Postnatal testis development in the collared peccary (Tayassu tajacu), with emphasis on spermatogonial stem cells markers and niche.

Collared peccaries (Tayassu tajacu) present a unique testis cytoarchitecture, where Leydig cells (LC) are mainly located in cords around the seminiferous tubules (ST) lobes. This peculiar arrangement is very useful to better investigate and understand the role of LC in spermatogonial stem cells (SSCs) biology and niche. Recent studies from our laboratory using adult peccaries have shown that the undifferentiated type A spermatogonia (Aund or SSCs) are preferentially located in ST regions adjacent to the intertubular compartment without LC. Following these studies, our aims were to investigate the collared peccary postnatal testis development, from birth to adulthood, with emphasis on the establishment of LC cytoarchitecture and the SSCs niche. Our findings demonstrated that the unique LC cytoarchitecture is already present in the neonate peccary's testis, indicating that this arrangement is established during fetal development. Based on the most advanced germ cell type present at each time period evaluated, puberty (the first sperm release in the ST lumen) in this species was reached at around one year of age, being preceded by high levels of estradiol and testosterone and the end of Sertoli cell proliferation. Almost all gonocytes and SSCs expressed Nanos1, Nanos2 and GFRA1. The analysis of SSCs preferential location indicated that the establishment of SSCs niche is coincident with the occurrence of puberty. Taken together, our findings reinforced and extended the importance of the collared peccary as an animal model to investigate testis function in mammals, particularly the aspects related to testis organogenesis and the SSCs biology and niche.

Organic matter loading by hippopotami causes subsidy overload resulting in downstream hypoxia and fish kills.

Organic matter and nutrient loading into aquatic ecosystems affects ecosystem structure and function and can result in eutrophication and hypoxia. Hypoxia is often attributed to anthropogenic pollution and is not common in unpolluted rivers. Here we show that organic matter loading from hippopotami causes the repeated occurrence of hypoxia in the Mara River, East Africa. We documented 49 high flow events over 3 years that caused dissolved oxygen decreases, including 13 events resulting in hypoxia, and 9 fish kills over 5 years. Evidence from experiments and modeling demonstrates a strong mechanistic link between the flushing of hippo pools and decreased dissolved oxygen in the river. This phenomenon may have been more widespread throughout Africa before hippopotamus populations were severely reduced. Frequent hypoxia may be a natural part of tropical river ecosystem function, particularly in rivers impacted by large wildlife.

Trophy Hunting and Sustainability: Temporal Dynamics in Trophy Quality and Harvesting Patterns of Wild Herbivores in a Tropical Semi-Arid Savanna Ecosystem.

The selective nature of trophy hunting may cause changes in desirable phenotypic traits in harvested species. A decline in trophy size of preferred species may reduce hunting destination competitiveness thus compromising the sustainability of trophy hunting as a conservation tool. We explored the trophy quality and trends in harvesting patterns (i.e., 2004-2015) of Cape buffalo (Syncerus caffer), African elephant (Loxodonta africana), greater kudu (Tragelaphus strepsiceros) and sable (Hippotragus niger) in Matetsi Safari Area, northwest Zimbabwe. We used long-term data on horn and tusk size, age, quota size allocation and offtake levels of selected species. To analyse the effect of year, area and age on the trophy size, quota size and offtake levels, we used linear mixed models. One sample t-test was used to compare observed trophy size with Safari Club International (SCI) minimum score. Trophy sizes for Cape buffalo and African elephant were below the SCI minimum score. Greater kudu trophy sizes were within the minimum score threshold whereas sable trophy sizes were above the SCI minimum score between 2004 and 2015. Age at harvest for Cape buffalo, kudu and sable increased whilst that of elephant remained constant between 2004 and 2015. Quota size allocated for buffalo and the corresponding offtake levels declined over time. Offtake levels of African elephant and Greater kudu declined whilst the quota size did not change between 2004 and 2015. The quota size for sable increased whilst the offtake levels fluctuated without changing for the period 2004-2015. The trophy size and harvesting patterns in these species pose a conservation and management dilemma on the sustainability of trophy hunting in this area. We recommend: (1) temporal and spatial rotational resting of hunting areas to create refuge to improve trophy quality and maintenance of genetic diversity, and (2) introduction of variable trophy fee pricing system based on trophy size.

Response of moose hunters to predation following wolf return in Sweden.

BACKGROUND: Predation and hunter harvest constitute the main mortality factors affecting the size and dynamics of many exploited populations. The re-colonization by wolves (Canis lupus) of the Scandinavian Peninsula may therefore substantially reduce hunter harvest of moose (Alces alces), the main prey of wolves. METHODOLOGY/PRINCIPAL FINDINGS: We examined possible effects of wolf presence on hunter harvest in areas where we had data before and after wolf establishment (n = 25), and in additional areas that had been continuously exposed to wolf predation during at least ten years (n = 43). There was a general reduction in the total number of moose harvested (n = 31,827) during the ten year study period in all areas irrespective of presence of wolves or not. However, the reduction in hunter harvest was stronger within wolf territories compared to control areas without wolves. The reduction in harvest was larger in small (500-800 km2) compared to large (1,200-1,800 km2) wolf territories. In areas with newly established wolf territories moose management appeared to be adaptive with regard to both managers (hunting quotas) and to hunters (actual harvest). In these areas an instant reduction in moose harvest over-compensated the estimated number of moose killed annually by wolves and the composition of the hunted animals changed towards a lower proportion of adult females. CONCLUSIONS/SIGNIFICANCE: We show that the re-colonization of wolves may result in an almost instant functional response by another large predator-humans-that reduced the potential for a direct numerical effect on the density of wolves' main prey, the moose. Because most of the worlds' habitat that will be available for future colonization by large predators are likely to be strongly influenced by humans, human behavioural responses may constitute a key trait that govern the impact of large predators on their prey.

A comparative assessment of the size of the frontal air sinus in the giraffe (Giraffa camelopardalis).

The current study examines the frontal air sinus of the giraffe (Giraffa camelopardalis) cranium with the aim of evaluating previously offered hypotheses as to why they have such an atypically voluminous frontal sinus relative to other artiodactyls. To date, no quantification of the frontal sinus in the adult or developing giraffe has been undertaken or compared to other artiodactyl species. Crania from eight species of adult artiodactyls, and giraffes varying in age from newborn to adult, were studied using CT scans to provide a volumetric assessment of the frontal sinus. Sinus volume was strongly correlated to cranial mass in the male giraffe ontogenetic series. The adult giraffe of both sexes were found to possess a far larger than predicted sinus volume relative to the relationship between frontal sinus volume and cranial mass observed in the other adult artiodactyls. Our results suggest that the volume of the frontal sinus in the giraffe is likely to be unique among artiodactyls, and the potential function and evolution we consider in light of several previously articulated hypotheses.

Physiological and life history strategies of a fossil large mammal in a resource-limited environment.

Because of their physiological and life history characteristics, mammals exploit adaptive zones unavailable to ectothermic reptiles. Yet, they perform best in energy-rich environments because their high and constant growth rates and their sustained levels of resting metabolism require continuous resource supply. In resource-limited ecosystems such as islands, therefore, reptiles frequently displace mammals because their slow and flexible growth rates and low metabolic rates permit them to operate effectively with low energy flow. An apparent contradiction of this general principle is the long-term persistence of certain fossil large mammals on energy-poor Mediterranean islands. The purpose of the present study is to uncover the developmental and physiological strategies that allowed fossil large mammals to cope with the low levels of resource supply that characterize insular ecosystems. Long-bone histology of Myotragus, a Plio-Pleistocene bovid from the Balearic Islands, reveals lamellar-zonal tissue throughout the cortex, a trait exclusive to ectothermic reptiles. The bone microstructure indicates that Myotragus grew unlike any other mammal but similar to crocodiles at slow and flexible rates, ceased growth periodically, and attained somatic maturity extremely late by approximately 12 years. This developmental pattern denotes that Myotragus, much like extant reptiles, synchronized its metabolic requirements with fluctuating resource levels. Our results suggest that developmental and physiological plasticity was crucial to the survival of this and, perhaps, other large mammals on resource-limited Mediterranean Islands, yet it eventually led to their extinction through a major predator, Homo sapiens.

Phylogeny, life history and the timing of molar crown formation in two archaic ungulates, Meniscotherium and Phenacodus (Mammalia, 'Condylarthra').

The condylarths, or archaic ungulates, are a paraphyletic mammalian group including a number of fossil taxa whose relationships are unresolved. Included are two genera from the Paleocene and Eocene of North America, Meniscotherium and Phenacodus. Some workers place both genera in the family Phenacodontidae, while others exclude the highly dentally derived Meniscotherium. In this study, we use growth increments in histological thin sections to examine the timing of crown formation in five molars of Meniscotherium and one each of Phenacodusintermedius and Phenacodus trilobatus. We also use perikymata counts on an additional six molars of Meniscotherium. Although estimated body mass and molar dimensions in Meniscotherium are smaller than in either species of Phenacodus, molar formation times are longer, ranging from 0.71 to 1.44 years. Both Phenacodus molars take less than a year to form. Crown extension rates, the rate at which the crown grows in height, are as low as 3-15 microm per day in Meniscotherium, but range from 13 to 54 microm per day in Phenacodus. Although striae periodicities and daily enamel secretion rate are similar in both genera, the differences in the crown extension rate and overall timing of crown formation suggest differences in life histories and raise questions about the phylogenetic relationship of the two genera.

Quantitative anatomy of the trachea of the giraffe (Giraffa camelopardalis rothschildi) / Anatomía cuantitativa de la tráquea de la jirafa (Giraffa camelopardalis rothschildi)

We described the macroscopic and quantitative anatomy of the trachea of the Giraffe (Giraffa camelopardalis rothschildi). The trachea of one juvenile male giraffe (25 months of age) weighing 754 kg was used in this study. The length of the neck was 125 cm. The trachea had 107 cm in length on its cervical part and 18 cm on its thoracic part. The total number of cartilage was 87.74 at the neck and 13 at the thorax. The general shape of the duct was mostly circular. The separation of the dorsal ends of the tracheal cartilages was pronounced in the first half of the cervical trachea, reducing caudally and overlapping in the thoracic trachea. In the caudal part the trachea had a tracheal bronchus for the cranial lobe of the right lung and the end of the trachea was divided into two main bronchi, where the left was larger in diameter.

Describimos la anatomía macroscópica y cuantitativa de la tráquea de la jirafa (Giraffa camelopardalis rothschildi). La tráquea de una jirafa macho joven (25 meses de edad), con un peso 754 kg fue utilizada en este estudio. La longitud del cuello era de 125 cm. La tráquea tuvo 107 cm de longitud en su parte cervical y 18 cm en su parte torácica. El número total de cartílagos fue de 87,74 en el cuello y 13 en el tórax. La forma general de la vía fue principalmente circular. La separación de los extremos dorsales de los cartílagos traqueales se pronunció en la primera mitad de la tráquea cervical, reduciéndose caudalmente y superponiéndose en la tráquea torácica. En la parte caudal la tráquea tenía un bronquio traqueal para el lobo craneal del pulmón derecho y el final de la tráquea se dividió en dos bronquios principales, donde el izquierdo fue de mayor diámetro.

A health evaluation in a colony of captive collared peccaries (Tayassu tajacu) in the Eastern Amazon.

This study pretends to determine baseline data on the health and mortality of a colony of captive collared peccaries in the Eastern Amazon (Belém, State of Pará, Brazil) during a 65-months survey. Thirty-nine out of 166 animals (23.5%) died and were examined post-mortem. Monthly mortality averaged 1.2%. The highest mortality rate was observed in newborns (74.4%). Abandonment by the mother and aggression were responsible for 24.1% and 13.8% of the total newborn deaths, respectively. Most frequent causes of non-neonatal death were food poisoning (50.0%) due to an episode of accidental bitter cassava leaves ingestion and traumatism due to aggressions between animals (10.0%). Results from serology for different infectious diseases showed that 4.9% (2/41) collared peccaries had antibodies against Brucella spp. and 9.8% (4/41) animals had antibodies to two different Leptospira spp. serovars, butembo and autumnalis. This is the first survey of morbidity and mortality in captive collared peccaries in the Amazon region.

Serial tranquilization of a reticulated giraffe (Giraffa camelopardalis reticulata) using xylazine.

A 5-yr-old captive-born reticulated giraffe (Giraffa camelopardalis reticulata) was tranquilized with i.m. xylazine 34 times in a 39-day period to allow nursing by her calf. Xylazine administered at approximately 0.16 mg/kg i.m. provided adequate sedation of the dam without detrimental side effects to the dam or the calf. While the dam was sedated, the calf was able to ingest adequate amounts of milk to produce acceptable weight gains until he was consistently eating solid foods.

Growth characteristics of the llama (Lama glama) from birth to 12 months old.

This study has characterised the growth patterns of the llama (Lama glama) from birth to 12 months old. Bodyweight growth was described as a function of age. As a means of predicting bodyweight, equations were developed which correlated bodyweight with specific body measurements. Regression analysis revealed a strong positive correlation of logtransformed measurements of thoracic circumference and height with bodyweight. Thoracic circumference (measured in cm) was a good predictor of bodyweight from the equation: bodyweight (kg) = (8.7 x 10(-4)) x circumference2.46 (r2 = 0.91).

Relationships between internal morphology and body mass in the developing, nursling collared peccary, Tayassu tajacu (Tayassuidae).

Morphological characteristics that reflect size differences due to dietary conditions are in wide use to assess nutritional status of many wild ungulates. This study was designed to provide baseline information on the development of internal visceral and endocrine structures of nursling collared peccaries (Tayassu tajacu) from birth to six weeks of age (weaning). A high energy-high protein ration was fed ad libitum to lactating females, and absolute and relative mass of selected visceral organ, endocrine, and fat depots were measured in various aged nurslings. Linear measurements were also obtained on components of the gastrointestinal tract. Allometric growth coefficients (b) varied considerably among the various organs and glands examined, ranging from below (brain, b = 0.26) to well above (thymus, b = 1.61) unity.

Age-related changes in the seminal vesicles of a Brazilian (Nelore) zebu.

Age changes in the structure of the seminal vesicles and in the rate of production of fructose and citric acid have been studied in a Brazilian (Nelore) zebu, from the fetal period to 36 months of age. At 3 and 6 months, the microscopic anatomy of the gland resembled that of the fetus; the tubules of the seminal vesicles had a reduced diameter and a low epithelial layer; only a few presented traces of secretion, and tissue contents of fructose and citric acid were accordingly low. At 12 months, the tubules were more ramified and had a larger diameter. In the 18-month-old animals the seminal vesicles presented substantial modifications; the tubules were large, with irregular lumina and surrounded by narrow stroma, the epithelial layer was higher than that of previous stages and its columnar cells had nuclei located basally. Tissue levels of fructose increased rapidly between 12 and 18 months. At 24 months, the seminal vesicles had reached the adult condition characterized by intense proliferation of tubules with irregular lumina and abundant secretory material. Numerous dark columnar cells were found in the epithelium. Seminal vesicles of Nelore zebus contain less fructose and citric acid than those of taurine bulls of comparable age.

The development of the reproductive organs of the male giraffe, Giraffa camelopardalis.

The reproductive organs of the male giraffe differ little in morphology and histology from those of other ungulates. There is some indication that gonadal hypertrophy occurs in late fetal life. Spermatogenesis begins at 3-4 years of age and coincides with a rapid increase of testicular weight and seminiferous tubule diameter. In the fetal testis the main hormone is androsteredione (2.73 microgram/g) but in adult testes testosterone is predominant (less than 10.08 microgram/g) and delta' testosterone may also be present.