Molecular basis of hippopotamus ACE2 binding to SARS-CoV-2.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has a wide range of hosts, including hippopotami, which are semi-aquatic mammals and phylogenetically closely related to Cetacea. In this study, we characterized the binding properties of hippopotamus angiotensin-converting enzyme 2 (hiACE2) to the spike (S) protein receptor binding domains (RBDs) of the SARS-CoV-2 prototype (PT) and variants of concern (VOCs). Furthermore, the cryo-electron microscopy (cryo-EM) structure of the SARS-CoV-2 PT S protein complexed with hiACE2 was resolved. Structural and mutational analyses revealed that L30 and F83, which are specific to hiACE2, played a crucial role in the hiACE2/SARS-CoV-2 RBD interaction. In addition, comparative and structural analysis of ACE2 orthologs suggested that the cetaceans may have the potential to be infected by SARS-CoV-2. These results provide crucial molecular insights into the susceptibility of hippopotami to SARS-CoV-2 and suggest the potential risk of SARS-CoV-2 VOCs spillover and the necessity for surveillance. IMPORTANCE: The hippopotami are the first semi-aquatic artiodactyl mammals wherein SARS-CoV-2 infection has been reported. Exploration of the invasion mechanism of SARS-CoV-2 will provide important information for the surveillance of SARS-CoV-2 in hippopotami, as well as other semi-aquatic mammals and cetaceans. Here, we found that hippopotamus ACE2 (hiACE2) could efficiently bind to the RBDs of the SARS-CoV-2 prototype (PT) and variants of concern (VOCs) and facilitate the transduction of SARS-CoV-2 PT and VOCs pseudoviruses into hiACE2-expressing cells. The cryo-EM structure of the SARS-CoV-2 PT S protein complexed with hiACE2 elucidated a few critical residues in the RBD/hiACE2 interface, especially L30 and F83 of hiACE2 which are unique to hiACE2 and contributed to the decreased binding affinity to PT RBD compared to human ACE2. Our work provides insight into cross-species transmission and highlights the necessity for monitoring host jumps and spillover events on SARS-CoV-2 in semi-aquatic/aquatic mammals.

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.

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.

SARS-CoV-2 Infection in a Hippopotamus, Hanoi, Vietnam.

While investigating the death of a hippopotamus at a zoo in Hanoi, Vietnam, we isolated SARS-CoV-2 and sequenced the RNA-dependent RNA polymerase gene from different organs. Phylogenetic analysis showed that the SARS-CoV-2 strain was closely related to 3 human SARS-CoV-2 strains in Vietnam.

Paleobiogeographical origins of Fasciola hepatica and F. gigantica in light of new DNA sequence characteristics of F. nyanzae from hippopotamus.

Fascioliasis is a highly pathogenic disease affecting humans and livestock worldwide. It is caused by the liver flukes Fasciola hepatica transmitted by Galba/Fossaria lymnaeid snails in Europe, Asia, Africa, the Americas and Oceania, and F. gigantica transmitted by Radix lymnaeids in Africa and Asia. An evident founder effect appears in genetic studies as the consequence of their spread by human-guided movements of domestic ruminants, equines and Old World camelids in the post-domestication period from the beginning of the Neolithic. Establishing the geographical origins of fasciolid expansion is multidisciplinary crucial for disease assessment. Sequencing of selected nuclear ribosomal and mitochondrial DNA markers of F. nyanzae infecting hippopotamuses (Hippopotamus amphibius) in South Africa and their comparative analyses with F. hepatica and F. gigantica, and the two Fascioloides species, Fs. jacksoni from Asian elephants and Fs. magna from Holarctic cervids, allow to draw a tuned-up evolutionary scenario during the pre-domestication period. Close sequence similarities indicate a direct derivation of F. hepatica and F. gigantica from F. nyanzae by speciation after host capture phenomena. Phylogenetic reconstruction, genetic distances and divergence estimates fully fit fossil knowledge, past interconnecting bridges between continents, present fasciolid infection in the wild fauna, and lymnaeid distribution. The paleobiogeographical analyses suggest an origin for F. gigantica by transfer from primitive hippopotamuses to grazing bovid ancestors of Reduncinae, Bovinae and Alcelaphinae, by keeping the same vector Radix natalensis in warm lowlands of southeastern Africa in the mid-Miocene, around 13.5 mya. The origin of F. hepatica should have occurred after capture from primitive, less amphibious Hexaprotodon hippopotamuses to mid-sized ovicaprines as the wild bezoar Capra aegagrus and the wild mouflon Ovis gmelini, and from R. natalensis to Galba truncatula in cooler areas and mountainous foothills of Asian Near East in the latest Miocene to Early Pliocene, around 6.0 to 4.0 mya and perhaps shortly afterwards.

Biological characteristics of two mesenchymal stem cell cultures isolated from the umbilical cord and adipose tissue of a neonatal common hippo (Hippopotamus amphibius).

Mesenchymal stem cells (MSCs) are multipotent adult stem cells and can be isolated from many tissues of the body. Due to their potentials to treat various diseases and be applied in animal breeding, MSCs have been isolated and identified regarding their biological properties. Common hippos (Hippopotamus amphibius) are a vulnerable species and yet the cryopreservation of their genetic materials is scare. In this study, we successfully established two MSC cultures (UC-MSCs and AT-MSCs) from the umbilical cord and adipose tissue of a neonatal common hippo and comparatively described their features. Both UC-MSCs and AT-MSCs showed fibroblastoid morphology and could be continuously passaged for over 17 passages without dramatic signs of senescence. The cell cultures had normal chromosome composition, say, 17 pairs of autosomes and 1 pair of X chromosomes. UC-MSCs and AT-MSCs displayed similar gene expression profiles. They were positive for CD34, CD45, CD73, CD90 and CD105 and negative for HLA-DR. They demonstrated stemness maintenance by expression of classical stem cell markers. UC-MSCs and AT-MSCs manifested different differentiation potentials into other cell lineages. In summary, these two cell cultures demonstrated the essential properties of mesenchymal stem cells and might play a role in the future research.

Dietary isotopes of Madagascar's extinct megafauna reveal holocene browsing and grazing guilds.

Megafauna play a disproportionate role in developing and maintaining their biomes, by regulating plant dispersal, community structure and nutrient cycling. Understanding the ecological roles of extinct megafaunal communities, for example through dietary reconstruction using isotope analysis, is necessary to determine pre-human states and set evidence-based restoration goals. We use δ13C and δ15N isotopic analyses to reconstruct Holocene feeding guilds in Madagascar's extinct megaherbivores, which included elephant birds, hippopotami and giant tortoises that occurred across multiple habitats and elevations. We compare isotopic data from seven taxa and two elephant bird eggshell morphotypes against contemporary regional floral baselines to infer dietary subsistence strategies. Most taxa show high consumption of C3 and/or CAM plants, providing evidence of widespread browsing ecology. However, Aepyornis hildebrandti, an elephant bird restricted to the central highlands region, has isotope values with much higher δ13C values than other taxa. This species is interpreted as having obtained up to 48% of its diet from C4 grasses. These findings provide new evidence for distinct browsing and grazing guilds in Madagascar's Holocene megaherbivore fauna, with implications for past regional distribution of ecosystems dominated by endemic C4 grasses.

Challenges of devising a milk recipe in a hand-reared hippopotamus (Hippopotamus amphibius).

In January 2017, a Nile hippopotamus (Hippopotamus amphibious) was born approximately six weeks premature at the Cincinnati Zoo & Botanical Garden. Due to the calf's weakened condition and lack of interest from the dam, management at the zoo made the decision to hand-rear the calf. Limited published information was available on hand-rearing this species of hippopotamus (hippo). To devise a nutritionally appropriate recipe, milk samples were acquired from the dam on Days 1, 3, 8, and 9 postpartum, and assayed for sugar, protein, fat, mineral, and water content using standard methods validated for multiple species of mammals at the Smithsonian National Zoo's Nutrition Science Laboratory. The sugar content stayed relatively constant (mean = 4.5%; range: 4.3%-4.7%). The fat consistently increased from 0.48% to 4.24% (mean = 2%). Excluding Day 9, the protein content gradually decreased from 9.56% to 6.39% (mean = 8%). The dry matter (DM) ranged from 14.38% to 16.72% (i.e., water content of 85.62%-83.28%), with the sum of the solids (sugar, protein, fat, and ash) averaging 98.5% of measured DM. Fat content was lower than expected but within the range of other artiodactyls. Between Days 1 and 8, the trend of decreasing protein and increasing fat was consistent with a change from colostrum to mature milk. The sharp increase in fat and protein with a decrease in sugar on Day 9 may indicate the beginning of the involution of the mammary gland due to lack of nursing stimulus. Utilizing this information, the Cincinnati Zoo was able to formulate a successful milk replacement recipe that allowed the calf to be raised through weaning to maturity.

Diagnosis of Mycobacterium bovis infection in free-ranging common hippopotamus (Hippopotamus amphibius).

Bovine tuberculosis (bTB), caused by Mycobacterium bovis (M. bovis) infection, is a multi-host disease which negatively affects the wildlife industry, with adverse consequences for conservation, ecotourism, and game/wildlife sales. Although interspecies transmission has been reported between some wildlife hosts, the risk of spread in complex ecosystems is largely unknown. As a controlled disease, tools for accurate detection of M. bovis infection are crucial for effective surveillance and management, especially in wildlife populations. There are, however, limited species-specific diagnostic tests available for wildlife. Hippopotamuses are rarely tested for M. bovis infection, and infection has not previously been confirmed in these species. In this study, blood and tissue samples collected from common hippopotamus (Hippopotamus amphibius) residing in a bTB-endemic area, the Greater Kruger Protected area (GKPA), were retrospectively screened to determine whether there was evidence for interspecies transmission of M. bovis, and identify tools for M. bovis detection in this species. Using the multi-species DPP® VetTB serological assay, a bTB seroprevalence of 8% was found in hippopotamus from GKPA. In addition, the first confirmed case of M. bovis infection in a free-ranging common hippopotamus is reported, based on the isolation in mycobacterial culture, genetic speciation and detection of DNA in tissue samples. Importantly, the M. bovis spoligotype (SB0121) isolated from this common hippopotamus is shared with other M. bovis-infected hosts in GKPA, suggesting interspecies transmission. These results support the hypothesis that M. bovis infection may be under recognized in hippopotamus. Further investigation is needed to determine the risk of interspecies transmission of M. bovis to common hippopotamus in bTB-endemic ecosystems and evaluate serological and other diagnostic tools in this species.

Contrasting selection pressure on body and weapon size in a polygynous megaherbivore.

Sexual size dimorphism (SSD) is a common morphological trait in ungulates, with polygyny considered the leading driver of larger male body mass and weapon size. However, not all polygynous species exhibit SSD, while molecular evidence has revealed a more complex relationship between paternity and mating system than originally predicted. SSD is, therefore, likely to be shaped by a range of social, ecological and physiological factors. We present the first definitive analysis of SSD in the common hippopotamus (Hippopotamus amphibius) using a unique morphological dataset collected from 2994 aged individuals. The results confirm that hippos exhibit SSD, but the mean body mass differed by only 5% between the sexes, which is rather limited compared with many other polygynous ungulates. However, jaw and canine mass are significantly greater in males than females (44% and 81% heavier, respectively), highlighting the considerable selection pressure for acquiring larger weapons. A predominantly aquatic lifestyle coupled with the physiological limitations of their foregut fermenting morphology likely restricts body size differences between the sexes. Indeed, hippos appear to be a rare example among ungulates whereby sexual selection favours increased weapon size over body mass, underlining the important role that species-specific ecology and physiology have in shaping SSD.

Establishment and characterization of fibroblast cultures derived from a female common hippopotamus (Hippopotamus amphibius) skin biopsy.

The population decline of the common hippopotamus (Hippopotamus amphibius) has necessitated the preservation of their genetic resources for species conservation and research. Of all actions, cryopreservation of fibroblast cell cultures derived from an animal biopsy is considered a simple but efficient means. Nevertheless, preserving viable cell cultures of the common hippopotamus has not been achieved to our knowledge. To this end, we established and characterized fibroblast cell cultures from the skin sample of a newborn common hippopotamus in this study. By combining the tissue explant direct culture and enzymatic digestion methods, we isolated a great number of cells with typical fibroblastic morphology and high viability. Neither bacteria/fungi nor mycoplasma was detectable in the cell cultures throughout the study. The population doubling time was 34 h according to the growth curve. Karyotyping based on Giemsa staining showed that the cultured cells were diploid with 36 chromosomes in all, one pair of which was sex chromosomes. The amplified mitochondrial cytochrome C oxidase subunit I gene sequence of the cultured cells was 99.26% identical with that of the registered H. amphibius complete mitochondrial DNA, confirming the species of origin of the cells. Flow cytometry and immunofluorescence staining results revealed that the detected cells were positive for fibroblast markers, S100A4, and vimentin. In conclusion, we generated the fibroblast cell cultures from a common hippopotamus and identified their characteristics using multiple techniques. We believe the cryopreserved cells could be useful genetic materials for future research.

Gross anatomy, histological, and histochemical analysis of the eyelids and orbital glands of the neonate pygmy hippopotamus (Suina: Choeropsis liberiensis or Hexaprotodon liberiensis, Morton 1849) with reference to its habitat.

The pygmy hippopotamus is phylogenetically related to members of both the Suidae and Cetacea. However, differences in their habitats may have resulted in variation in the anatomy and physiology of the ocular adnexa between these species. Therefore, this study focuses on the identification of accessory organs of the eye, which are typical for the pygmy hippopotamus and are comparable to organs present in mammals related to it. Moreover, the secretions produced by the superficial gland of the third eyelid, the deep gland of the third eyelid and the lacrimal gland were examined, as they ensure eyeball protection. In the upper and lower eyelids, numerous serous glands where identified, which were typical for the pygmy hippopotamus and similar as in the Cetacea. This study enabled to identify additional folds in the eyelids of the pygmy hippopotamus. Lymphoid follicles and diffuse lymphocytes were not found in the lymphoid region in the upper or lower eyelids and the third eyelid, which was most likely caused by the age of the studied hippopotamuses. An accurate histochemical analysis revealed that the secretions of the pygmy hippopotamus are very similar to the Sus scrofa. The structural differences between the pygmy hippopotamus and representatives of Cetacea are most likely caused by the fact that most of Cetacea live in saltwater and are exposed to more frequent fluctuations in water temperature compared to the pygmy hippopotamus, which lives in fresh water and does not lead a migratory lifestyle like the Cetacea.

Hippopotamus are distinct from domestic livestock in their resource subsidies to and effects on aquatic ecosystems.

In many regions of the world, populations of large wildlife have been displaced by livestock, and this may change the functioning of aquatic ecosystems owing to significant differences in the quantity and quality of their dung. We developed a model for estimating loading rates of organic matter (dung) by cattle for comparison with estimated rates for hippopotamus in the Mara River, Kenya. We then conducted a replicated mesocosm experiment to measure ecosystem effects of nutrient and carbon inputs associated with dung from livestock (cattle) versus large wildlife (hippopotamus). Our loading model shows that per capita dung input by cattle is lower than for hippos, but total dung inputs by cattle constitute a significant portion of loading from large herbivores owing to the large numbers of cattle on the landscape. Cattle dung transfers higher amounts of limiting nutrients, major ions and dissolved organic carbon to aquatic ecosystems relative to hippo dung, and gross primary production and microbial biomass were higher in cattle dung treatments than in hippo dung treatments. Our results demonstrate that different forms of animal dung may influence aquatic ecosystems in fundamentally different ways when introduced into aquatic ecosystems as a terrestrially derived resource subsidy.

Ecosystem effects of the world's largest invasive animal.

The keystone roles of mega-fauna in many terrestrial ecosystems have been lost to defaunation. Large predators and herbivores often play keystone roles in their native ranges, and some have established invasive populations in new biogeographic regions. However, few empirical examples are available to guide expectations about how mega-fauna affect ecosystems in novel environmental and evolutionary contexts. We examined the impacts on aquatic ecosystems of an emerging population of hippopotamus (Hippopotamus amphibus) that has been growing in Colombia over the last 25 yr. Hippos in Africa fertilize lakes and rivers by grazing on land and excreting wastes in the water. Stable isotopes indicate that terrestrial sources contribute more carbon in Colombian lakes containing hippo populations, and daily dissolved oxygen cycles suggest that their presence stimulates ecosystem metabolism. Phytoplankton communities were more dominated by cyanobacteria in lakes with hippos, and bacteria, zooplankton, and benthic invertebrate communities were similar regardless of hippo presence. Our results suggest that hippos recapitulate their role as ecosystem engineers in Colombia, importing terrestrial organic matter and nutrients with detectable impacts on ecosystem metabolism and community structure in the early stages of invasion. Ongoing range expansion may pose a threat to water resources.

Three-dimensional CT examination of the forefoot and hindfoot of the hippopotamus and tapir during a semiaquatic walking.

Semiaquatic walking has resulted in the evolution of functional and morphological changes in various hoofed mammals, such as hippopotamus and Brazilian tapir. The biomechanics of skilful walking in wetlands or at the bottom of a waterbody involve the medio-lateral opening and closing of the feet to effectively support and stabilize the body on soft ground and to reduce the water resistance during recovery stroke, respectively. We demonstrate that the opening and closing of the feet in hippopotamus and Brazilian tapir are mediated by the adduction and abduction of the most medial and lateral phalanges from the CT examination. The axial toes, metacarpals and metatarsals do not contribute to changes in the width and shape of the feet, unlike the medial and lateral toes. We suggest that this semiaquatic walking motion is derived from the original terrestrial mode of locomotion, in contrast to the highly functional swimming motion using webs or fins in morphologically modified feet and tail. From the present data we demonstrate that semiaquatic locomotion evolved due to the acquisition of adductor-abductor mobility in the phalanges of the most medial and lateral digits, as shown in hippopotamus and Brazilian tapir.

A Comparison of Common Hippopotamus (Artiodactyla) and Mysticete (Cetacea) Nostrils: An Open and Shut Case.

Hippos are considered the closest living relatives to cetaceans and they have some similar adaptations for aquatic living, such as a modified respiratory tract. Behavioral observations of male and female common hippos (Hippopotamus amphibius) at Disney's Animal Kingdom® and the Adventure Aquarium were conducted to describe and examine movements of the nostrils during respiration (inspiration, expiration, and inter-breath interval). The hippo nostril is a crescent shaped opening with lateral and medial aspects that are mobile and can be adducted and abducted to regulate the nostril opening. Notably, the default (resting) position of the nostrils is closed during the inter-breath interval, even when hippos are resting in water and their heads are not submerged. Similar to cetaceans, this aquatic adaptation protects the respiratory tract from an accidental incursion of water that can occur even when the nostrils are above water. Dissection of a deceased captive common hippo suggests there are separate muscles that pull the medial and lateral aspects for abduction. The internal nasal passage has a nasal plug that is similar in shape but less pronounced than the nasal plugs of two baleen whale species studied (minke whale Balaenoptera acutorostrata, fin whale Balaenoptera physalus). Examination of the musculature suggests fibers attach from the premaxillae and extend caudally to retract the plug to open the nasal passage. We discuss similarities and differences of the nostrils/blowholes of fully aquatic, semi-aquatic, and terrestrial species to assess adaptations related to environmental conditions that may be convergent or derived from a common ancestor. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc. Anat Rec, 302:693-702, 2019. © 2018 Wiley Periodicals, Inc.

Estado actual de los hipopótamos (Hippopotamus amphibius) en Colombia: 2018

En el año 1985, el narcotraficante Pablo Escobar ingresó a Colombia entre dos y seis ejemplares juveniles de hipopótamos que, con el paso de dos décadas, se reprodujeron y movilizaron por la zona geográfica del Magdalena Medio. En la actualidad se cree que podría haber entre diez y treinta ejemplares libres en inmediaciones del río Magdalena y unos sesenta individuos en total en el país. Los hipopótamos en Colombia son animales exóticos e introducidos, y con el tiempo fueron clasificados como especie invasora ya que su presencia representa riesgos ambientales al competir con especies nativas. Algunos de los efectos comprenden la alteración de hábitat, la perturbación de los procesos ecosistémicos y la desestabilización de los sistemas ambientales. Las medidas para su control que requieren la destinación de grandes presupuestos para la captura, control de natalidad, mantenimiento en cautiverio; o acciones socialmente cuestionables como la eutanasia, deberían ser establecidas de manera inmediata pues los recursos biológicos nativos, hidrobiológicos y pesqueros podrían verse afectados por culpa de esta especie invasora.

In 1985, Pablo Escobar brought to Colombia between two to six young hippos, during these 20 years they have mated and have been moving by the geographic area of Magdalena Medio. At present, it is believed that there could be between 10 to 30 free hippos near a large part of the Magdalena River, and a total population of about 60 in the country. Hippos in Colombia are an exotic and introduced specie that with time will become potentially invasive since they may represent environmental competition that puts native species in risk. The effects caused by the species are diverse, ranging from habitat alteration, to the disruption of ecosystem processes. Hippos in Colombia constitute a serious threat to native species and the stability of the affected environmental systems. The measures for its control should be established immediately (Destination of big budgets for capturing, birth control and maintenance in captivity or euthanasia) as the native aquatic and fishery biological resources could disappear over time.

Morphological Studies of Developmental Stages of Oculotrema hippopotami (Monogenea: Polystomatidae) Infecting the Eye of Hippopotamus amphibius (Mammalia: Hippopotamidae) Using SEM and EDXA with Notes on Histopathology.

The present study was performed to observe histopathological effects of Oculotrema hippopotami Stunkard, 1924 infection in the eye of Hippopotamus amphibius, as well as to reveal new details of morphology and structural features of this monogenean and its comparison between 2 age stages of the parasite. This was done using both light and scanning electron microscopy, energy dispersive X-ray analysis (EDXA) and histopathology. The presence of a mixture of different generations (adult and sub-adult) in one host individual is common for Oculotrema Stunkard, 1924 in contrast to Polystoma Zeder, 1800. New metrical and graphical information obtained for adults and sub-adults compared with the previous studies. Here we show the presence of genital papillae in adults, metrical data on the distal part of the vas deferens. SEM micrographs of sperm ejaculatory structures and information about the flattened dorsal side of the body provided for the first time. Histopathological changes, such as necrosis and hemorrhage in host tissues as a result of O. hippopotami attachment structures are described. Structural analysis of different body parts of O. hippopotami of both age groups are also included. We show qualitative differences in the presence of hardening ions (S, P, Ca) in attachment structures (oral and haptor suckers) that increase with the age of the worm. The presence of sub-adults and adults on the same host, together with high levels of infection without high pathogenicity may account for Oculotrema being one of the most successful parasites among the Monogenea.

Standardizing the evaluation of community-based conservation success.

Community-based conservation, which strives to simultaneously improve nature conservation and alleviate poverty, must provide biological and socioeconomic benefits that are linked through effective resilience mechanisms. To date, few community-based conservation initiatives have published comprehensive assessments that track performance in these elements of success. With 45% of the world's protected areas in comanagement with local communities, standardized measures to effectively evaluate the dual goals of community-based conservation are needed. We here introduce SPECCS, a user-friendly Standardized Protocol for Evaluating Community Conservation Success that incorporates an appraisal of data quality to responsibly assess progress over time or to compare effectiveness among different initiatives. We illustrate SPECCS's use by evaluating the Wechiau Community Hippo Sanctuary (WCHS) of northern Ghana 10 and 20 yr after its inception. The WCHS has the dual objective of protecting one of Ghana's few remaining hippopotamus populations while alleviating poverty in the surrounding communities through the creation of economic opportunity and infrastructure development. Results suggest stable project performance in the 10-yr (76%) and 20-yr (76%) evaluation, with an improvement in evaluation quality from 30% to 34%. The project is currently stronger in socioeconomic (performance 86%; quality 30%) than biological (60%; 32%) outcomes and in benefits (83%, 42%) than resilience (63%, 21%). Biological resilience is challenged by poor connectivity and limited project control over threats, whereas socioeconomic resilience is affected by a decision balance that continues to favor external stakeholders. SPECCS helps pinpoint strengths and weaknesses for timely adaptive management, strategic investments, and evidence-based recognition of community-based conservation successes.