While reproduction–immunity trade-offs have been experimentally demonstrated in the context of infectious diseases, whether reproduction similarly undermines susceptibility to tumours has remained unclear.

Using the freshwater cnidarian Hydra oligactis, in which tumours arise spontaneously and reproductive effort can be experimentally modulated through food availability, we tested the possibility of a trade-off between reproduction and tumour dynamics. Higher reproductive effort increased the likelihood of tumour development, reduced the probability of remission and increased the likelihood of progression to advanced stages. Resource availability modulated the strength of the trade-off in terms of tumour risk and remission, whereas tumour severity was determined solely by reproductive effort.

Together, these findings provide rare empirical support for a trade-off between reproduction and tumour dynamics, demonstrating that reproductive investment compromises both tumour prevention and control and that its expression can be shaped by environmental conditions. More broadly, they suggest that cancer susceptibility in more complex lineages may instead reflect evolutionary trade-offs that prioritize reproduction over somatic maintenance, helping illustrate one mechanism by which evolutionary trade-offs contribute to the persistence of cancer and to variation in susceptibility across taxa.