Non-vertebrate species represent about ~95% of known metazoan (animal) diversity. They remain to this day relatively unexplored genetically, but understanding their genome structure and function is pivotal for expanding our current knowledge of evolution, ecology and biodiversity. Following the continuous improvements and decreasing costs of sequencing technologies, many genome assembly tools have been released, leading to a significant amount of genome projects being completed in recent years. In this review, we examine the current state of genome projects of non-vertebrate animal species. We present an overview of available sequencing technologies, assembly approaches, as well as pre and post-processing steps, genome assembly evaluation methods, and their application to non-vertebrate animal genomes.

Standardized gene nomenclature supports unambiguous communication and identification of the scientific literature associated with genes. To support the increasing number of annotated genomes that are now available for comparative studies, gene nomenclature authorities coordinate the assignment of approved gene names that can be readily propagated across species. Theofanopoulou et al. (Theofanopoulou et al. 2021) propose a new nomenclature for the genes encoding oxytocin and arginine vasopressin and their receptors. Rather than changing to a different nomenclature system, we propose minor updates to the current approved nomenclature of these vertebrate genes to better reflect their evolutionary history. We call on authors, journal editors and reviewers to help support communication and indexing of gene-related publications by working with existing gene nomenclature committees and ensuring that standardized gene nomenclature is routinely used.

The Süttő 21 site is a fissure fill of the freshwater limestone of the Gazda quarry in Süttő. The material was collected between 2017 and 2019, the results are summarised in this article, with a special focus on the small vertebrate fauna of the site and its stratigraphic and paleoecological significance. The fissure fill can be placed around the early/middle Pleistocene boundary (ca. 1.1 and 0.77 Ma). The paleoecological analysis of the herpeto- and mammal fauna of the sequence indicates the proximity of a permanent water body. The lower part of the sequence is dominated by open habitat indicator taxa indicating a cool, dry climate. Towards the upper part of the sequence, the climate remained cool but became wetter, and the vegetation gradually changed to forest-steppe/open forest. The fauna of the Süttő 21 site can be compared with the material of sites, which are of similar age, thus revealing taxonomic and paleoecological differences between different areas of the country. While a warm, dry climate and open vegetation can be reconstructed in the Villány Hills around the early/middle Pleistocene boundary, the northern Hungarian areas had a cooler, wetter climate, and slightly more closed (grove, forest-steppe) vegetation during this period.

The aim of the work was to update the distribution range of Aedes (Stegomyia) albopictus Skuse in the Americas, review the blood feeding patterns and compare the minimum infection rate (MIR) between studies of vertical and horizontal transmission of arboviruses. The current distribution of Ae. albopictus encompasses 21 countries in the Americas. In eleven published papers on the blood feeding pattern of Ae. albopictus, DNA from 16 species of mammals and five species of avian species was found. The most common host is humans, and dogs. We found 24 published papers on the identification of arboviruses in wild populations of Ae. albopictus with the potential to infect humans and animals. Eight arboviruses have been isolated in different studies carried out in Brazil, USA, Mexico, Colombia, and Costa Rica. Fifty-eight percent (14/24) of the publications reported vertical transmission of arbovirus. Positive pools were higher in vertical (8.45%) compared to horizontal transmission (0.97%). This was supported by the MIR, which was 3 times greater in vertical (MIR=3.21) than horizontal transmission (MIR= 1.08). In conclusion, Ae. albopictus is an invasive mosquito with wide phenotypic plasticity to adapt to broad and new areas, high vectorial competence to transmit several arboviruses mainly by transovarial transmission, it can participate in the endemic transmission, and serve as a bridge vector for emerging arboviruses between sylvan, rural, and urban areas.

Gymnophiona, the most poorly known group of extant amphibians, includes elongated limbless tetrapods, with compact ossified skulls and reduced eyes, mainly adapted to fossorial life (only the Typhlonectidae exhibits adaptations for an aquatic or semiaquatic behavior). Caecilians are poorly represented in the fossil record, and despite the low number of fossil specimens described until now (only four taxa, in addition to indeterminate fragmentary material), their fossils play a key role in the knowledge of Lissamphibia origin and evolution, as well as contribute directly to a better understanding of phylogeny, taxonomy and biogeography of extant gymnophionan taxa. These records are scattered throughout geological time (from the Jurassic to the Neogene) and space (they are represented only on North and South America and Africa). Here, we revisit the caecilian fossil record, providing a brief description of all known extinct taxa described so far, along with general remarks about their impact on systematics, time range and geographic distribution of the clade, as well as prospects for future research. Possible calibration constraints based on the caecilian fossil record are provided.

Considering that life on earth evolved about 3.7 billion years ago, vertebrates are young, appearing in the fossil record during the Cambrian explosion about 542 to 515 million years ago. Results from sequence analyses of genomes from bacteria, yeast, plants, invertebrates and vertebrates indicate that receptors for adrenal steroids (aldosterone, cortisol), and sex steroids (estrogen, progesterone, testosterone) also are young, with an estrogen receptor and a 3-ketosteroid receptor first appearing in basal chordates (cephalochordates: amphioxus), which are close ancestors of vertebrates. Through gene duplication and divergence of the 3-ketosteroid receptor, receptors that respond to androgens, glucocorticoids, mineralocorticoids and progestins evolved in vertebrates. Thus, an ancestral progesterone receptor and an ancestral corticoid receptor, the common ancestor of the glucocorticoid and mineralocorticoid receptors, evolved in jawless vertebrates (cyclostomes: lampreys, hagfish). This was followed by evolution of an androgen receptor, distinct glucocorticoid and mineralocorticoid receptors and estrogen receptor-α and -β in cartilaginous fishes (gnathostomes: sharks). Further evolution of mineralocorticoid signaling occurred with the evolution of aldosterone synthase in lungfish, a forerunner of terrestrial vertebrates. Adrenal and sex steroid receptors are not found in echinoderms: and hemichordates, which are ancestors in the lineage of cephalochordates and vertebrates. The evolution of steroid receptors at key nodes in the evolution of vertebrates, in which steroid receptors act as master switches to regulate differentiation, development, reproduction, immune responses, electrolyte homeostasis and stress responses, argues for an important role for steroid receptors in the evolutionary success of vertebrates, considering that the human genome contains about 22,000 genes, which is not much larger than genomes of invertebrates, such as Caenorhabditis elegans (~18,000 genes) and Drosophila (~14,000 genes).

A major driver of declining biodiversity is landcover change leading to loss of habitat. Many studies have estimated large-scale declines in biodiversity, but loss of biodiversity at a local scale due to the immediate effects of development have been poorly studied. California, in particular, is a biodiversity hotspot and has rapidly developed; thus, it is important to understand the effects of development on wildlife. Here, we conducted reconnaissance surveys -- a type of survey often used by consulting biologists in support of environmental review of proposed projects -- to measure changes in relative abundance and richness of vertebrate species in response to urban development. We completed 2 reconnaissance surveys at each of 52 control sites that remained undeveloped at the times of both surveys, and at each of 26 impact sites that had been developed by the time of the second survey. We completed the surveys as part of a before-after, control-impact (BACI) experimental design. Our main interest was on the interaction effect between the before-after phases and control-impact treatment levels, or on the impact of development. We also tested for effects of survey duration, years intervening the surveys in the before and after phases, project area size, latitude, degree of connectedness to adjacent open space, and whether the site was a redevelopment site, infill or not infill. After development, the average number of vertebrate wildlife species we detected declined 48% within the project area, and 66% within the bounds of the project sites. Further, the average number of vertebrate animals we counted declined 90% within the project area, and 89% within the bounds of the project sites. Development impacts measured by the mean number of species detected per survey were greatest for amphibians (-100%), followed by mammals (-86%), grassland birds (-75%), raptors (-53%), special-status species (-49%), all birds as a group (-48%), non-native birds (-44%), and synanthropic birds (-28%). Our results indicated that urban development substantially reduced vertebrate species richness and numerical abundance, even after richness and abundance had likely already been depleted by the cumulative effects of loss, fragmentation, and degradation of habitat in the urbanizing environment. Cumulative effects monitoring is needed, and so are conservation measures to mitigate the effects of urbanization.

The anatomy of mature vertebrate hearts is marked by a looped design, which is roughly characterized by two components: (1), s-shaped (sigmoid) routing of the cardiac flow path(s), and (2,) bilaterally asymmetric (chiral) routing of the cardiac flow path(s). The looped heart design is regarded as a phylogenetically conserved feature among vertebrates and is thought to represent a significant determinant of the cardiac pumping function. It evolves during the embryonic period of development by a morphogenetic process called “cardiac looping”. During the past decades, remarkable progress has been made in the uncovering of the genetic, molecular, and biophysical factors contributing to cardiac looping. Thereby, a special focus was directed on the evolution of a bilaterally asymmetric (chiral) heart configuration, which is said to play a central role in the determination of the alignments and separations of the pulmonary and systemic flow paths in the multi-chambered hearts of tetrapods. In contrast to the recent progress made in uncovering of the biological driver of cardiac looping, our present knowledge about the functional consequences of cardiac looping is at an immature state. This article provides an overview and discussion of the currently available information about the looped design of vertebrate hearts and its functional implications.

This review examines the progressive separation of South America and Africa, which began approximately 145 million years ago during the Early Cretaceous and completed 100 million years ago. The rifting process created the South Atlantic Ocean and profoundly influenced vertebrate evolution on both continents. Initially connected as part of Gondwana, the gradual separation led to vicariant speciation and distinct evolutionary trajectories for previously continuous vertebrate populations. The separation particularly affected terrestrial vertebrates, resulting in parallel evolution of similar ecological niches on both continents, while creating opportunities for endemic lineages to develop. This process explains many modern distribution patterns and evolutionary relationships between South American and African vertebrate taxa, including parallel radiations in groups such as titanosaur dinosaurs during the Cretaceous and later parallel developments in mammals during the Cenozoic. The isolation also contributed to unique characteristics in each continent's modern vertebrate assemblages, such as the distinctive nature of South American primates and African ungulates.

The emergence of vertebrates represents one of the most significant evolutionary transitions in animal history. The earliest definitive vertebrate fossils appear in the Lower Cambrian Period (approximately 525-520 million years ago), with Myllokunmingia fengjiaoa and Haikouichthys ercaicunensis from the Chengjiang biota of China being among the oldest known specimens. These early vertebrates evolved from chordate ancestors, likely similar to modern lancelets (amphioxus). The key transition occurred through the development of neural crest cells, a mineralized skeleton, and a more complex brain. The foundation for vertebrate origins was laid in the Pre-Cambrian with early chordates like Pikaia gracilens, which exhibited basic chordate characteristics. The early Cambrian period witnessed a rapid diversification of vertebrate forms, leading to the establishment of major vertebrate lineages, including both jawless (agnathan) and later jawed (gnathostome) groups.

Small peptides are an important component of the vertebrate immune system. They are important molecules for distinguishing proteins that originate in the host from proteins derived of a pathogenic organism, such as a virus or bacterium. Consequently, these peptides are central for the vertebrate host response to intracellular and extracellular pathogens. Computational models for prediction of these peptides have been based on a narrow sample of data with an emphasis on the position and chemical properties of the amino acids. In past literature, this approach has resulted in higher predictability than models that rely on the geometrical arrangement of atoms. However, protein structure data from experiment and theory are a source for building models at scale, and, therefore, knowledge on the role of small peptides and their immunogenicity in the vertebrate immune system. The following sections introduce procedures that contribute to theoretical prediction of peptides and role in immunogenicity. Lastly, deep learning is discussed as it applies to immunogenetics and the acceleration of knowledge by a capability for modeling the complexity of natural phenomena.

Two-photon imaging of light stimulus-evoked neuronal activity has been used to study all neuron classes in the vertebrate retina, from the photoreceptors to the retinal ganglion cells. Clearly, the ability to study retinal circuits down to the level of single synapses or zoomed out at the level of complete populations of neurons, has been a major asset in our understanding of this beautiful circuit. In this chapter, we discuss the possibilities and pitfalls of using an all-optical approach in this highly light-sensitive part of the brain.

This study investigates the application of fractal geometry to the analysis of vertebrate respiratory systems, focusing on the branching patterns of the bronchial tree across diverse species. Using a combination of mathematical modeling and computational visualization, we explore how fractal dimensions and branching characteristics reflect evolutionary adaptations to various habitats and physiological demands. The research encompasses a range of vertebrates, including humans, horses, dolphins, chickens, iguanas, and bullfrogs, representing diverse taxonomic groups and ecological niches. Our analysis reveals a clear gradient of complexity in respiratory structures, correlating strongly with metabolic rates and environmental adaptations. Mammals, particularly those adapted for high-performance activities like horses, demonstrate the most complex fractal patterns, indicating highly efficient gas exchange systems. In contrast, ectothermic species such as iguanas and bullfrogs exhibit simpler structures, reflecting their lower metabolic demands and alternative respiratory strategies. The study employs fractal dimension calculations, L-system modeling, and lacunarity analysis to quantify and visualize these differences. Our findings suggest that fractal analysis provides valuable insights into the relationship between form and function in vertebrate respiratory systems, offering a novel perspective on comparative physiology and evolutionary biology. This research not only enhances our understanding of respiratory system evolution but also has potential applications in biomimetic design, medical diagnostics, and ecological physiology. It demonstrates the power of interdisciplinary approaches, combining advanced mathematics with biological principles to uncover fundamental patterns in nature.

The evolution of jaws represents one of the most transformative innovations in vertebrate history, fundamentally reshaping both animal anatomy and ecological dynamics. At the core of this innovation lies the neural crest, a unique vertebrate cell population whose molecular and developmental properties enabled the formation of articulated jaws. This review explores how neural crest cells, as multipotent stem cells, contributed to jaw development through their extraordinary capacity to form cartilage, bone, and associated tissues. Beyond the developmental perspective, we examine how the emergence of jawed vertebrates dramatically altered marine ecosystems, leading to new predator-prey relationships and driving an unprecedented diversification of feeding strategies. This innovation triggered an evolutionary arms race that shaped marine biodiversity and established new trophic relationships that persist in modern oceans. Understanding this ancient innovation provides crucial insights into both developmental mechanisms and ecological dynamics that defined vertebrate evolution.

Anterior-tooth (ANT) contacts induce short latency reflex inhibition of human jaw-closing muscles. The jaw is a rigid class 1 lever for pinpoint-targeting muscle force into a single bite-point, the pivoting food particle. See-saw reflex movements around the food particle fulcrum multiply the food-crushing force. Unpredictable jolts of reaction force caused by food-crushing are subjected to the rostral ANT and caudally to the two articulate ends of the jaw triangle. Compression/distraction strains of food-crushing must be monitored and inhibited by withdrawal reflexes. The mesencephalic ganglion (Vmes), neural myelin sheath, and muscle stretch receptors evolved subsequently to the advent of jaws to improve the velocity of proprioceptive and withdrawal reflexes. In mammalians, the spindles of the taut motor units, stretched by the food-fulcrum send excitatory monosynaptic feedback for the efferent neurons of the respective ipsilateral muscle units, via Vmes. In the Vmes, the spindle-input-mediating afferent neurons are coupled with another source of afferent feedback, which is also excitatory, from the back-tooth (BAT) mechanoreceptors. The two sources of excitatory pulses are summated and targeted for the efferent neurons to boost the stretched and taut motor units. Likewise, the afferent feedback from ANT mechanoreceptors is also coupled in the Vmes with concomitant feedback from spindles. The ANT output, however, is inhibitory to negate the excitatory feedback from the stretched jaw-muscle units. The inhibitory feed from ANT temporarily blocks the excitatory potential of masticatory motor efferent neurons to protect the ANT and jaw-joints from inadvertent strains. The inhibitory inputs from ANT alternate with the excitatory inputs from BAT to determine which jaw-closing muscle units are activated or inhibited at any given instant of food-crushing. The Vmes exists in all jawed vertebrates, and its’ evolution was probably motivated by demands for the control of bite force. The monosynaptic unilateral food-crushing excitatory and inhibitory reflexes (UFCR) override the coexisting bilaterally executed feed for jaw muscles from the central nervous system. Hypothesis: The Vmes-mediated UFCR combine neural inputs from tooth contacts with concomitant feedback from muscle stretch receptors for the control of mammalian food-crushing bite force.

Abstract

This review explores the intersection of developmental biology and differential topology in understanding vertebrate ontogenetic constraints. We examine how the topological organization of gene regulatory networks (GRNs) influences developmental trajectories and evolutionary possibilities. By analyzing the mathematical frameworks of differential topology and their application to chromatin architecture, we demonstrate how spatial gene arrangements create constraints that both channel and limit morphological evolution. Special attention is paid to the role of topologically associating domains (TADs) and their conservation across vertebrate lineages, suggesting their fundamental importance in maintaining developmental stability. We propose that the hierarchical nature of GRN topology serves as a primary mechanism for establishing evolutionary constraints while simultaneously facilitating phenotypic innovation within defined parameters. This synthesis provides new insights into how physical genome organization shapes the possibilities and limitations of vertebrate body plan evolution.