Prenatal post-implantation development of collared peccaries (Pecari tajacu Linnaeus, 1758).

Given the importance of information on intrauterine development in diagnosing anomalies in the gestational development of the species for the development of assisted reproduction technologies as well as understanding the autonomy and responsiveness of the newborn, the aim of the present study was to describe the external morphology of collared peccary conceptuses. For this study, two conceptuses were used per gestational age of 25-120 days post-copulation (dpc) and neonates with 145 dpc, totalling 22 animals. Females were euthanised, and embryos/foetuses were examined, measured, and photographed. During the first third of the gestational period (25-50 dpc, n = 8), a marked body curvature, brain vesicles, somites, internal organs, placid lens, auricular protrusion and limb buds are noted. In the second third of the gestational period (51-100 dpc, n = 10), foetuses lose their body curvature, displaying greater anatomical definition, including skeletal, external ears, nostrils, eyelids and tactile hair formation and cranial suture closure. In addition, dorsal scent gland and genital tubercle differentiation were visualized at 50 days post-copulation. In the third of the gestational period (101-145 dpc, n = 4), the organs become completely formed, alongside skin darkening, eyelid opening, dental eruption, dorsal odorous gland development, sexual organ externalization, and fanero attachment development. These data allowed for the construction of a prenatal growth curve, providing comparative anatomy information for ungulates and further contributing towards rational reproductive management and reproductive biotechnologies for this species.

Identification and characterisation of Gamma-herpesviruses in zoo artiodactyla.

BACKGROUND: Viruses within the γ-herpesviruses subfamily include the causative agents of Malignant Catarrhal Fever (MCF) in several species of the order Artiodactyla. MCF is a usually fatal lymphoproliferative disease affecting non-adapted host species. In adapted host species these viruses become latent and recrudesce and transmit during times of stress or immunosuppression. The undetected presence of MCF-causing viruses (MCFVs) is a risk to non-adapted hosts, especially within non-sympatric zoological collections. This study investigated the presence of MCFVs in six different zoological collections in the UK, to evaluate the presence of subclinical/latent MCFVs in carrier animals. METHODS: One-hundred and thirty eight samples belonging to 54 different species of Artiodactyla were tested by Consensus Pan-herpes PCR. The positive samples were sequenced and subjected to phylogenetic analyses to understand their own evolutionary relationships and those with their hosts. RESULTS: Twenty-five samples from 18 different species tested positive. All viruses but one clustered in the γ-herpesvirus family and within the Macavirus as well as the non-Macavirus groups (caprinae and alcelaphinae/hippotraginae clusters, respectively). A strong association between virus and host species was evident in the Macavirus group and clustering within the caprinae group indicated potential pathogenicity. CONCLUSION: This study shows the presence of pathogenic and non-pathogenic MCFVs, as well as other γ-herpesviruses, in Artiodactyla species of conservation importance and allowed the identification of new herpesviruses in some non-adapted species.

The virtual brain endocast of Trogosus (Mammalia, Tillodontia) and its relevance in understanding the extinction of archaic placental mammals.

After successfully diversifying during the Paleocene, the descendants of the first wave of mammals that survived the end-Cretaceous mass extinction waned throughout the Eocene. Competition with modern crown clades and intense climate fluctuations may have been part of the factors leading to the extinction of these archaic groups. Why these taxa went extinct has rarely been studied from the perspective of the nervous system. Here, we describe the first virtual endocasts for the archaic order Tillodontia. Three species from the middle Eocene of North America were analyzed: Trogosus hillsii, Trogosus grangeri, and Trogosus castoridens. We made morphological comparisons with the plaster endocast of another tillodont, Tillodon fodiens, as well as groups potentially related to Tillodontia: Pantodonta, Arctocyonidae, and Cimolesta. Trogosus shows very little inter-specific variation with the only potential difference being related to the fusion of the optic canal and sphenorbital fissure. Many ancestral features are displayed by Trogosus, including an exposed midbrain, small neocortex, orbitotemporal canal ventral to rhinal fissure, and a broad circular fissure. Potential characteristics that could unite Tillodontia with Pantodonta, and Arctocyonidae are the posterior position of cranial nerve V3 exit in relation to the cerebrum and the low degree of development of the subarcuate fossa. The presence of large olfactory bulbs and a relatively small neocortex are consistent with a terrestrial lifestyle. A relatively small neocortex may have put Trogosus at risk when competing with artiodactyls for potentially similar resources and avoiding predation from archaic carnivorans, both of which are known to have had larger relative brain and neocortex sizes in the Eocene. These factors may have possibly exacerbated the extinction of Tillodontia, which showed highly specialized morphologies despite the increase in climate fluctuations throughout the Eocene, before disappearing during the middle Eocene.

Bone Anatomy of the Thoracic Limb in the Common Hippopotamus (Hippopotamus amphibius) and White Rhinoceros (Ceratotherium simum)

SUMMARY: Although megaherbivores do not belong to the Brazilian fauna, they can be found in national zoos, which makes it important to know the anatomy of the locomotor apparatus to contribute to the clinical routine of zoos and veterinary rehabilitation centers. Thus, the aim of this study was to describe the anatomical structures of the thoracic limb bones in the common hippopotamus (Hippopotamus amphibius) and white rhinoceros (Ceratotherium simum) and to compare them with the bone structures described for other ungulates. The scapula had a triangular appearance in the common hippopotamus, whereas in the white rhinoceros it had a rectangular appearance. The acromion was observed only in the common hippopotamus scapula. The hippopotamus humerus did not have the intermediate tubercle, only the greater and lesser tubercles, unlike the rhinoceros which also has the intermediate tubercle. The two megamammals studied had an ulna not incorporated to the radius and seven carpal bones distributed in two bone rows. The common hippopotamus had four digits and four metacarpal bones, while the white rhino had three digits, hence three metacarpal bones. Although with some species-specific differences, the bone anatomy found in the studied megaherbivores was similar to that described for domestic ungulates, such as horses and cattle. The fact that the bones studied belong to articulated skeletons of the collection of the Museum of Anatomy made it difficult to identify some anatomical structures. This study can help veterinarians in bone health care, animal welfare and comfort of such species present in Brazilian zoological parks.

Aunque los megaherbívoros no pertenecen a la fauna brasileña, se pueden encontrar en zoológicos nacionales, lo que hace importante conocer la anatomía del aparato locomotor para contribuir a la rutina clínica de los zoológicos y de los centros de rehabilitación veterinaria. Por tanto, el objetivo de este estudio fue describir las estructuras anatómicas de los huesos de los miembros torácicos en el hipopótamo común (Hippopotamus amphibius) y el rinoceronte blanco (Ceratotherium simum) y compararlas con las estructuras óseas descritas para otros ungulados. La escápula tenía una apariencia triangular en el hipopótamo común, mientras que en el rinoceronte blanco tenía una apariencia rectangular. El acromion se observó sólo en la escápula del hipopótamo común. El húmero del hipopótamo no tenía el tubérculo intermedio, sólo los tubérculos mayor y menor, a diferencia del rinoceronte que también tiene el tubérculo intermedio. Los dos ejemplares de megamamíferos estudiados tenían una ulna no incorporada al radio y siete huesos del carpo distribuidos en dos filas óseas. En el hipopótamo común se observaron cuatro dedos y cuatro huesos metacarpianos, mientras que en el rinoceronte blanco se encontraron tres dedos, por lo tanto, tres huesos metacarpianos.A pesar de algunas diferencias específicas de cada especie, la anatomía ósea encontrada en los megaherbívoros estudiados fue similar a la descrita para los ungulados domésticos, tal como los caballos y el ganado. El hecho de que los huesos estudiados pertenezcan a esqueletos articulados de la colección del Museo de Anatomía dificultó la identificación de algunas estructuras anatómicas. Este estudio puede ayudar a los veterinarios en el cuidado de la salud ósea, el bienestar animal y el confort de las especies presentes en los parques zoológicos brasileños.

Drivers of the artiodactyl turnover in insular western Europe at the Eocene-Oligocene Transition.

Simultaneously investigating the effects of abiotic and biotic factors on diversity dynamics is essential to understand the evolutionary history of clades. The Grande Coupure corresponds to a major faunal turnover at the Eocene-Oligocene transition (EOT) (~34.1 to 33.55 Mya) and is defined in western Europe as an extinction of insular European mammals coupled with the arrival of crown clades from Asia. Here, we focused on the species-rich group of endemic European artiodactyls to determine the drivers of the Grande Coupure during the major environmental disruptions at the EOT. Using Bayesian birth-death models, we analyzed an original high-resolution fossil dataset (90 species, >2,100 occurrences) from southwestern France (Quercy area) and estimated the regional diversification and diversity dynamics of endemic and immigrant artiodactyls. We show that the endemic artiodactyl radiation was mainly related to the Eocene tropical conditions, combined with biotic controls on speciation and clade-related diversity dependence. We further highlight that the major environmental changes at the transition (77% of species became extinct) and the concurrent increase in seasonality in Europe during the Oligocene were likely the main drivers of their decline. Surprisingly, our results do not support the widely-held hypothesis of active competition between endemic and immigrant artiodactyls but rather suggest a passive or opportunistic replacement by immigrants, which is further supported by morphological clustering of specific ecological traits across the Eocene-Oligocene transition. Our analyses provide insights into the evolutionary and ecological processes driving the diversification and decline of mammalian clades during a major biological and climatic crisis.

Reinforcing the idea of an early dispersal of Hippopotamus amphibius in Europe: Restoration and multidisciplinary study of the skull from the Middle Pleistocene of Cava Montanari (Rome, central Italy).

A skull of Hippopotamus recovered from the area of Tor di Quinto, within the urban area of Rome (central Italy) is here redescribed. Despite being one of the most complete specimens of hippopotamuses of the European Pleistocene, the Tor di Quinto skull did not attract much research interest, due to long-standing uncertainties on its provenance. This work begun in 2021, when the skull was restored, within a large renovation project on the vertebrate exposed at the Earth Science University Museum of Sapienza University of Rome. Original sediments were found inside the cranial and mandible cavities during the restoration work, which were sampled for petrographic analyses. By combining a review of the old paleontological, archeological and geological literature published during the 19th and 20th century on the Rome basin and the correlation of these new sedimentological and petrographic information with the lithostratigraphic and synthemic units of the national geological cartography, we clarify that the Hippopotamus skull was most likely to have been collected from a quarry called Cava Montanari, from a formation dated between 560 and 460 ka. Morphological and biometric analyses clearly support an attribution of the Cava Montanari specimen to the extant species Hippopotamus amphibius. The reassessment of the stratigraphic and geological data on Cava Montanari implies that the studied specimen is the earliest confirmed occurrence of Hippopotamus amphibius in the European fossil record.

Pseudogenization of the Hair-Related Genes PADI3 and S100A3 in Cetaceans and Hippopotamus amphibius.

Hair-related genes in mammals play important roles in the development and maintenance of hair and other keratinous structures in mammals. The peptidyl arginine deiminase 3 (PADI3) gene encodes an enzyme that catalyzes the conversion of arginine residues to citrulline. The S100 calcium binding protein A3 (S100A3) gene encodes a protein that is highly expressed in the hair cuticle and contains arginine residues that are converted to citrullines by PADI enzymes. In this study, we investigated the pseudogenization events of PADI3 and S100A3 in cetaceans and Hippopotamus amphibius. We found that PADI3 underwent three independent pseudogenization events during cetacean evolution, in baleen whales, toothed cetaceans other than Physeter catodon, and P. catodon. Notably, the entire PADI3 gene is absent in the baleen whales. Pseudogenization of S100A3 occurred independently in cetaceans and H. amphibius. Interestingly, we found that in cetaceans S100A3 underwent pseudogenization before PADI3, suggesting that differential selection pressures were acting on the two genes. Our findings provide valuable insights into the molecular evolution of these genes in cetaceans and hippopotamuses, highlighting their importance for understanding the evolution of hair-related genes.

Human-hippo conflicts around Lake Tana Biosphere Reserve, Ethiopia: Vulnerability of hippopotamus in human-dominated landscape.

Currently, the demand of the human population for more land, water, and other natural resources from wildlife habitats is increasing all over the world. Such intense human pressure results in conflict with wildlife and the impacts affect both parties negatively. The human-hippo conflict poses a serious problem for both local farmers' livelihoods and hippo conservation. To date, the extent of human-hippo conflict is poorly documented in Ethiopia. Specifically, the extent of human-hippo conflicts around Lake Tana Biosphere Reserve (LTBR) is unknown. Therefore, this study aimed to investigate the extent of human-hippo conflict, and possible mitigation measures proposed by the local people around LTBR, Ethiopia. We conducted a questionnaire interview with the household head, the household head's wife, or other adults ≥ 18 years old. All respondents reported that crop damage was the main cause of human-hippo conflict around LTBR. Livestock grazing competition (17.4%) and human attack (19.5%) were also sources of conflicts in the region. Respondents claimed that hippos destroyed crops including maize (Zea mays), teff (Eragrostis teff), finger millet (Eleusine coracana), and rice (Oryza sativa). Most (91.2%) respondents claimed that the severity of crop damage caused by hippos was high in the region. Most respondents (range 90 to 93%) complained about high crop damage suggesting that hippos be eliminated from the region. Local people estimated that the population sizes of hippos comprise an average of 243 individuals; however, we counted 122 hippos during our boat survey in the area. The result of this study showed that human-hippo conflicts cause negative effects on both farmers' livelihood and hippo conservation in the region. To mitigate human-hippo conflict, we suggest that proper land use zonation systems around key areas, broad awareness creation among local people, and alternative crop production should be promoted around the LTBR.

Chewing, dentition and tooth wear in Hippopotamidae (Hippopotamus amphibius and Choeropsis liberiensis).

Among mammals, hippopotamids ('hippos') have been described as the species with the lowest chewing efficacy despite elaborate enamel folds on the occlusal surface or their cheek teeth, which was hypothesized to result from the lack of a grinding chewing motion. We investigated the chewing and dentition of the two extant hippo species, the common hippo (Hippopotamus amphibius) and the pygmy hippo (Choeropsis liberiensis), making (video) observations of live animals and gathering data on museum specimens (n = 86 H. amphibius and 26 C. liberiensis skulls). Hippos have a low degree of anisodonty (differences in width between maxillary and mandibular cheek teeth) and anisognathy (difference in width between the upper and the lower jaw), corresponding to a mainly orthal (up-and-down) chewing motion. The two hippo species differ slightly, but distinctively, in their anterior dental morphology and chewing mode. In both species, the canines do not completely prevent a lateral jaw movement but would, in theory, permit this movement until the mandibular canines get into contact with the maxillary protruding snout. This movement is only realized, to a small extent, in pygmy hippos, leaving distinct wear traces on their incisors and creating relatively wider wear facets on the maxillary canines. In common hippos, the interlocking upper and lower incisors prevent lateral jaw movement. Corresponding contact wear facets are evident on the medial aspect of the upper, and on the lateral aspect of the lower incisors-unless museal reconstructions mispositioned these teeth. If these facets are interpreted as an indication for a relic of a lateral jaw movement that was probably more prominent in hippo ancestors, i.e. if we assume that hippos evolved orthal chewing secondarily, several other characteristics of hippos can be explained, such as a low degree of hypsodonty (in the absence of distinct attrition due to a grinding chewing movement), a secondary loss of complexity in their enamel schmelzmuster, a secondary evolution of a wide mouth gape, a reduction in anisodonty compared to their ancestors, and the evolution of a bilaterally symmetrical ('trifoliate') enamel folding pattern on the molar occlusal surface from an ancestral bunoselenodont condition. As an underlying driving force, selection for intraspecific combat with canines and incisors, necessitating a wide gape and a rigid jaw, has been suggested.

Increase on environmental seasonality through the European Early Pleistocene inferred from dental enamel hypoplasia.

An in-depth study of the Early Pleistocene European remains of Hippopotamus has allowed the first detailed description of the incidence and types of dental alterations related to palaeopathologies and potentially linked to climatic and environmental factors. The results of a long-term qualitative and quantitative assessment highlight the importance of nutrient deficiencies on the development of dental enamel hypoplasia in Hippopotamus. Glacial cyclicity and the resulting changes in humidity and plant community structure conditioned the local environments critical for the survival of this taxon. Two main intervals of putative constrained nutritionally restrictions were detected at ca. 1.8 Ma and ca. 0.86 Ma (i.e., MIS63 and MIS21, respectively). Statistical comparisons show an increase in the frequency of dental hypoplasia between these two chronological periods, thus reinforcing the idea of increased seasonality in the circum-Mediterranean environments during the Early Pleistocene.

First identification and characterization of ovine gammaherpesvirus type 2 in horses and artiodactyla from an outbreak of malignant catarrhal fever in Mexico.

Ovine gammaherpesvirus 2 (OvHV-2), a member of the genus Macavirus, causes sheep-associated malignant catarrhal fever (SA-MCF), a fatal lymphoproliferative disease affecting a wide variety of ungulates in addition to horses. This study described an outbreak of SA-MCF in Mexico and the identification of the OvHV-2 virus in primary rabbit testis cultures through the generation of intranuclear inclusion bodies, syncytia, immunofluorescence (IF), immunocytochemistry (ICC), immunohistochemistry (IHC), endpoint polymerase chain reaction (PCR), and partial sequencing of the ORF75 gene. The animals involved in this outbreak showed mucogingival ulcers in the vestibule of the mouth and tongue, hypersalivation, corneal opacity, reduced food consumption, and weight loss of variable severity. These clinical signs and the histopathological findings suggested the diagnosis of SA-MCF. Buffy coat fractions from the anticoagulated blood samples of ill animals were collected and analyzed by PCR. Positive buffy coats were used to inoculate the primary cell cultures of rabbit testis to identify the virus. Small clusters of refractile cytomegalic cells, characteristic of viral cytopathic effects, were observed between 48 and 72 h post-infection. Furthermore, intranuclear acidophilic inclusion bodies (IBs) were identified in the inoculated primary culture cells, and the cytoplasm showed immunoreactivity with hyperimmune rabbit serum against OvHV-2. Moreover, in the liver histological sections from sick deer, immunoreactive juxtanuclear IBs were identified with the same rabbit hyperimmune serum. The obtained sequences were aligned with the OvHV-2 sequences reported in GenBank and revealed a nucleotide identity higher than 98%. Based on the evidence provided in this study, we conclude that the outbreak of SA-MCF in the municipality of Tequisquiapan in the state of Queretaro, Mexico, was caused by OvHV-2. This is the second study reporting that horses are susceptible to OvHV-2 infection and can develop SA-MCF. We identified for the first time in Mexico, the presence of OvHV-2 in buffy coats from horses and Artiodactyla.

Evolutionary conservation of an ancient retroviral gagpol gene in Artiodactyla.

The genomes of mammals contain fingerprints of past infections by ancient retroviruses that invaded the germline of their ancestors. Most of these endogenous retroviruses (ERVs) contain only remnants of the original retrovirus; however, on rare occasions, ERV genes can be co-opted for a beneficial host function. While most studies of co-opted ERVs have focused on envelope genes, including the syncytins that function in placentation, there are examples of co-opted gag genes including one we recently discovered in simian primates. Here, we searched for other intact gag genes in non-primate mammalian lineages. We began by examining the genomes of extant camel species, which represent a basal lineage in the order Artiodactyla. This identified a gagpol gene with a large open reading frame (ORF) (>3,500 bp) in the same orthologous location in Artiodactyla species but that is absent in other mammals. Thus, this ERV was fixed in the common ancestor of all Artiodactyla at least 64 million years ago. The amino acid sequence of this gene, termed ARTgagpol, contains recognizable matrix, capsid, nucleocapsid, and reverse transcriptase domains in ruminants, with an RNase H domain in camels and pigs. Phylogenetic analysis and structural prediction of its reverse transcriptase and RNase H domains groups ARTgagpol with gammaretroviruses. Transcriptomic analysis shows ARTgagpol expression in multiple tissues suggestive of a co-opted host function. These findings identify the oldest and largest ERV-derived gagpol gene with an intact ORF in mammals, an intriguing milestone in the co-evolution of mammals and retroviruses. IMPORTANCE Retroviruses are unique among viruses that infect animals as they integrate their reverse-transcribed double-stranded DNA into host chromosomes. When this happens in a germline cell, such as sperm, egg, or their precursors, the integrated retroviral copies can be passed on to the next generation as endogenous retroviruses (ERVs). On rare occasions, the genes of these ERVs can be domesticated by the host. In this study we used computational similarity searches to identify an ancient ERV with an intact viral gagpol gene in the genomes of camels that is also found in the same genomic location in other even-toed ungulates suggesting that it is at least 64 million years old. Broad tissue expression and predicted preservation of the reverse transcriptase fold of this protein suggest that it may be domesticated for a host function. This is the oldest known intact gagpol gene of an ancient retrovirus in mammals.

Genetic diversity and relatedness in captive collared peccaries Dicotyles tajacu (Linnaeus, 1758) (Cetartiodactyla: Tayassuidae) estimated by microsatellite genotyping using high-throughput sequencing: Implications for their conservation and reintroduction.

The global population of Dicotyles tajacu (Linnaeus, 1758) (Cetartiodactyla: Tayassuidae), commonly known as the collared peccary and distributed in the Neotropics, is currently in decline due to anthropogenic pressures. In this study, five microsatellite loci were used to genetically characterize a group of 20 captive-born collared peccaries intended for reintroduction. This study aimed to evaluate the genetic diversity and relatedness of captive individuals using microsatellite markers. The genetic data generated were used to evaluate the viability of the reintroduction and to propose measures for the management and conservation of this species. In this study, we found relatively high genetic diversity indices, indicating that the group was genetically diverse. Inbreeding coefficients with negative values were observed, indicating an excess of alleles in heterozygosis and an absence of inbreeding. One locus showed deviation from Hardy-Weinberg equilibrium, which may have been caused by the mixing of individuals from different origins. Relatedness analysis indicated that some individuals were highly related, with coefficients indicating they may be first-degree relatives. Our findings indicate that the studied group has enough genetic diversity to be released into nature, but the high individual relatedness found would require the adoption of strategies after the release of animals in the wild to ensure their persistence.

A systematic review of the microbial community in taiassuids: a One Health approach.

Collared and white-lipped peccaries are sympatric and are distributed in most of South America and in the humid tropical forests of Mexico and Central America. Historically, these species have been used as a source of protein by traditional and/or indigenous human communities, but currently they have been used for legal consumption in different countries. Thus, there has been greater interaction between these wild species and domestic animals and humans, enabling microbial interactions between different niches. The present study presents a systematic review of the literature on the microbial community of collared peccaries and white-lipped peccaries distributed throughout the world, focusing on experimental studies related to the detection of microorganisms as well as the prevalence of the animal species and its characterization of the studied population, in situ or ex situ. Seventy-two studies were selected, mainly in South American countries, related to different species of microorganisms isolated or serologically detected (viruses, bacteria, fungi, and parasites), either as microbiota, pathogens or commensals, many of which are of zoonotic interest, such as Leptospira, Toxoplasma, Brucella, among others. Therefore, these wild mammals are characterized as sentinel agents of anthropic action and require the implementation of studies in relation to their contribution to the spread of microorganisms, being a potential source of amplification and transmission of pathogens.

Non-invasive assessment of fecal glucocorticoid and androgen metabolites in the pygmy hippopotamus (Choeropsis liberiensis).

The pygmy hippopotamus (Choeropsis liberiensis) is an endangered species endemic to the Upper Guinea Forest ecosystem in West Africa. We have limited information concerning the species' reproduction and well-being under managed care. We therefore developed non-invasive methods for characterizing gonadal androgen and adrenal hormone profiles in pygmy hippos using fecal samples collected from 12 males and 12 females housed in North American zoological institutions. We aimed to: 1) identify and validate enzyme immunoassays (EIAs) for measuring metabolites of corticosteroids and testosterone in feces; and 2) test whether gonadal activity is correlated with previous breeding history, season or type of housing. For glucocorticoids, several EIAs for measuring metabolites were investigated. A group-specific EIA exhibiting cross-reactivity with 11,17-dioxoandrostane (DOA) metabolites of cortisol most clearly reflected adrenocortical activity in response to pharmocological challenge with adrenocorticotropic hormone (ACTH) in both males and females. However, day-to-day concentrations of this metabolite in the feces of pygmy hippos that did not undergo ACTH challenge were near the detection limits of the assay, making this EIA impractical for assessing glucocorticoid activity in this species. Another group-specific EIA, exhibiting cross-reactivity with 5α-pregnane-3ß,11ß,21-triol-20-one, produced biologically relevant data and evidence of an appropriate response to pharmacological challenge with exogenous ACTH. The testosterone metabolite assay C196 (Arbor Assays, Ann Arbor, Michigan, USA) also produced biologically coherent data: adult males exhibited the highest mean androgen metabolite concentrations (477 ng/g), followed by adult females (259 ng/g) and juvenile males (160 ng/g). Proven breeding males had higher, but not significantly different, mean concentrations (472 ng/g) to unproven males (352 ng/g; P = 0.400). Similarly, adult males housed outdoors year-round in subtropical climates exhibited higher, but not statistically different mean concentrations (554 ng/g) to males in temperate climates that were housed indoors at least part of the year (412 ng/g; P = 0.208). There were, however, significant differences in mean concentrations among seasons for adult males, with higher values in spring (546 ng/g) and summer (542 ng/g) than in autumn (426 ng/g) and winter (388 ng/g, P = 0.003). In conclusion, we identified EIAs for the measurement of fecal metabolites of androgens and glucocorticoids that can be used for further studies to monitor gonadal activity in male pygmy hippos and adrenocortical activity in both sexes. We also identified a seasonal trend in male gonadal activity in this species under managed care in North America. Finally, our findings highlight an important consideration when using non-invasive methods for evaluating fecal cortisol metabolites: ACTH used for pharmacological validation of an EIA does not necessarily equate to biological relevance.

Evolution and development of the cetacean skull roof: a case study in novelty and homology.

Skulls of living whales and dolphins (cetaceans) are telescoped-bones of the skull roof are overlapped by expanded facial bones and/or anteriorly extended occipital bones. Evolution of the underlying skull roof (calvarium), which lies between the telescoped regions, is relatively unstudied. We explore the evolution and development of the calvarium of toothed whales (odontocetes) by integrating fetal data with Oligocene odontocete fossils from North America, including eight neonatal and juvenile skulls of Olympicetus†. We identified two potential synapomorphies of crown Cetacea: contact of interparietals with frontals, and a single anterior median interparietal (AMI) element. Within Odontoceti, loss of contact between the parietals diagnoses the clade including Delphinida, Ziphiidae and Platanistidae (=Synrhina). Delphinida is characterized by a greatly enlarged interparietal. New fetal series of delphinoids reveal a consistent developmental pattern with three elements: the AMI and bilateral posterior interparietals (PIs). The PIs most resemble the medial interparietal elements of terrestrial artiodactyls, suggesting that the AMI of cetaceans could be a unique ossification. More broadly, the paucity of conserved anatomical relationships of the interparietals, as well as the fact that the elements often do not coalesce into a single bone, demonstrates that assessing homology of the interparietals across mammals remains challenging. This article is part of the theme issue 'The mammalian skull: development, structure and function'.

Are hippos Africa's most influential megaherbivore? A review of ecosystem engineering by the semi-aquatic common hippopotamus.

Megaherbivores perform vital ecosystem engineering roles, and have their last remaining stronghold in Africa. Of Africa's remaining megaherbivores, the common hippopotamus (Hippopotamus amphibius) has received the least scientific and conservation attention, despite how influential their ecosystem engineering activities appear to be. Given the potentially crucial ecosystem engineering influence of hippos, as well as mounting conservation concerns threatening their long-term persistence, a review of the evidence for hippos being ecosystem engineers, and the effects of their engineering, is both timely and necessary. In this review, we assess, (i) aspects of hippo biology that underlie their unique ecosystem engineering potential; (ii) evaluate hippo ecological impacts in terrestrial and aquatic environments; (iii) compare the ecosystem engineering influence of hippos to other extant African megaherbivores; (iv) evaluate factors most critical to hippo conservation and ecosystem engineering; and (v) highlight future research directions and challenges that may yield new insights into the ecological role of hippos, and of megaherbivores more broadly. We find that a variety of key life-history traits determine the hippo's unique influence, including their semi-aquatic lifestyle, large body size, specialised gut anatomy, muzzle structure, small and partially webbed feet, and highly gregarious nature. On land, hippos create grazing lawns that contain distinct plant communities and alter fire spatial extent, which shapes woody plant demographics and might assist in maintaining fire-sensitive riverine vegetation. In water, hippos deposit nutrient-rich dung, stimulating aquatic food chains and altering water chemistry and quality, impacting a host of different organisms. Hippo trampling and wallowing alters geomorphological processes, widening riverbanks, creating new river channels, and forming gullies along well-utilised hippo paths. Taken together, we propose that these myriad impacts combine to make hippos Africa's most influential megaherbivore, specifically because of the high diversity and intensity of their ecological impacts compared with other megaherbivores, and because of their unique capacity to transfer nutrients across ecosystem boundaries, enriching both terrestrial and aquatic ecosystems. Nonetheless, water pollution and extraction for agriculture and industry, erratic rainfall patterns and human-hippo conflict, threaten hippo ecosystem engineering and persistence. Therefore, we encourage greater consideration of the unique role of hippos as ecosystem engineers when considering the functional importance of megafauna in African ecosystems, and increased attention to declining hippo habitat and populations, which if unchecked could change the way in which many African ecosystems function.

A quantum leap in the evolution of platyhelminths: Host-switching from turtles to hippopotamuses illustrated from a phylogenetic meta-analysis of polystomes (Monogenea, Polystomatidae).

While monogenean worms are mainly parasites of the gills and skin of fish, and to a lesser extent parasites of the oral cavity, urinary bladder, and/or conjunctival sacs of amphibians and freshwater turtles, Oculotrema hippopotamiStunkard, 1924 is the single monogenean polystome reported from a mammal, the common hippopotamus (Hippopotamus amphibius Linnaeus). Several hypotheses have been suggested in the last decade to explain the origin of this enigmatic parasite which infects the conjunctival sacs of H. amphibius. Based on a molecular phylogeny inferred from nuclear (28S and 18S) and mitochondrial (12S and COI) sequences of O. hippopotami and chelonian polystomes, we found a sister group relationship between O. hippopotami and Apaloneotrema moleri (Du Preez & Morrison, 2012). This result suggests lateral parasite transfer between freshwater turtles and hippopotamuses, thus likely reflecting one of the most exceptional known examples of host-switching in the course of vertebrate evolution. It also demonstrates that the proximity in the ecological habitat of parasites within host species is an important feature for their speciation and diversification. Because A. moleri and its host, the Florida softshell turtle (Apalone ferox (Schneider)), are restricted to the USA, we suggest that an ancestral stock of parasites may have been isolated on primitive African trionychids after they diverged from their American relatives, and then switched to hippopotamuses or anthracotheres in Africa.

EVALUATION OF A COMBINATION OF TILETAMINE-ZOLAZEPAM, MEDETOMIDINE, AND AZAPERONE WITH NASAL OXYGEN SUPPLEMENTATION FOR THE IMMOBILIZATION OF CAPTIVE CHACOAN PECCARIES (CATAGONUS WAGNERI) IN THE CHACO REGION OF PARAGUAY.

A combination of tiletamine-zolazepam, medetomidine, and azaperone was used to immobilize captive Chacoan peccaries (Catagonus wagneri) for health assessments and biological sample collection at the Centro Chaqueño para la Conservación e Investigación (CCCI) in the Paraguayan Chaco during July in 2017 and 2018. In total, 83 peccaries kept in 0.25-1.50 hectare enclosures were immobilized via dart-administered anesthetic. Mean animal weight was 33.89±3.74 kg (standard deviation; n=77). The mean intramuscular (IM) anesthetic drug and dosages were 0.03±0.00 mg/kg of medetomidine, 0.91±0.10 mg/kg of Zoletil 50 (tiletamine-zolazepam), and 0.30±0.03 mg/kg azaperone. The mean time to recumbency after darting was 6.07±2.65 min. The mean time to reach the anesthetic plane postdarting was 10.00±2.00 min. Muscle relaxation was adequate to allow minor veterinary procedures. A mean dosage of 0.15±0.02 mg/kg of atipamezole was given IM to reverse the medetomidine. Recoveries were smooth and animals were standing by 59.17±30.18 min postreversal. Full recovery and release back to enclosures occurred 90±30 min postreversal. A single dose of this drug combination provided adequate anesthesia for 88% of adult Chacoan peccaries; 12% needed a supplemental dose of tiletamine-zolazepam because of failure to receive the full dose from the anesthetic dart. Sex and age did not impact the dosage required to achieve immobilization. Confinement during recovery from anesthesia is required with this protocol. Aside from mild hypoxemia, no adverse effects from anesthesia were observed. However, oxygen supplementation as a part of this protocol is recommended to support circulatory and respiratory capacity.