Technau joined the journal as Co-Editor-in-Chief in 2014, succeeding Diethard Tautz, and for more than a decade led the journal alongside Jürgen Heinze. Following Heinze’s departure at the end of 2024, Stollewerk joined as Co-Editor-in-Chief in January 2025, and the two worked together until Technau’s departure this summer. That handover sequence matters for continuity, because editorial leadership transitions at society-owned journals are often the moments when scope, standards and community relationships either drift or consolidate. The editorial frames Technau’s tenure as a period of stability for the journal’s scientific quality and its deliberately broad zoological remit, a claim that carries weight given how fragmented the discipline has become over the same period.

The fragmentation is worth unpacking, because it explains why the journal’s next move is significant rather than merely administrative. Zoology today is not a single field but a federation of them: molecular evolution, developmental biology, physiology, morphology, behaviour, ecology, systematics, evolutionary biology and biodiversity science all study animals, yet they often publish in disjointed venues, use different methods, and speak different technical languages. A journal that claims to span that range needs editors who can evaluate work far outside their own specialisation, or an editorial board whose collective expertise covers the entire territory. Technau’s own research program illustrates the kind of integrative perspective the journal has prized. Working with cnidarians, the group that includes corals, jellyfish and sea anemones, he investigates the origin and evolution of animal body plans, using genomic, molecular and developmental approaches to probe fundamental features of animal organisation such as germ layers and nervous systems. Cnidarians occupy a pivotal position on the animal tree, sitting outside the bilaterians, which makes them powerful models for asking which aspects of animal development were present in the common ancestor of all animals and which arose later. That expertise in molecular evolution and evolutionary developmental biology, the editorial notes, has been particularly valuable for a journal dedicated to integrating the many disciplines of modern zoology.

Beyond manuscript-level judgement, the editorial highlights a less visible but arguably more consequential part of the job: building the editorial board itself. The quality of a journal’s peer review depends heavily on whether its Associate Editors collectively cover the field’s diversity, and on whether those editors are drawn from the international community rather than a narrow network. Technau is credited with identifying and recruiting Associate Editors from different areas of zoology and from around the world, cultivating the close exchange between Editors-in-Chief and Associate Editors that shapes a journal’s scientific profile while tying it to the wider research community. Stollewerk also offers a personal note of thanks, describing the collaboration since her arrival in January 2025 as marked by thoughtful judgement and a willingness to discuss both individual manuscripts and broader editorial questions, which she credits with easing her own transition into the role. On behalf of the journal, its Editorial Board and the DZG, she extends warm thanks for his twelve years of commitment.

The incoming Co-Editor-in-Chief brings a complementary profile. Stefan Richter’s research spans morphology, systematics, phylogenetics and evolutionary biology, with a particular focus on understanding organismal diversity and evolutionary relationships. Where Technau’s work reached down to the genomic and developmental basis of body-plan features, Richter’s tradition reaches across the comparative anatomy and phylogenetic reconstruction that have long anchored zoological classification. He also arrives with substantial editorial experience from a number of journals in zoology, systematics and evolutionary biology, which should shorten the learning curve that typically accompanies a handover of this kind. In practical terms, the pairing suggests the journal intends to keep one foot in molecular and developmental zoology and the other in organismal and comparative biology, the two poles between which much of the discipline’s integration problem lies.

Richter’s connection to the journal’s founding society is unusually direct. He served on the Executive Board of the German Zoological Society for many years and was the DZG’s President in 2017 and 2018. The editorial argues that his appointment comes at an especially appropriate time, because Frontiers in Zoology is currently strengthening the integration between the journal and the society that founded it. That relationship is not cosmetic. Society journals live or die by their standing within their disciplinary communities, and the DZG’s subdiscipline groups represent precisely the network of specialists a broad-scope journal needs to draw upon for review, section leadership and agenda-setting.

The concrete expression of that integration is a new editorial structure now being introduced. The expertise of the Editorial Board is being organised into the major subdisciplines of zoology, and authors will be able to submit their work directly to the section most appropriate for their research. Members of the DZG’s corresponding subdiscipline groups have joined the journal as Section Editors and will help develop these sections, further strengthening the connection between the international Editorial Board and the scientific community represented by the society. For authors, the immediate effect is navigational: rather than a single undifferentiated stream of submissions, papers on, say, neurobiology, systematics or behavioural ecology will enter through dedicated channels staffed by editors from those communities. That can shorten the distance between a submission and an editor who genuinely understands the field, improve the matching of reviewers, and signal to readers that the journal’s scope is not nominal but actively curated.

The editorial is careful to frame the reform as an affirmation of an old principle rather than a departure from it. Since its foundation, the journal has operated on the premise that zoology gains its strength from the diversity of its disciplines and from bringing together different approaches to understanding animals, from molecules, development and physiology to morphology, behaviour, ecology, evolution, systematics and biodiversity. The new sections are intended to make that breadth more visible while maintaining the high standards of scientific quality that remain at the heart of the journal. In other words, the structural change is presented as a visibility problem solved: the breadth already existed in the board’s expertise, and the sections simply expose it.

The timing also reflects broader pressures on scientific publishing. Journals across the life sciences are competing for submissions in an environment where preprints, megajournals and specialised outlets all pull at authors’ loyalties, and where society journals must demonstrate added value beyond a brand name. Direct-to-section submission is one of the mechanisms journals use to differentiate themselves, because it promises faster, better-informed editorial triage. For a journal owned by a national zoological society and published open access under a Creative Commons Attribution licence, the calculation is clear: the more visibly the journal maps onto the society’s own disciplinary structure, the more it becomes the natural home for that community’s output, and the more the society’s members have a stake in its success.

What happens next will be watched by authors in organismal biology, a community that has watched several broad-scope zoology venues narrow or reposition over the past decade. The editorial closes with a double gesture that captures the moment: a welcome to Richter and a commitment to work with the Editorial Board, the DZG and the journal’s authors to develop the journal and promote excellent research across the full breadth of zoology, alongside a renewed thanks to Technau for twelve years of dedicated service and best wishes for his future. Leadership changes at journals rarely make headlines, but in a discipline as sprawling as zoology, who sits in the editor’s chair, and how the editorial machinery is organised beneath them, shapes which questions get published, which communities feel at home, and ultimately which strands of animal science stay connected to one another. Frontiers in Zoology has bet that the answer lies in formalising its breadth, one section at a time.

Subject of Research: Editorial leadership transition and new section-based editorial structure at the journal Frontiers in Zoology

Article Title: Continuity and new perspectives at Frontiers in Zoology

Article References: Stollewerk, A. (2026). Continuity and new perspectives at Frontiers in Zoology. Frontiers in Zoology, 23(1), Article 36. https://doi.org/10.1186/s12983-026-00636-z

Image Credits: AI Generated

DOI: 10.1186/s12983-026-00636-z

Keywords: Frontiers in Zoology, zoology, editorial leadership, German Zoological Society, Stefan Richter, Ulrich Technau, evolutionary developmental biology, systematics, open access publishing, editorial board, phylogenetics, scientific journals

The species at the center of the work, Quasipaa spinosa, is a large ranid frog prized in traditional cuisine and increasingly threatened in the wild, which makes understanding its reproductive biology more than an academic exercise. During the breeding season, males clasp females in a tight embrace called amplexus, and the chest spines are thought to help the male anchor himself to the often slippery female in fast-flowing stream water. But while the spines were long noted by field biologists as a striking secondary sexual trait, the structural and molecular machinery that builds them each year had never been systematically characterized. The new study set out to close that gap by combining classical histology with modern high-throughput molecular tools.

The team began by examining the chest skin of males at different points in the annual reproductive cycle: before breeding, during breeding, and after breeding had concluded. Using AB-PAS histological staining, a technique that distinguishes different classes of carbohydrates and secretory products in tissue sections, they revealed that the chest skin of Q. spinosa is not ordinary frog skin. It contains specialized glandular structures and a dermal framework unusually rich in collagen, the fibrous protein that gives skin its tensile strength. This pre-existing scaffold, the authors argue, provides the structural foundation on which the seasonal spines are subsequently built, rather than the spines arising de novo from undifferentiated tissue.

To understand what changes molecularly as the spines grow, the researchers performed quantitative proteomic analysis, comparing the protein content of chest skin across the pre-breeding, breeding and post-breeding stages, and also contrasting chest skin with abdominal skin from the same animals. The comparison identified large numbers of differentially expressed proteins, and the patterns were far from random. Principal component analysis showed that samples from each reproductive stage clustered distinctly, indicating that the chest skin undergoes a coordinated molecular remodeling program as the breeding season approaches, peaks, and passes. Among the protein categories that shifted most dramatically were components of the extracellular matrix, the fibrous and gel-like material that surrounds cells and gives tissues their shape.

That focus on the extracellular matrix, or ECM, is the conceptual heart of the paper. Pathway analysis of the differentially expressed proteins pointed to significant enrichment of ECM-related processes, including focal adhesion signaling and ECM-receptor interactions, the molecular junctions through which cells grip and remodel their surrounding scaffold. In practical terms, the data suggest that spine formation is not simply a matter of cells producing more keratin, but of the entire dermal environment being reorganized: collagen deposited and cross-linked, cell-matrix attachments adjusted, and tissue architecture reshaped to support the emerging keratinized structures. The spines, in this view, are the visible output of a deep remodeling of the skin’s connective-tissue framework.

The proteomic findings were reinforced at the level of gene expression. Using real-time quantitative PCR, the team validated the behavior of genes connected to the TGF-beta/Smad signaling pathway, a canonical regulatory cascade known from developmental biology to control cell growth, differentiation and the production of matrix components. The expression of these genes, along with others involved in matrix remodeling, changed dynamically across the reproductive cycle, rising and falling in step with the growth and subsequent regression of the spines. This concordance between protein-level and transcript-level evidence strengthens the conclusion that TGF-beta/Smad-mediated matrix remodeling is a central mechanism in the seasonal construction of the chest spines, and it offers a concrete molecular handle for future work on how amphibian secondary sexual characters are hormonally and environmentally regulated.

But the most consequential part of the study is its experimental test of function. Correlation between a showy trait and mating success is easy to claim and hard to prove, because attractive males may simply be older, larger or healthier in ways that independently boost their reproductive output. The researchers addressed this directly with reproductive competition experiments in which multiple males competed for access to females, combined with paternity testing based on microsatellite markers, short repetitive DNA sequences that act as genetic fingerprints and allow each offspring to be assigned to its biological father. The results were unambiguous: males whose chest spines were better developed sired more offspring than their rivals, and when the researchers artificially blunted the spines, those males’ reproductive success dropped.

This experimental design matters because it isolates the spines themselves as a causal factor in male reproductive success rather than a mere correlate. The paternity data, generated with SSR markers listed in the study’s supplementary tables, tie the physical condition of the spines directly to the number of offspring each male produced under competitive conditions. Together with the morphological measurements of spine phenotype recorded for each male, the experiments demonstrate that the seasonal spines function as a genuine sexually selected weapon or grip aid, most plausibly by improving a male’s ability to maintain amplexus with a female in turbulent stream environments where rivals and currents alike conspire to dislodge him.

Beyond its evolutionary interest, the work carries practical implications for conservation and aquaculture. Q. spinosa is heavily harvested across its range, and captive breeding programs are increasingly important both for commercial production and for population supplementation. The authors point out that chest spine development could serve as a simple, non-invasive visual indicator of male reproductive performance, allowing hatchery managers to select broodstock males with well-developed spines and thereby improve the genetic output of breeding groups. In wild populations under conservation management, the same trait could be used to gauge the reproductive fitness of males, linking an evolutionarily selected secondary sexual character to the day-to-day business of managing amphibian populations under pressure.

The study also opens broader questions about tissue plasticity in adult vertebrates. The idea that a region of skin can be repeatedly rebuilt each year, dismantled and reconstructed through extracellular matrix remodeling governed by a well-known developmental signaling pathway, resonates with research on antler regeneration, seasonal plumage and nuptial pads in other amphibians. By supplying a full pipeline from histology through proteomics and gene expression to functional paternity testing, the Zhejiang Normal University team has provided one of the most complete accounts to date of how a seasonal secondary sexual trait is built and why it matters. For a species whose survival increasingly depends on managed breeding, knowing that the spines on a male’s chest are both a molecular barometer of his readiness and a reliable predictor of his success as a father turns a curious anatomical feature into a practical conservation tool.

Subject of Research: Seasonal chest spine formation and its role in male reproductive success in the spiny frog Quasipaa spinosa

Article Title: Formation and reproductive significance of chest spines in Quasipaa spinosa

Article References: Peng, X., Piao, Z., Yi, Z., Min, C., Ben, L., & Rongquan, Z. (2026). Formation and reproductive significance of chest spines in Quasipaa spinosa. Frontiers in Zoology. https://doi.org/10.1186/s12983-026-00634-1

Image Credits: AI Generated

DOI: 10.1186/s12983-026-00634-1

Keywords: Quasipaa spinosa, chest spines, extracellular matrix remodeling, TGF-beta/Smad signaling, reproductive success, sexual selection, amphibian conservation, paternity testing, proteomics, secondary sexual traits, broodstock selection, Frontiers in Zoology

The research team focused on two intertwined biological systems: the thyroid gland, the endocrine engine that drives amphibian metamorphosis, and the skin, the organ that must ultimately protect a frog from the drying hazards of terrestrial life. In most familiar frogs, such as the African clawed frog Xenopus laevis, development follows an aquatic indirect pathway: eggs hatch into free-swimming, feeding tadpoles that live in water for weeks or months before a dramatic hormonal surge transforms them into air-breathing, land-capable adults. In contrast, A. villiersi practices what biologists call terrestrial indirect development. Its larvae are endotrophic, meaning they rely entirely on internal yolk reserves rather than feeding, and they metamorphose while still enclosed within the protective jelly of the nest. This lifestyle raises a fundamental question in evolutionary developmental biology: when a lineage shifts its reproduction onto land, do the underlying developmental programs of its organs get rebuilt from scratch, or do they simply run on a slightly adjusted schedule?

To find out, the researchers carried out detailed histological analyses of froglets and larvae across the entire developmental period, examining thin tissue sections under the microscope to track the maturation of the thyroid gland and the step-by-step remodeling of the skin. The thyroid gland is central to the story because in all anurans studied to date, the hormones it produces, chiefly thyroxine and triiodothyronine, orchestrate the sweeping anatomical changes of metamorphosis, from the regression of the tail to the reconstruction of the gut and the maturation of the limbs. Understanding when the thyroid first becomes active, and how its secretory tissue expands over time, therefore provides a hormonal timetable against which every other developmental event can be measured.

The results showed that the sequence of thyroid maturation in the moss frog is conserved, meaning it follows essentially the same ordered progression seen both in classical aquatic indirect developers such as Xenopus and in terrestrial direct developers that skip the tadpole stage entirely. The gland forms, differentiates its hormone-producing follicular cells, and ramps up activity on a schedule that mirrors what has been documented across the frog family tree. This conservation is significant because it suggests that the endocrine control system for metamorphosis is deeply entrenched in anuran biology. Even when an evolutionary transition moves the whole process out of water and into a jelly capsule on land, the hormonal machinery itself does not need to be reinvented.

The skin, however, tells a more nuanced tale. In its earliest stages, the skin of the moss frog tadpole recapitulates features that are typical of free-living aquatic larvae. The young epidermis consists of only two cell layers, and it is studded with unicellular glands, single secretory cells embedded in the surface layer. Most remarkably, the larval skin carries neuromasts, the sensory organs of the lateral line system that fishes and aquatic amphibians use to detect water movements. The presence of these water-sensing organs in a tadpole that never leaves its jelly nest is a vivid example of developmental inertia: the larval program builds the structures it would need for aquatic life, even when that life is spent in a droplet of moisture on a mossy bank.

As metamorphosis proceeds, the skin undergoes the full suite of rearrangements familiar from other frogs. The two-layered larval epidermis is replaced by a three-layered adult epidermis, and a tough outer layer called the stratum corneum forms, providing the keratinized barrier that is essential for surviving exposure to air. The simple unicellular glands are supplanted by multicellular mucus glands, which keep the skin moist, and granular glands, which in many frog species store defensive toxins or antimicrobial compounds. Beneath the surface, the pigment-bearing cells known as melanophores are reorganized into new layers, completing the transition from a larval skin designed for an aquatic existence to an adult skin engineered for terrestrial conditions. In other words, despite the radically different ecological context in which this metamorphosis unfolds, the skin still passes through the same larval architecture and the same adult remodeling as that of a pond-dwelling tadpole.

The timing of these events also revealed telling correlations. The neuromasts appear at hatching, differentiate into functional sensory organs, and then degenerate shortly before the completion of metamorphosis, a schedule that tracks closely with the maturation of the thyroid gland. This coupling makes sense from a physiological standpoint: as thyroid hormone levels rise to drive the adult transformation, larval-specific structures that are no longer needed are systematically eliminated, a process biologists call apoptosis or programmed cell death. The synchronized disappearance of the lateral line organs as the thyroid reaches maturity is a textbook example of how a single hormonal signal can coordinate the simultaneous remodeling of multiple organ systems.

Yet the study did detect subtle differences in timing when the moss frog was compared with aquatic indirect developers using heterochrony plots, graphical tools that map the onset and sequence of developmental events across species. Two shifts stood out. The development of dermal melanophores, the pigment cells embedded in the skin’s connective tissue layer, is pre-displaced, meaning it begins earlier in development than in aquatic tadpoles. Conversely, the formation of multicellular granular glands is post-displaced, occurring later than expected. These are minor adjustments rather than wholesale rewiring, but they hint at how evolution fine-tunes developmental timing to suit new ecological circumstances. An earlier investment in skin pigmentation might be advantageous for an animal developing on land, where protection from ultraviolet radiation and background matching could matter from the moment of hatching, while a delayed deployment of granular glands could reflect the different defensive pressures of a terrestrial jelly nest compared with predator-rich pond water.

Perhaps the most conceptually important finding is what the researchers did not find. Despite the minor timing shifts, there was no evidence of temporal co-dissociation, the phenomenon in which different components of an organ system drift apart in their developmental schedules over evolutionary time. The skin’s various elements, from its epidermal layers to its glands to its pigment cells, all developed in a tightly integrated fashion, leading the authors to describe the skin as an integrated unit of evolution. This modularity has broad implications for how scientists understand morphological evolution. If the skin develops as a coordinated package, then evolutionary changes affecting one component tend to drag the others along, and major life-history transitions, such as the move from aquatic to terrestrial reproduction, can be achieved without fragmenting or fundamentally reorganizing the developmental pathways that build the organ.

Taken together, the study delivers a clear message about the mechanics of evolutionary change in amphibians. The transition to terrestrial life histories in frogs, one of the most ecologically significant shifts in the group’s history, does not require a fundamental overhaul of skin development or thyroid function. Instead, the ancient metamorphic program, governed by a conserved endocrine timetable, can be compressed into a jelly nest on a wet mountainside and still produce a fully functional, land-ready frog. The de Villiers moss frog, by retaining tadpole-typical features such as lateral line organs and unicellular glands even as it completes its development on land, offers a living snapshot of how evolutionary innovation often works not by inventing new biology, but by rescheduling and repurposing the old. As amphibians worldwide face mounting pressures from habitat loss and climate change, understanding the developmental flexibility that allowed some lineages to escape the water may prove more than an academic curiosity; it is a window into the deep reserves of evolvability that have carried frogs through hundreds of millions of years of environmental change.

Subject of Research: Thyroid gland maturation and skin metamorphosis in the terrestrial indirect-developing de Villiers moss frog

Article Title: Temporal patterns of thyroid gland maturation and skin metamorphosis in terrestrial indirect-developing de Villiers moss frogs (Arthroleptella villiersi Hewitt, 1935)

Article References: Naumann, B., Schweiger, S., & Müller, H. (2026). Temporal patterns of thyroid gland maturation and skin metamorphosis in terrestrial indirect-developing de Villiers moss frogs (Arthroleptella villiersi Hewitt, 1935). Frontiers in Zoology. https://doi.org/10.1186/s12983-026-00631-4

Image Credits: AI Generated

DOI: 10.1186/s12983-026-00631-4

Keywords: Arthroleptella villiersi, anuran metamorphosis, thyroid gland, skin development, heterochrony, terrestrialization, evolutionary developmental biology, tadpole, epidermis, lateral line, Frontiers in Zoology, amphibian life history