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Proefschrift Maastricht. / Lit.opg. - Met samenvatting in het Nederlands.

One of the most diverse groups of parasitic nematodes includes the nematodes of the suborder Trichostrongylina. Trichostrongyle systematic classification is based on the study of the anterior end, the female reproductive system, the male copulatory bursa and cuticular ridges, which make up the synlophe. These morphological characters also assist taxonomists to characterize species and assign them into one of the three superfamilies. Heligmosomoidea is the most diverse superfamily, including Viannaiidae. This family represents one of the major evolutionary radiations of trichostrongyles in South America. Members of Viannaiidae parasitize a variety of mammals endemic to the Neotropics including, but not limited to, the opossums. Viannaiids have great morphological variation in the reproductive organs of the females and the secondary sexual structures of the males (e.g., rays in the bursa). Consequently, the placement of these species in classification schemes has drastically changed over time. The prevailing taxonomy relies on the host used by the parasites as well as their geographic distribution. Viannaiidae has always included monodelphic nematodes with simple synlophes, yet it eventually included species in the genus Travassostrongylus, which the morphology is very distinct from the rest of the members of the family. Differences pertain to a greater number of ridges of the synlophe and the didelphic female reproductive system. These features are more similar to trichostrongyles in Herpetostrongylidae and Nicollinidae, which infect Australian vertebrates, the majority of which are marsupials. I herein document the diversity of this group by reporting the presence of a putative new species and use five gene regions to reconstruct the phylogeny of Viannaiidae exclusive of didelphid marsupials. I used the resulting phylogeny to test the monophyly of Travassostrongylus and Viannaia and to reconstruct the character evolution of the monodelphic/didelphic condition and the ornamentation of the cuticle. The phylogeny indicates that Viannaiidae is not monophyletic, recovering a clade with the Travassostrongylus species and trichostrongyles from Australian fauna. The tests for character reconstruction assist in determining that the didelphic condition and the presence of dorsal synlophe ridges in Travassostrongylus and Austrostrongylus may be traits inherited from a common ancestor. Furthermore, it was apparent that a character change from didelphic to monodelphic occurred in the common ancestor of the Viannaia species. This ancestor also underwent a change from a dorsal cuticle with ridges to a smooth cuticle. Though the study suggests that Viannaiidae is not monophyletic, the inclusion of more species from these genera and the viannaiids found in hystricognaths from the New World rodents will conclusively determine the affinities of the members of the family. Finally, I suggest that the relationship between the species in Travassostrongylus and the Australian parasites dates to the Gondwana landmass and that these trichostrongyles, or their ancestors, were present in the marsupials of that time period. The examination of microbiotheriids could provide more information and illuminate the factors that led to the evolutionary relationship between the parasites of America and Australia.

Eighty-three Didelphis virginiana from the Portland metropolitan area were collected and studied from December 1974 through May 1976. Males averaged 3394 g, females 2318 g. An annual sex ratio of 68.7:31.3 was recorded. Data indicate the possibility of a year-round breeding season and suggest the occurrence of three peaks of reproductive activity: January-February, April-May and October-November. The six primary foods consumed annually are: leaf litter, mammals, gastropods, earthworms, grasses and pet food. Seasonal composition and diversity in the diet is marked. Five new parasite-host records were established. These include mites: Androlaelaps fahrenholsi, Haemogamasus nidi, Eulaelape stabularis tick, Ixodes angustus, and a nematode, Toxocara canis. Both minimum and maximum temperature, and perhaps precipitation to a lesser degree, affect the activity of the species. Nest building by an immature opossum is described.

Se estudió la dieta de cuatro especies de marsupiales didélfidos, Philander andersoni, P. opossum, Metachirus nudicaudatus y Didelphis marsupialis en los bosques húmedos de los alrededores de la carretera Iquitos-Nauta, Loreto, Perú, mediante el análisis de sus contenidos estomacales. El análisis de los datos incluyó comparaciones intraespecíficas a nivel de edad y sexo, y comparaciones interespecíficas a nivel de época y hábitats; mediante análisis de varianza, los índices de amplitud y sobreposición de nicho. El consumo de insectos fue predominante en M. nudicaudatus, comprendiendo más del 60% del volumen de la dieta. Las diferencias significativas se encontraron a nivel intraespecífico según edad en M. nudicaudatus en el consumo de plantas, y a nivel interespecífico se observó que P. opossum consume Chilopoda y M. nudicaudatus consume Insecta a diferencia de las otras especies estudiadas, y no se encontró variación por época ni por hábitat. La mayor amplitud de nicho ocurrió en D. marsupialis (5.53) y la menor en M. nudicaudatus (2.1). Mientras que la sobreposición de nichos fue más alta entre las especies de P. andersoni y M. nudicaudatus (0.99). Las especies de marsupiales muestran algunas variaciones intraespecíficas e interespecíficas en sus hábitos alimenticios y por lo general usan los recursos similares disponibles, alimentándose de un alto porcentaje de Insecta, seguido de las categorías plantas y Vertebrata. Los resultados muestran algunas semejanzas con otros estudios realizado en el Neotrópico y constituyen el primer aporte a la historia natural de estas especies en Perú. / -- The natural diet of four didelphids marsupial species was studied; Philander andersoni, P. opossum, Metachirus nudicaudatus and Didephis marsupialis in the rainforest surrounding of the Iquitos-Nauta road, Loreto, Peru, through stomach contents analysis, The data analysis included intraespecific relationships (age and sex), and interspecific relationships (climatic season and habitat) comparisons, through variance analysis, niche breadth and overlap indices. The insect consumption was higher in M. nudicaudatus, showing more than 60% of the total diet volume. The statistically significant differences were found at the intraspecific relationship level according to the age in the plant consumption in M. nudicaudatus, and interspecific relationships differences were found for P. opossum which eats Chilopoda and M. nudicaudatus eats Insecta with respect the other species studied here. Variation in climatic season and habitat were not found in the studied species. D. marsupialis presented the largest niche breadth (5.53) and M. nudicaudatus the lowest (2.1). Meanwhile, the highest niche overlap occurred between P. andersoni and M. nudicaudatus (0.99). The species showed some intraspecific and interspecific variations in food habits, and generally use the same available resources, feeding at a high percentage of the Insecta category, followed by plants and Vertebrata categories. The results show similarities with another studies developed in the Neotropic and constitute the first contribution to the natural history of those species in Peru. / Tesis

Behavior and communication modes were studied in captive <u>Monodelphis domestica</u>, a small solitary, nocturnal, omnivorous marsupial in the family Didelphidae. The social biology was examined to evaluate the importance of visual, olfactory, auditory, and tactile communication. Social contexts were compared in 124 encounters of 30 min each. An ethogram was developed containing 74 behaviors which sorted into 9 major behavioral categories: grooming and resting, exploration, attention, scent marking, vocalizations, social contact, aggression, retreat, and sexual. Solitary <u>Monodelphis</u> explored, groomed, and scent marked. Familiar male-female pairs displayed less aggression than unfamiliar male-female pairs. Non-estrous females aggressively repelled males and exhibited much dominance related behavior, but male-male pairs were the most agonistic. Seven scent marking modes were identified which functioned to communicate individual identity and sexual advertisement. Males could distinguish sex and estrous condition of conspecific urine donors by olfaction. Dig perineal dragging, lateral side rubbing, and hip rubbing were unique to <u>Monodelphis</u>. Tongue protrusion was observed and may be related to vomeronasal organ function. Four principal agonistic vocalizations were used while one, clicking, was observed only in male sexual behavior and submissive contexts by both sexes. A chittering vocalization is described. Social contact behaviors included approaches and directed sniffs. Males sniffed female cloacal regions who in turn sniffed the ma1es’ sides and abdomens. Dominance-subordinance relationships were characterized. Behavior of close relatives <u>Didelphis</u> and <u>Marmosa</u> was similar, but some behaviors were unique to <u>Monodelphis</u>. / Master of Science / incomplete_metadata

Thylamys Gray 1843 (Didelphimorphia: Marmosidae) es un género que incluye pequeñas marmosas con características morfológicas distintivas, distribuidas mayormente en hábitats abiertos, secos, y semiáridos del sur de Sud América. Al igual que otros géneros de pequeños mamíferos, su diversidad y distribución estan pobremente documentadas. El nombre Thylamys fue empleado inicialmente como un subgénero de Marmosa, teniendo una composición variable, pero luego fue restringido a un grupo natural. La situación de la mayoría de los taxa asociados al género permanece oscurecida debido a que no existen series adecuadas para ellas. Sólo una especie se reconoce como presente en el Perú: Thylamys elegans (sensu Gardner, 1993). Sin embargo, hasta cinco nombres específicos se han usado para referirse a estas poblaciones, y la variación es evidente en el material disponible. Mediante el estudio detallado de la variación morfológica y morfométrica de estas poblaciones, así como de aquellas correspondientes a T. elegans de Chile, y a otros taxa de Bolivia, Argentina, Paraguay y Brasil, se analiza la diversidad y distribución del género en el Perú y en parte de Sudamérica. La comparación del material de Thylamys de Perú con ejemplares representativos de otros taxa, permite reconocer siete especies: T. elegans, T. pallidior, T. venustus, T. tatei, T. macrurus, T. pusillus y T. velutinus. Sólo dos de ellas: T. pallidior y T. tatei, se encuentran en Perú. Ambas muestran características diferenciales de T. elegans. La distribución de T. elegans se restringe al centro de Chile, mientras T. tatei se halla sólo en la costa norte de Perú. Al contrario, T. pallidior se extiende latitudinalmente desde el norte de Perú hasta la Patagonia en el sur de Argentina. Basado en las características morfológicas evaluadas, las especies se agrupan en unidades geográficas que podrían corresponder a grupos naturales. Se propone una hipótesis biogeográfica para explicar la colonización de la vertiente occidental por este género, propio de ambientes áridos, bajos, y templados al este de los Andes. El origen de estas poblaciones sería a través de dispersiones “pasivas” por elevación de los Andes, y luego por colonización de hábitats áridos durante las fluctuaciones climáticas del Plioceno-Pleistoceno. Mayores estudios para determinar sus afinidades son necesarias para entender estos procesos, sólo entonces será posible llevar a cabo planes exitosos para su conservación. / The genus Thylamys Gray 1843 (Didelphimorphia: Marmosidae) includes small mouse opossums with distinctive morphological traits, mainly distributed on dry and open habitats of southern South America. Similar to other Neotropical small mammals, its species diversity and distribution are poorly known. The name Thylamys was early used as a subgenus of Marmosa, with an unstable definition, but then it was restricted to a natural group. However, the status for most of the taxa remains obscured because there are no enough series to study them. Only one species is recognized as present in Peru: Thylamys elegans (sensu Gardner, 1993). However, as much as five specific names have been used to refer to these populations, and the variation is evident in the available material. Through a detailed survey of the morphological and morphometric variation withing and among these populations, as well as those from T. elegans of Chile, and other taxa from Bolivia, Argentina, Paraguay, and Brazil, I analyze the diversity and distribution of the genus in Peru and part of South America. Comparison of Peruvian material of Thylamys with representative specimens of other taxa, allowed to recognize seven species: T. elegans, T. pallidior, T. venustus, T. tatei, T. macrurus, T. pusillus, and T. velutinus. Only two species, T. pallidior and T. tatei, are found in Peru. Both show distinctive characteristics in regard to the type species, T. elegans. The distribution of T. elegans is restricted to central Chile, and T. tatei is only found in the north coastal of Peru. On the other hand, T. pallidior ranges over a considerable latitudinal extension, from north Peru to the Patagonia of southern Argentina. According to the evaluation of morphological characters, the species are grouped in geographic units, which could equal to natural groups. I propose a biogeographic hypothesis to explain the colonization of the western slope by the genus, typically found at low, dry, and temperate areas to the east of the Andes. The origen of these populations would be through “passive” dispersal during uplift of the Andes, and then by colonization of dry habitats during the climatic fluctuations of the Plio-Pleistocene. Further studies are necessary to assess their relationships and to understand the underlying processes. Only then, it will be posible to carry out succesful plans for its conservation.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Some animals present natural resistance to the effects of snake venoms that can be explained by the presence of neutralizing factors in their blood serum. The resistance of South American Didelphis marsupialis, against crotalid venoms, especially of the genus Bothrops, of utmost medical importance in Brazil, has been object of investigation in the last few years. Bothrops erythromelas, known as âjararaca-da-secaâ or âjararaca-malha-de-cascavelâ is responsible for a great deal of snakebites in Northeastern Brazil. The venom of this snake induces acute renal failure (Wen et al., 1989). In this work, we examined the action of the antibothropic factor isolated from Didelphis marsupialis on the renal effects of B. erythromelas venom in the absence of systemic interactions. Isolated kidneys from Wistar rats, weighing 260 to 300g, were perfused with Krebs-Henseleit solution containing 6g% of bovine serum albumin, Bothrops erythromelas venom (10mg/mL), antibothropic factor from Didelphis marsupialis (10mg/mL), antibothropic factor from Didelphis marsupialis (10mg/mL) incubated with Bothrops erythromelas venom (10mg/mL) and antibothropic factor from Didelphis marsupialis (30mg/mL) incubated with Bothrops erythromelas venom (10mg/mL). The parameters studied included perfusion pressure (PP), renal vascular resistance (RVR), glomerular filtration rate (GFR), urinary flow (UF), percent sodium, potassium and chloride tubular transport (%TNa+, %TK+ and %TCl-), and osmotic clearance (Cosm). The control group perfused with albumin was functionally stable for over 120 min. The administration of antibothropic factor from Didephis marsupialis (10Âg/mL) did not modify the functional kidney parameters when compared with control group. The infusion of B. erythromelas venom (10Âg/mL) caused a significant decrease (p< 0,05*) in perfusion pressure and renal vascular resistance at 60, 90 and 120 min. with maximum effect at 90 min. (PP&#8594; ct90 = 108.70 Â 5.1 mmHg vs vBE90 = 65.20 Â 5.6* mmHg) and (RVR&#8594; ct90 = 5.76 Â 0.65 mmHg/mL.g-1.min-1. vs vBE90 = 3.10 Â 0.45* mmHg/mL.g-1.min-1). The glomerular filtration rate decreased at 60 min. and increased at 90 and 120 min (ct120 = 0.72 Â 0.10 mL.g-1.min-1. vs vBE120 = 1.24 Â 0.26* mL.g-1.min-1). After administration of the venom, the urinary flow increased at 90 and 120 min when compared with control group (ct120 = 0.14 Â 0.07 mL.g-1.min-1. vs vBE120 = 0.47 Â 0.08* mL.g-1.min-1). Sodium transport percent decreased at 90 and 120 min. (ct90 = 79.18 Â 0.88% vs vBE90 = 58.35 Â 4.86* %). Potassium transport percent decreased at 90 and 120 min. (ct90 = 67.20 Â4.04% vs vBE90 = 57.32 Â 5.28* %). Chloride transport percent decreased at 60, 90 and 120 min. (ct90 = 77.32 Â 2.22% vs vBE90 = 55.97 Â 5.52* %). The osmotic clearance increased at 90 and 120 min. (ct120 = 0.13 Â 0.01 mL. g-1.min-1 vs vBE120 = 0.42 Â 0.07* mL.g-1.min-1). The antibothropic factor from Didelphis marsupialis (10Âg/mL) incubated with B. erythromelas venom (10Âg/mL) blocked only the effects promoted by venom in the perfusion pressure and in the renal vascular resistance, whereas the highest concentration of the antibothropic factor from Didelphis marsupialis (30Âg/mL) reversed the effects on renal vascular resistance, urinary flow, glomerular filtration rate, percent sodium potassium and chloride tubular transport (%TNa+, %TK+ and %TCl-), and osmotic clearance (Cosm). In conclusion, B. erythromelas venom altered all the renal functional parameters evaluated and the antibothropic factor from D.marsupialis was able to inhibit the effects induced by the venom in rat isolated kidney. / Some animals present natural resistance to the effects of snake venoms that can be explained by the presence of neutralizing factors in their blood serum. The resistance of South American Didelphis marsupialis, against crotalid venoms, especially of the genus Bothrops, of utmost medical importance in Brazil, has been object of investigation in the last few years. Bothrops erythromelas, known as âjararaca-da-secaâ or âjararaca-malha-de-cascavelâ is responsible for a great deal of snakebites in Northeastern Brazil. The venom of this snake induces acute renal failure (Wen et al., 1989). In this work, we examined the action of the antibothropic factor isolated from Didelphis marsupialis on the renal effects of B. erythromelas venom in the absence of systemic interactions. Isolated kidneys from Wistar rats, weighing 260 to 300g, were perfused with Krebs-Henseleit solution containing 6g% of bovine serum albumin, Bothrops erythromelas venom (10mg/mL), antibothropic factor from Didelphis marsupialis (10mg/mL), antibothropic factor from Didelphis marsupialis (10mg/mL) incubated with Bothrops erythromelas venom (10mg/mL) and antibothropic factor from Didelphis marsupialis (30mg/mL) incubated with Bothrops erythromelas venom (10mg/mL). The parameters studied included perfusion pressure (PP), renal vascular resistance (RVR), glomerular filtration rate (GFR), urinary flow (UF), percent sodium, potassium and chloride tubular transport (%TNa+, %TK+ and %TCl-), and osmotic clearance (Cosm). The control group perfused with albumin was functionally stable for over 120 min. The administration of antibothropic factor from Didephis marsupialis (10Âg/mL) did not modify the functional kidney parameters when compared with control group. The infusion of B. erythromelas venom (10Âg/mL) caused a significant decrease (p< 0,05*) in perfusion pressure and renal vascular resistance at 60, 90 and 120 min. with maximum effect at 90 min. (PP&#8594; ct90 = 108.70 Â 5.1 mmHg vs vBE90 = 65.20 Â 5.6* mmHg) and (RVR&#8594; ct90 = 5.76 Â 0.65 mmHg/mL.g-1.min-1. vs vBE90 = 3.10 Â 0.45* mmHg/mL.g-1.min-1). The glomerular filtration rate decreased at 60 min. and increased at 90 and 120 min (ct120 = 0.72 Â 0.10 mL.g-1.min-1. vs vBE120 = 1.24 Â 0.26* mL.g-1.min-1). After administration of the venom, the urinary flow increased at 90 and 120 min when compared with control group (ct120 = 0.14 Â 0.07 mL.g-1.min-1. vs vBE120 = 0.47 Â 0.08* mL.g-1.min-1). Sodium transport percent decreased at 90 and 120 min. (ct90 = 79.18 Â 0.88% vs vBE90 = 58.35 Â 4.86* %). Potassium transport percent decreased at 90 and 120 min. (ct90 = 67.20 Â 4.04% vs vBE90 = 57.32 Â 5.28* %). Chloride transport percent decreased at 60, 90 and 120 min. (ct90 = 77.32 Â 2.22% vs vBE90 = 55.97 Â 5.52* %). The osmotic clearance increased at 90 and 120 min. (ct120 = 0.13 Â 0.01 mL. g-1.min-1 vs vBE120 = 0.42 Â 0.07* mL.g-1.min-1). The antibothropic factor from Didelphis marsupialis (10Âg/mL) incubated with B. erythromelas venom (10Âg/mL) blocked only the effects promoted by venom in the perfusion pressure and in the renal vascular resistance, whereas the highest concentration of the antibothropic factor from Didelphis marsupialis (30Âg/mL) reversed the effects on renal vascular resistance, urinary flow, glomerular filtration rate, percent sodium potassium and chloride tubular transport (%TNa+, %TK+ and %TCl-), and osmotic clearance (Cosm). In conclusion, B. erythromelas venom altered all the renal functional parameters evaluated and the antibothropic factor from D.marsupialis was able to inhibit the effects induced by the venom in rat isolated kidney