Vertebrate Classes Research Articles

Shifting boundaries: taxonomy and site‐based conservation

Shifting boundaries: taxonomy and site‐based conservation

Can Cephalopods Vomit? Hypothesis Based on a Review of Circumstantial Evidence and Preliminary Experimental Observations.

In representative species of all vertebrate classes, the oral ejection of upper digestive tract contents by vomiting or regurgitation is used to void food contaminated with toxins or containing indigestible material not voidable in the feces. Vomiting or regurgitation has been reported in a number of invertebrate marine species (Exaiptasia diaphana, Cancer productus, and Pleurobranchaea californica), prompting consideration of whether cephalopods have this capability. This “hypothesis and theory” paper reviews four lines of supporting evidence: (1) the mollusk P. californica sharing some digestive tract morphological and innervation similarities with Octopus vulgaris is able to vomit or regurgitate with the mechanisms well characterized, providing an example of motor program switching; (2) a rationale for vomiting or regurgitation in cephalopods based upon the potential requirement to void indigestible material, which may cause damage and ejection of toxin contaminated food; (3) anecdotal reports (including from the literature) of vomiting- or regurgitation-like behavior in several species of cephalopod (Sepia officinalis, Sepioteuthis sepioidea, O. vulgaris, and Enteroctopus dofleini); and (4) anatomical and physiological studies indicating that ejection of gastric/crop contents via the buccal cavity is a theoretical possibility by retroperistalsis in the upper digestive tract (esophagus, crop, and stomach). We have not identified any publications refuting our hypothesis, so a balanced review is not possible. Overall, the evidence presented is circumstantial, so experiments adapting current methodology (e.g., research community survey, in vitro studies of motility, and analysis of indigestible gut contents and feces) are described to obtain additional evidence to either support or refute our hypothesis. We recognize the possibility that further research may not support the hypothesis; therefore, we consider how cephalopods may protect themselves against ingestion of toxic food by external chemodetection prior to ingestion and digestive gland detoxification post-ingestion. Reviewing the evidence for the hypothesis has identified a number of gaps in knowledge of the anatomy (e.g., the presence of sphincters) and physiology (e.g., the fate of indigestible food residues, pH of digestive secretions, sensory innervation, and digestive gland detoxification mechanisms) of the digestive tract as well as a paucity of recent studies on the role of epithelial chemoreceptors in prey identification and food intake.

Adrenal gland response to endocrine disrupting chemicals in fishes, amphibians and reptiles: A comparative overview

The adrenal gland is an essential component of the body stress response; it is formed by two portions: a steroidogenic and a chromaffin tissue. Despite the anatomy of adrenal gland is different among classes of vertebrates, the hormones produced are almost the same. During stress, these hormones contribute to body homeostasis and maintenance of ion balance. The adrenal gland is very sensitive to toxic compounds, many of which behave like endocrine-disruptor chemicals (EDCs). They contribute to alter the endocrine system in wildlife and humans and are considered as possible responsible of the decline of several vertebrate ectotherms. Considering that EDCs regularly can be found in all environmental matrices, the aim of this review is to collect information about the impact of these chemical compounds on the adrenal gland of fishes, amphibians and reptiles. In particular, this review shows the different behavior of these “sentinel species” when they are exposed to stress condition. The data supplied in this review can help to further elucidate the role of EDCs and their harmful impact on the survival of these vertebrates.

Identifying error and accurately interpreting environmental DNA metabarcoding results: A case study to detect vertebrates at arid zone waterholes.

Environmental DNA (eDNA) metabarcoding surveys enable rapid, noninvasive identification of taxa from trace samples with wide-ranging applications from characterizing local biodiversity to identifying food-web interactions. However, the technique is prone to error from two major sources: (a) contamination through foreign DNA entering the workflow, and (b) misidentification of DNA within the workflow. Both types of error have the potential to obscure true taxon presence or to increase taxonomic richness by incorrectly identifying taxa as present at sample sites, but multiple error sources can remain unaccounted for in metabarcoding studies. Here, we use data from an eDNA metabarcoding study designed to detect vertebrate species at waterholes in Australia's arid zone to illustrate where and how in the workflow errors can arise, and how to mitigate those errors. We detected the DNA of 36 taxa spanning 34 families, 19 orders and five vertebrate classes in water samples from waterholes, demonstrating the potential for eDNA metabarcoding surveys to provide rapid, noninvasive detection in remote locations, and to widely sample taxonomic diversity from aquatic through to terrestrial taxa. However, we initially identified 152 taxa in the samples, meaning there were many false positive detections. We identified the sources of these errors, allowing us to design a stepwise process to detect and remove error, and provide a template to minimize similar errors that are likely to arise in other metabarcoding studies. Our findings suggest eDNA metabarcoding surveys need to be carefully conducted and screened for errors to ensure their accuracy.

Fibroblastic osteosarcoma in a white-eared opossum (Didelphis albiventris)

ABSTRACT: Osteosarcoma is characterized by the production of osteoid or woven bone, using neoplastic osteoblasts. It is the most common primary bone neoplasm in canines and humans. This neoplasm was previously reported in all vertebrate classes, including a wide variety of mammals. However, there is no case report describing this neoplasm in Didelphis albiventris. Therefore, the objective of this manuscript is to describe the clinical-pathological aspects of fibroblastic osteosarcoma in D. albiventris. A wild adult male white-eared opossum (D. albiventris) arrived at the zoological park of the “Universidade de Caxias do Sul” with a swollen left thoracic limb. After a general clinical examination, the animal was transferred to the Veterinary Clinic of “Universidade de Caxias do Sul” for radiographic examination of the left thoracic limb and thorax. Additionally, some material was collected through fine needle aspiration (FNA) for cytologic evaluation. The radiographic findings and cytologic evaluation indicated osteosarcoma. The animal was euthanized due to severe clinical conditions and guarded prognosis. During necropsy, macroscopic analysis of the viscera was performed, fragments of various organs were collected and fixed in 10% neutral buffered formalin. All fragments were processed following routine histological techniques. The histopathological evaluation confirmed osteosarcoma, which was classified as a fibroblastic subtype. Case reports are crucial for the knowledge of incidence, prevalence, and behavior of the current mentioned disease, as well as other diseases, in species with such limited information. In order to obtain a decisive diagnosis, a few different examination methods were associated. Although the observations presented are based on a single case, this neoplasm had a similar clinical presentation to that described in other species.

Accelerated loss of hypoxia response in zebrafish with familial Alzheimer’s disease-like mutation of presenilin 1

Ageing is the major risk factor for Alzheimer's disease (AD), a condition involving brain hypoxia. The majority of early-onset familial AD (EOfAD) cases involve dominant mutations in the gene PSEN1. PSEN1 null mutations do not cause EOfAD. We exploited putative hypomorphic and EOfAD-like mutations in the zebrafish psen1 gene to explore the effects of age and genotype on brain responses to acute hypoxia. Both mutations accelerate age-dependent changes in hypoxia-sensitive gene expression supporting that ageing is necessary, but insufficient, for AD occurrence. Curiously, the responses to acute hypoxia become inverted in extremely aged fish. This is associated with an apparent inability to upregulate glycolysis. Wild-type PSEN1 allele expression is reduced in post-mortem brains of human EOfAD mutation carriers (and extremely aged fish), possibly contributing to EOfAD pathogenesis. We also observed that age-dependent loss of HIF1 stabilization under hypoxia is a phenomenon conserved across vertebrate classes.

Amphibian Disease Ecology: Are We Just Scratching the Surface?

Pathogen-induced population declines and extinction events have been recognized as main threats to amphibian species around the globe. However, the ecological drivers underlying epidemiological patterns are still poorly understood. In an attempt to assess the current knowledge on the ecological drivers of amphibian diseases, we identified 832 peer-reviewed publications on the ecology of amphibian pathogens and diseases published between 2009 and 2019. The vast majority of publications investigated either chytrid or ranavirus infections (79% of the articles), whereas other pathogens such as bacteria and helminths received considerably less attention. Just over half of the studies we reviewed included field research and 40% were experimental in nature, yet only 8% combined field and experimental approaches. More than half of the literature (56%) investigated postmetamorphic stages, whereas premetamorphic stages were considered in 23% of the reviewed studies, and only 13% included both life stages. Susceptibility and mortality have been assessed in almost every study (91%) whereas 37% of them tested for cellular, physiological, or immunological responses. However, other host characteristics such as growth/development, behavior, and specific mucosome/microbiome were considered in only one of four studies. Most research included at least one biotic factor (e.g., host and pathogen identity, species diversity, genetic adaptations), but only one-third considered environmental factors (e.g., temperature, landscape features, inorganic chemicals). Furthermore, there is no general consensus about the factors driving epidemiological patterns of pathogens in amphibian communities, and it is clear that the complexity and specificity of interactions between ecological factors and host–pathogen dynamics make conservation implications difficult and management decisions challenging. To this end, our review identifies some research gaps and proposes future directions to better understand one of the major threats to this class of vertebrates.

The function of miR-122 in the lipid metabolism and immunity of grass carp (Ctenopharyngodon idellus)

Abnormal lipid metabolism in the liver due to excessive fat accumulation is a widespread problem in fish. MicroRNA-122 (miR-122), a liver-specific miRNA in vertebrates, is involved in lipid metabolism. In this study, miR-122 was cloned, and its function was investigated in grass carp. MiR-122 is 99 bp in length, showing 70 % similarity to that of other species and is specifically expressed in liver tissue. After transfection with miR-122 agomir for 24 h in liver cells, we found that the overexpression of miR-122 significantly increased the TG content in cells (P < 0.05), while the expression level of transcription factors related to lipid synthesis was significantly increased (P < 0.05). After injection of miR-122 agomir in vivo, the TG content in the liver increased significantly (P < 0.05), and the mRNA expression of lipid synthesis-related genes (PPARγ, SREBP-1c, ACC, FAS and H-FABP) increased significantly (P < 0.05). The relative expression of the proinflammatory factors TNF-α, IL-6, and IL-1β also increased significantly (P < 0.05), while the relative abundance of the anti-inflammatory factors IL-10 and TGF-β1 decreased significantly (P < 0.05). In addition, we found that miR-122 regulated lipid catabolism-related genes through AMPK, and AMPK may regulate lipid synthesis-related genes through miR-122 directly or indirectly. In summary, the comparison of miRNA-122 from genomic sequences reveals strong conservation of miRNA-122 across vertebrate classes; however, its function shows species-specific actions in grass carp and mammalian models. This study provides basic data for further investigation of a miRNA related to fatty liver and other metabolic diseases.

Comparing the effect of triadimefon and its metabolite on male and female Xenopus laevis: Obstructed growth and gonad morphology

Amphibians are the most endangered class of vertebrates. In this study, Xenopus laevis frogs were exposed to 0, 1 and 10 mg/L of triadimefon or triadimenol. After 14 or 28 days of exposure, high levels of triadimefon or triadimenol obstructed the growth of frogs. However, low levels of triadimefon induced the growth of females after the longer period of exposure. We also found that the antioxidant enzyme activity and LDH levels in males were higher than those in females after 28-days exposure. In histopathology tests, triadimenol exerted more effect on the ovary while triadimefon exerted more effect on the testes. Additionally, the levels of Estradiol in all 14-day treatments, except 1 mg/L triadimenol, were significantly decreased, however, there was no difference in testosterone levels. Furthermore, triadimefon and triadimenol disrupted the expression of genes controlling hormone homeostasis and reproduction, and this effect depended on the exposure time and the gender of the organism. Our experiments explored the effect of triadimefon and its metabolite on the gonads of frogs and highlighted the role that pesticides are likely to play in the global decline of amphibians.

Secretion and Function of Pituitary Prolactin in Evolutionary Perspective.

The hypothalamo-pituitary system developed in early vertebrates. Prolactin is an ancient vertebrate hormone released from the pituitary that exerts particularly diverse functions. The purpose of the review is to take a comparative approach in the description of prolactin, its secretion from pituitary lactotrophs, and hormonal functions. Since the reproductive and osmoregulatory roles of prolactin are best established in a variety of species, these functions are the primary subjects of discussion. Different types of prolactin and prolactin receptors developed during vertebrate evolution, which will be described in this review. The signal transduction of prolactin receptors is well conserved among vertebrates enabling us to describe the whole subphylum. Then, the review focuses on the regulation of prolactin release in mammals as we have the most knowledge on this class of vertebrates. Prolactin secretion in response to different reproductive stimuli, such as estrogen-induced release, mating, pregnancy and suckling is detailed. Reproduction in birds is different from that in mammals in several aspects. Prolactin is released during incubation in avian species whose regulation and functional significance are discussed. Little information is available on prolactin in reptiles and amphibians; therefore, they are mentioned only in specific cases to explain certain evolutionary aspects. In turn, the osmoregulatory function of prolactin is well established in fish. The different types of pituitary prolactin in fish play particularly important roles in the adaptation of eutherian species to fresh water environments. To achieve this function, prolactin is released from lactotrophs in hyposmolarity, as they are directly osmosensitive in fish. In turn, the released prolactin acts on branchial epithelia, especially ionocytes of the gill to retain salt and excrete water. This review will highlight the points where comparative data give new ideas or suggest new approaches for investigation in other taxa.

Midkine-a functions as a universal regulator of proliferation during epimorphic regeneration in adult zebrafish.

Zebrafish have the ability to regenerate damaged cells and tissues by activating quiescent stem and progenitor cells or reprogramming differentiated cells into regeneration-competent precursors. Proliferation among the cells that will functionally restore injured tissues is a fundamental biological process underlying regeneration. Midkine-a is a cytokine growth factor, whose expression is strongly induced by injury in a variety of tissues across a range of vertebrate classes. Using a zebrafish Midkine-a loss of function mutant, we evaluated regeneration of caudal fin, extraocular muscle and retinal neurons to investigate the function of Midkine-a during epimorphic regeneration. In wildtype zebrafish, injury among these tissues induces robust proliferation and rapid regeneration. In Midkine-a mutants, the initial proliferation in each of these tissues is significantly diminished or absent. Regeneration of the caudal fin and extraocular muscle is delayed; regeneration of the retina is nearly completely absent. These data demonstrate that Midkine-a is universally required in the signaling pathways that convert tissue injury into the initial burst of cell proliferation. Further, these data highlight differences in the molecular mechanisms that regulate epimorphic regeneration in zebrafish.

Blood and Merogonic Stages of Haemogregarina Species Naturally Infecting The Nile Monitor Varanus niloticus, Egypt

Haemogregarines are haemoparasites (Apicomplexa: Adeleiorina) of all class of vertebrates nearly, worldwide. The present study was aimed to establish and describe the developmental stages of a Haemogregarina species infecting Nile monitor (Varanus niloticus). The captured Nile monitors were three animals with 80-100 cm in length, they captured from Qena province, Southern Egypt, and thin blood films were prepared and microscopically examined. Also, small pieces of the liver and the lungs of the infected animals were separated and prepared for sectioning, which stained and examined. The recovered parasites have rod-like bodies, infecting the erythrocytes only, with a single stage, in a parasitophorous vacuole and have no karyolitic effect. The parasitaemia level was found up to 5010,000 counted erythrocytes. Only gamonts have been recognized in blood smears, and they were found in two forms; the first form is short, thick (called short gamont) and measured 11.02 × 2.65 µm. The second form was found long and thin (called long gamont), with a subterminal nucleus, measured 14.18 × 2.45 µm. Both forms cause either slightly or strong displacement of the host cell nucleus. The infected erythrocytes had either slightly or markedly hypertrophied in presence of short and long gamonts. The infected erythrocyte measured 18.05 × 8.87 µm, but the uninfected erythrocyte was 16.52 × 8.77 µm in length and width, respectively. Schizogony phase was observed in the lungs only of the infected Nile monitor, where the meronts were formed within parasitophorous vacuoles. The parasite nucleus divided many times, and the produced nuclei are peripherally arranged in the meront, forming merozoites. After separation of the merozoites, residual bodies formed. The merogonic stages were differentiated into two forms, micromeront that measured 15.57×14.29 µm, and produces a few numbers of macromerozoites, meanwhile the macromeront measured 19×15.9 µm and produces up to six micromerozoites.

Contagious Yawning in African Elephants (Loxodonta africana): Responses to Other Elephants and Familiar Humans.

While spontaneous yawning is common across all vertebrate classes, contagious yawning is less common and has been observed only in a few species of social animals. Interspecific contagious yawning in response to yawning by humans has been observed only by chimpanzees and dogs. After confirming additional occurrences of intraspecific contagious yawning in a group of captive African elephants previously studied, we further investigated the potential for the same group of elephants to engage in interspecific contagious yawning with familiar human handlers. Ten captive African elephants, most of whom had been previously studied, were observed over 13 nights for evidence of intraspecific contagious yawning. Seven of these elephants were also involved in trials where familiar handlers performed staged yawns, as well as trials with staged non-yawning gapes, or trials with no yawns or gapes. Incorporating previously collected contagious yawning data, we describe nine instances of intraspecific contagious yawning in the elephants. Three of the seven elephants yawned contagiously in response to humans during the interspecific yawning trials. This is the first report of interspecific contagious yawning by elephants in response to yawns by familiar humans.

Taxonomic bias in amphibian research: Are researchers responding to conservation need?

Amphibians are very diverse, widely distributed, and the most endangered class of vertebrates. As with other taxa, effective conservation of amphibians needs to be supported by detailed scientific knowledge. However, species rich and broadly distributed taxa are typically characterized by high variability in research effort. Our objective was therefore to understand which factors (ecological and cultural) have led some amphibian species to be more researched than others. We used two proxies of research effort: i) the total number of articles on Web of Science (WoS) that mention the scientific name (or synonyms) of each species, and; ii) the number of conservation science articles on WoS that mention the scientific name (or synonyms) of each species. These measures were used as dependent variables in zero hurdle regression models with the aim of identifying the most important factors driving species-level knowledge production. Well researched species (generally, and for conservation) tend to have a longer history of scientific research, come from countries with high scientific capacity, have large body size, and to be present in man-made habitats. Endangered species tend to be less researched, generally and for conservation, possibly because they are often more difficult to study: many endangered amphibians are restricted to small, fragmented and remote habitats in countries with low scientific capacity. We conclude with a discussion of how taxonomic biases in research effort on amphibians can be addressed given the limited funds available for conservation research.

ERGO: Breaking Down the Wall between Human Health and Environmental Testing of Endocrine Disrupters.

ERGO (EndocRine Guideline Optimization) is the acronym of a European Union-funded research and innovation action, that aims to break down the wall between mammalian and non-mammalian vertebrate regulatory testing of endocrine disruptors (EDs), by identifying, developing and aligning thyroid-related biomarkers and endpoints (B/E) for the linkage of effects between vertebrate classes. To achieve this, an adverse outcome pathway (AOP) network covering various modes of thyroid hormone disruption (THD) in multiple vertebrate classes will be developed. The AOP development will be based on existing and new data from in vitro and in vivo experiments with fish, amphibians and mammals, using a battery of different THDs. This will provide the scientifically plausible and evidence-based foundation for the selection of B/E and assays in lower vertebrates, predictive of human health outcomes. These assays will be prioritized for validation at OECD (Organization for Economic Cooperation and Development) level. ERGO will re-think ED testing strategies from in silico methods to in vivo testing and develop, optimize and validate existing in vivo and early life-stage OECD guidelines, as well as new in vitro protocols for THD. This strategy will reduce requirements for animal testing by preventing duplication of testing in mammals and non-mammalian vertebrates and increase the screening capacity to enable more chemicals to be tested for ED properties.

A catalogue of the vertebrate fossil record from the Guadix-Baza Basin (SE Spain)

In this paper, a catalogue of the vertebrate content of the Guadix-Baza Basin is presented. A total of 93 localities have been reviewed, providing more than 300 vertebrate species. These localities have been included in 11 biochronological units, ranging in age from the late Miocene (MN 13) to the Middle Pleistocene (MmQ 4), including also two MN 10 localities. The best-represented epoch in the Guadix-Baza Basin is the Pliocene (MN 14 to MN 16), with 41 sites. This is followed by the Early Pleistocene (MN17 and MmQ1 to MmQ3) with 30 sites. The vertebrate classes represented in the basin are Actinopterygii, Amphibia, Aves, Reptilia and Mammalia, this last one being the best represented. Among mammals, small mammals are in their turn the most abundant, particularly rodents. The families Muridae and Arvicolidae dominate the rodent assemblages, murids being the dominant family in the late Miocene and early Pliocene, and arvicolids the most abundant group in the late Pliocene and Pleistocene.

Dynamic Corridor Illusion in Pigeons: Humanlike Pictorial Cue Precedence Over Motion Parallax Cue in Size Perception.

Depth information is necessary for perceiving the real size of objects at varying visual distances. To investigate to what extent this size constancy present in another vertebrate class, we addressed the two questions using pigeons: (a) whether pigeons see a corridor illusion based on size constancy and (b) whether pigeons prioritize pictorial cues over motion parallax cues for size constancy, like humans. We trained pigeons to classify target sizes on a corridor. In addition, we presented a dynamic version of corridor illusion in which the target and corridor moved side by side. Target speed was changed to manipulate motion parallax. With the static corridor, pigeons overestimated the target size when it was located higher, indicating that pigeons see a corridor illusion like humans. With the dynamic corridor, the pigeons overestimated the target size depending on target position, as in the static condition, but target speed did not affect their responses, indicating that the pictorial precedence also applies to pigeons. In a follow-up experiment using the same stimulus, we confirmed that humans perceive object size based on pictorial cues. These results suggest that size constancy characteristics are highly similar between pigeons and humans, despite the differences in their phylogeny and neural systems.

Spexin and a Novel Cichlid-Specific Spexin Paralog Both Inhibit FSH and LH Through a Specific Galanin Receptor (Galr2b) in Tilapia.

Spexin (SPX) is a 14 amino acid peptide hormone that has pleiotropic functions across vertebrates, one of which is involvement in the brain-pituitary-gonad axis of fish. SPX(1) has been identified in each class of vertebrates, and a second SPX (named SPX2) has been found in some non-mammalian species. We have cloned two spexin paralogs, designated as Spx1a and Spx1b, from Nile tilapia (Oreochromis niloticus) that have varying tissue distribution patterns. Spx1b is a novel peptide only identified in cichlid fish, and is more closely related to Spx1 than Spx2 homologs as supported by phylogenetic, synteny, and functional analyses. Kisspeptin, Spx, and galanin (Gal) peptides and their corresponding kiss receptors and Gal receptors (Galrs), respectively, are evolutionarily related. Cloning of six tilapia Galrs (Galr1a, Galr1b, Galr2a, Galr2b, Galr type 1, and Galr type 2) and subsequent in vitro second-messenger reporter assays for Gαs, Gαq, and Gαi suggests that Gal and Spx activate Galr1a/Galr2a and Galr2b, respectively. A decrease in plasma follicle stimulating hormone and luteinizing hormone concentrations was observed with injections of Spx1a or Spx1b in vivo. Additionally, application of Spx1a and Spx1b to pituitary slices decreased the firing rate of LH cells, suggesting that the peptides can act directly at the level of the pituitary. These data collectively suggest an inhibitory mechanism of action against the secretion of gonadotropins for a traditional and a novel spexin paralog in cichlid species.

Evolution of neural processing for visual perception in vertebrates.

Visual perception requires both visual information and attention. This review compares, across classes of vertebrates, the functional and anatomical characteristics of (a) the neural pathways that process visual information about objects, and (b) stimulus selection pathways that determine the objects to which an animal attends. Early in the evolution of vertebrate species, visual perception was dominated by information transmitted via the midbrain (retinotectal) visual pathway, and attention was probably controlled primarily by a selection network in the midbrain. In contrast, in primates, visual perception is dominated by information transmitted via the forebrain (retinogeniculate) visual pathway, and attention is mediated largely by networks in the forebrain. In birds and nonprimate mammals, both the retinotectal and retinogeniculate pathways contribute critically to visual information processing, and both midbrain and forebrain networks play important roles in controlling attention. The computations and processing strategies in birds and mammals share some strikingly similar characteristics despite over 300 million years of independent evolution and being implemented by distinct brain architectures. The similarity of these functional characteristics suggests that they provide valuable advantages to visual perception in advanced visual systems. A schema is proposed that describes the evolution of the pathways and computations that enable visual perception in vertebrate species.

Historical environmental stability drives discordant niche filling dynamics across phylogenetic scales

AbstractAimRegional diversity can increase owing to either the packing of species within regional niche space or the expansion of regional niche space. Yet, the primary factors dictating these dynamics remain poorly understood. Here, we assess the relative influence of current environmental conditions (net primary productivity, NPP) versus historic environmental stability over the Last Glacial Maximum on niche filling patterns of vertebrates (mammals, birds, amphibians and reptiles) in the Australian Wet Tropics (AWTs).LocationAustralian Wet Tropics.TaxonVertebrates (mammals, birds, amphibians and reptiles).MethodsWe measured patterns of niche filling (niche packing vs. niche expansion) as the standardized departure of observed functional diversity (FD) from its null expectation. We fitted spatial models for vertebrates, and for each constituent class (mammals, birds, amphibians and reptiles) separately, to evaluate the relative effects of NPP and environmental stability on species richness and niche filling patterns.ResultsHistorical environmental stability had a greater effect than NPP on species richness and niche filling patterns. However, the directionality of this effect depended on phylogenetic scale, with vertebrates exhibiting niche packing while each constituent class (except reptiles) exhibited niche expansion with increasing environmental stability.Main ConclusionIntra‐class competition presumably leads to niche differentiation and expansion, whereas the overlap of functional traits among species from different classes leads to niche packing. That environmental stability over millennia is associated with an expanding niche space across multiple vertebrate classes suggests that the accumulation of FD within communities requires long recovery times.