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William L. Franklin - One of the best experts on this subject based on the ideXlab platform.
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The enigma of Guanacos in the Falkland Islands: the legacy of John Hamilton
Journal of Biogeography, 2005Co-Authors: William L. Franklin, Melissa M. GrigioneAbstract:Aim To address the biogeographical enigma of why Guanacos (Lama guanicoe) are in the Falkland Islands we investigated the following questions: (1) What was the origin of the introduced Guanacos? (2) What were the initial population sizes? (3) Why are they found only on one island? and (4) Who was John Hamilton and what role did he play? Location The Falkland Islands are located in the South Atlantic Ocean 600 km east of Patagonia at the southern end of South America. While dominated by East and West Falkland Islands, the archipelago is composed of some 750 islands. Sedge and Staats Islands, two small outlying islands of West Falkland, are the focus of this paper. Methods Historical information was collected from known relevant documents housed at the Falkland Islands Government Archives in Stanley, and personal interviews conducted with past and present residents of West Falklands. Research expeditions were made to Staats Island in 1999, 2002 and 2003 to assess the Guanaco population size, distribution and social structure. Results Guanacos were unsuccessfully introduced in 1862 to East Falkland south of Mt Pleasant where Prince Alfred hunted them in 1871. John Hamilton, Scottish immigrant to the Falklands and Patagonia of southern Argentina and Chile, was the driving force in the introduction of Guanacos from the region of Rio Gallegos, Argentina during the 1930s. The Guanaco was one of several wildlife species he introduced, however, only the Guanaco, Patagonia grey fox (Dusicyon griseus) and perhaps the sea otter (Lutra felina) survive. Hamilton's acting agent, Jimmy Miller, imported four shipments totalling 26 Guanacos from 1934 to 1939. In 1934 the Falkland Government authorized Miller to introduce Guanacos to Sedge Island, all 11 of which disappeared. Whether intentional or accidental, 15 Guanacos were taken to Staats Island, an islet of 500 ha on the western edge of the archipelago. Historically, Guanacos are unexpected on Staats Island because documentation authorizing their introduction is unknown. Guanaco numbers have fluctuated widely on Staats Island for 65 years primarily due to culling. In 1959 the population was dangerously close to extirpation, but today 400 thrive there. A severely reduced gene pool and genetic bottlenecking were suggested by recent field studies, revealing preliminary evidence of deleterious consequences of inbreeding. Main conclusions John Hamilton, spirited and visionary Scottish immigrant to the Falklands in the early 1880s, was responsible for the introduction of Guanacos into the Falkland Islands. While there are some gaps in the historical events, the enigma of how and why Guanacos were introduced to a single island in the South Atlantic Ocean is understood. Today, Staats Island, as a closed system, is a rare natural experiment in progress. It offers unique opportunities for addressing advanced questions in ungulate population, behavioural and genetic ecology. The population potentially also represents breeding stock for farming the Guanaco's highly valuable wool on other islands. Thus, among his many efforts to practice land stewardship and promote economic diversity through the introduction of Patagonian wildlife, a remaining legacy of John Hamilton to the Falkland Islands is unmistakably the Guanacos of Staats Island.
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Activity budget patterns in family-group and solitary territorial male Guanacos
Revista chilena de historia natural, 2004Co-Authors: Julie K. Young, William L. FranklinAbstract:Observamos patrones de comportamiento de Guanacos machos territoriales (Lama guanicoe) en el Parque Nacional Torres del Paine, Chile. Comparamos el presupuesto de actividad de machos solos y en grupos familiares (n = 23) en diferentes habitat. No encontramos diferencias en los presupuestos de actividad de machos basados en el tipo de grupo social, numero total de hembras o numero total de Guanacos presentes, o la edad de los machos territoriales. Guanacos macho en todas las categorias asignaron alrededor de 65 % de su actividad a forrajeo. Por otra parte, detectamos una influencia del tipo de habitat sobre el tiempo asignado a interacciones agresivas y miscelaneas (defecacion, vigilancia al observador, rasgunando); las interacciones agresivas y conductas miscelaneas fueron mas frecuentes en cimas de colinas de areas dominadas por el arbusto mata barrosa (Mulinum spinosum). Es probable que el comportamiento de los machos territoriales del Guanaco este relacionado a los recursos defendidos mas que a una habilidad para atraer hembras y aumentar el exito de apareamiento
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Spatial distribution of Guanaco mating sites in southern Chile: conservation implications
Biological Conservation, 2003Co-Authors: Michael S Bank, Ronald J Sarno, William L. FranklinAbstract:We investigated the distribution, habitat characteristics and conservation value of mating areas in a wild population of Guanacos in Torres del Paine National Park, Chile. Copulating Guanacos were observed directly during December–January 1994–1995, 1995–1996 and 1997–1998. The timing of the breeding season was homogeneous across years. Copulation sites occurred in vega (ephemeral wetland) habitats (48.6%) greater than expected based on their relative availability (12.6%). A multivariate habitat analysis revealed that habitat composition of breeding habitats differed significantly from non-breeding areas (P < 0.001). Availability of trees and shrubs (breeding=5.5%; non-breeding=35.6%; P < 0.001) and grassland (breeding=34.6%; non-breeding =9.5%; P < 0.001) contributed most to the variation in habitat types among areas. Relative occurrence of pumas was significantly lower in breeding areas (P=0.04). The spatial arrangement of mating sites was similar among years suggesting that adult female and male Guanacos exhibited site fidelity to breeding sites. Since vegas were important habitats for mating it is critical that natural resource managers consider the importance of these ephemeral wetland resources to ensure for proper reproduction and viability of local Guanaco populations. # 2002 Elsevier Science Ltd. All rights reserved.
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predation of Guanacos lama guanicoe by southernmost mountain lions puma concolor during a historically severe winter in torres del paine national park chile
Journal of Zoology, 2002Co-Authors: Michael S Bank, Ronald J Sarno, Nichole K Campbell, William L. FranklinAbstract:The effects of mountain lion Puma concolor predation on Guanaco Lama guanicoe mortality was investigated during the historically severe winter of 1995 in Torres del Paine National Park, Chile. The 45 Guanaco carcasses located represented 3% of the entire Guanaco population of which 74% were mountain lion kills, 13% died from malnutrition, 2% died from fence entanglement and 11% died from unknown causes. Depleted bone marrow fat was observed in 20% of all carcasses. The number of Guanaco deaths differed among sex and age classes, particularly in juveniles (< 1 year of age), which died more often than expected (P < 0.001). Fresh Guanaco carcasses (n= 19) killed by mountain lions were located in tree and shrub habitats 79% of the time and were significantly greater than expected values based on the relative availability of these habitats (P < 0.001). Observations of the spatial distribution of mountain lion kills and Guanaco mixed-sex groups were similar (P= 0.10), suggesting that mountain lions responded to winter migratory movements made by Guanacos. Overall, adult Guanacos experienced surprisingly lower levels of mortality (adult male = 1%, adult female = 2%) than expected, despite the severe winter conditions, while juveniles experienced higher levels of mortality (13%) than expected. In comparison to other years (1991–96), the severe winter of 1995 (i.e. this investigation) had the greatest total mortality for juveniles, although the proportion of deaths caused by mountain lion predation for juveniles was greatest during other winters.
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Population Density and Annual Variation in Birth Mass of Guanacos in Southern Chile
Journal of Mammalogy, 1999Co-Authors: Ronald J Sarno, William L. FranklinAbstract:We investigated the influence of population density and meteorological conditions on annual birth mass of Guanacos in Torres del Paine National Park, Chile, from 1987 to 1996. Between 1987 and 1990, density of Guanacos on the study area nearly tripled from 16 to 43 animals/km 2 . Mean birth mass was significantly different across years, and there was a strong negative correlation between mean yearly birth mass and population density. There was no correlation between mean yearly birth mass and mean temperature or total precipitation in either winter or spring during this period. Since 1990, density of Guanacos has decreased, which we suspect is the result of degraded range conditions, partly due to overgrazing. Population censuses from other sectors of the park and the adjacent sheep ranch revealed increasing numbers of Guanacos, and the movement of tagged animals out of the study area into surroundings with lower Guanaco density.
Ronald J Sarno - One of the best experts on this subject based on the ideXlab platform.
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Spatial distribution of Guanaco mating sites in southern Chile: conservation implications
Biological Conservation, 2003Co-Authors: Michael S Bank, Ronald J Sarno, William L. FranklinAbstract:We investigated the distribution, habitat characteristics and conservation value of mating areas in a wild population of Guanacos in Torres del Paine National Park, Chile. Copulating Guanacos were observed directly during December–January 1994–1995, 1995–1996 and 1997–1998. The timing of the breeding season was homogeneous across years. Copulation sites occurred in vega (ephemeral wetland) habitats (48.6%) greater than expected based on their relative availability (12.6%). A multivariate habitat analysis revealed that habitat composition of breeding habitats differed significantly from non-breeding areas (P < 0.001). Availability of trees and shrubs (breeding=5.5%; non-breeding=35.6%; P < 0.001) and grassland (breeding=34.6%; non-breeding =9.5%; P < 0.001) contributed most to the variation in habitat types among areas. Relative occurrence of pumas was significantly lower in breeding areas (P=0.04). The spatial arrangement of mating sites was similar among years suggesting that adult female and male Guanacos exhibited site fidelity to breeding sites. Since vegas were important habitats for mating it is critical that natural resource managers consider the importance of these ephemeral wetland resources to ensure for proper reproduction and viability of local Guanaco populations. # 2002 Elsevier Science Ltd. All rights reserved.
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predation of Guanacos lama guanicoe by southernmost mountain lions puma concolor during a historically severe winter in torres del paine national park chile
Journal of Zoology, 2002Co-Authors: Michael S Bank, Ronald J Sarno, Nichole K Campbell, William L. FranklinAbstract:The effects of mountain lion Puma concolor predation on Guanaco Lama guanicoe mortality was investigated during the historically severe winter of 1995 in Torres del Paine National Park, Chile. The 45 Guanaco carcasses located represented 3% of the entire Guanaco population of which 74% were mountain lion kills, 13% died from malnutrition, 2% died from fence entanglement and 11% died from unknown causes. Depleted bone marrow fat was observed in 20% of all carcasses. The number of Guanaco deaths differed among sex and age classes, particularly in juveniles (< 1 year of age), which died more often than expected (P < 0.001). Fresh Guanaco carcasses (n= 19) killed by mountain lions were located in tree and shrub habitats 79% of the time and were significantly greater than expected values based on the relative availability of these habitats (P < 0.001). Observations of the spatial distribution of mountain lion kills and Guanaco mixed-sex groups were similar (P= 0.10), suggesting that mountain lions responded to winter migratory movements made by Guanacos. Overall, adult Guanacos experienced surprisingly lower levels of mortality (adult male = 1%, adult female = 2%) than expected, despite the severe winter conditions, while juveniles experienced higher levels of mortality (13%) than expected. In comparison to other years (1991–96), the severe winter of 1995 (i.e. this investigation) had the greatest total mortality for juveniles, although the proportion of deaths caused by mountain lion predation for juveniles was greatest during other winters.
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Population Density and Annual Variation in Birth Mass of Guanacos in Southern Chile
Journal of Mammalogy, 1999Co-Authors: Ronald J Sarno, William L. FranklinAbstract:We investigated the influence of population density and meteorological conditions on annual birth mass of Guanacos in Torres del Paine National Park, Chile, from 1987 to 1996. Between 1987 and 1990, density of Guanacos on the study area nearly tripled from 16 to 43 animals/km 2 . Mean birth mass was significantly different across years, and there was a strong negative correlation between mean yearly birth mass and population density. There was no correlation between mean yearly birth mass and mean temperature or total precipitation in either winter or spring during this period. Since 1990, density of Guanacos has decreased, which we suspect is the result of degraded range conditions, partly due to overgrazing. Population censuses from other sectors of the park and the adjacent sheep ranch revealed increasing numbers of Guanacos, and the movement of tagged animals out of the study area into surroundings with lower Guanaco density.
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ecology of the patagonia puma felis concolor patagonica in southern chile
Biological Conservation, 1999Co-Authors: William L. Franklin, Warren E. Johnson, Ronald J Sarno, Agustin J IriarteAbstract:The ecology of the Patagonia puma was studied in Torres del Paine National Park, Chile. Thirteen pumas were captured from 1986 to 1989 and equipped with radio transmitters. During the winter of 1988 there was one puma per 17 km 2 in the 200 km 2 study area. Home ranges varied from 24 to 107 km 2 . Female home ranges overlapped with those of other males and females extensively, but male ranges overlapped each other for only short time periods. Seven adult pumas had home ranges extending outside the park boundaries and at least three preyed on sheep. Guanacos Lama guanicoe, especially young animals, were the puma’s most important prey item by biomass, but European hares Lepus capensis were preyed upon more than expected relative to available biomass. Of 731 Guanaco skulls collected from 1979 to 1988, 33% showed clear evidence of having been killed by pumas. Over the past decade puma numbers are believed to have increased in the park, perhaps in response to an increase in Guanaco numbers and continued protection. With decreased hunting pressure and harassment by horses and dogs, pumas have habituated to people and are being observed more often by park visitors. # 1999 Elsevier Science Ltd. All rights reserved.
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Juvenile Guanaco survival: management and conservation implications
Journal of Applied Ecology, 1999Co-Authors: Ronald J Sarno, Warren E. Johnson, Michael S Bank, William R. Clark, Walter S. Prexl, Michael J. Behl, William L. FranklinAbstract:Summary 1. The Chilean National Forestry and Park Service is striving to implement a Guanaco management programme of sustained-yield use. To achieve this, the rate, variation and causes of juvenile Guanaco mortality must be understood thoroughly. Therefore, we monitored the survival of 409 radio-collared juvenile Guanacos in Torres del Paine National Park, Chile, from 1991 to 1996. 2. The Kaplan–Meier product limit estimator of survival for staggered entry was calculated, and survival rates between juvenile males and females and among years were compared using the lifetest procedure in SAS. The Cox proportional hazards model was used to relate mortality rate to explanatory variables such as juvenile sex, birth weight, adult female aggression towards researchers during the capture and tagging of newborns, population density, and mean monthly winter snowfall. 3. Mean juvenile survival rate (Ŝ) was 0·38, but varied between 0·31 and 0·55. Survival rates between the sexes were not significantly different, although male survival was lower than that of females. Mortality rate was highest during the first 14 days after birth. Most deaths occurred between birth and 7 months of age. 4. The risk of mortality increased by almost 6% with every 1 cm increase in winter snowfall, whereas the risk of mortality decreased by almost 24% as adult female aggression increased towards researchers. 5. Current management objectives are aimed at the implementation of a rational harvest of Guanacos on the Chilean side of the island of Tierra del Fuego. Our results provide improved and updated estimates of juvenile Guanaco survival and will aid in the modelling of harvest rates of Guanacos in southern Chile. Future proposed harvests from wild populations in southern Chile need to consider the rate and variation of this critical life-history parameter.
Andrés J. Novaro - One of the best experts on this subject based on the ideXlab platform.
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Roads have no effect on Guanaco habitat selection at a Patagonian site with limited poaching
Global Ecology and Conservation, 2018Co-Authors: Natalia Schroeder, Alejandro González, Michael J. Wisdom, Ryan M. Nielson, Mary M. Rowland, Andrés J. NovaroAbstract:Abstract Roads affect flora and fauna across the world. Large mammals are particularly vulnerable to road effects because their large home ranges lead to a higher probability of contact with road networks. Disturbance associated with roads can alter the probability of habitat use by making suitable habitat near roads inaccessible or underused. Many studies and monitoring programs for large mammals such as Guanaco (Lama guanicoe) in South America, however, rely on counts made from roads to estimate population abundance and distribution. These counts implicitly assume that animal responses to roads are negligible, an assumption almost universally unstudied. We used density surface models with aerial survey data to evaluate the effects of unpaved roads on Guanaco habitat selection, at the scale of the species' home range, in a Patagonian site with limited poaching. Contrary to expectations and regardless of disturbance level associated with roads, Guanacos did not avoid roads at site (0.36 km2) or patch (2.4 km2) scales during any season. We posit two non-exclusive hypotheses to explain our results: (1) disturbance levels of roads are below thresholds of Guanaco response, and (2) Guanacos in our study area tolerated motorized vehicles due to limited harassment by poachers from roads. Our results, considered with opposite findings of strong road effects on Guanaco at a landscape and regional scales, highlight the need to assess whether road surveys lead to biased estimates of ungulate abundance and distribution under different environmental conditions, human activities and scales of interest. Where long-term monitoring of large mammal populations relies on road surveys, aerial or other non-road surveys could be strategically conducted to determine whether counts from roads provide reliable estimates.
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response of pumas puma concolor to migration of their primary prey in patagonia
PLOS ONE, 2017Co-Authors: Maria L Gelin, Andrés J. Novaro, Lyn C Branch, Daniel H Thornton, Matthew Gould, Anthony CaragiuloAbstract:Large-scale ungulate migrations result in changes in prey availability for top predators and, as a consequence, can alter predator behavior. Migration may include entire populations of prey species, but often prey populations exhibit partial migration with some individuals remaining resident and others migrating. Interactions of migratory prey and predators have been documented in North America and some other parts of the world, but are poorly studied in South America. We examined the response of pumas (Puma concolor) to seasonal migration of Guanacos (Lama guanicoe) in La Payunia Reserve in northern Patagonia Argentina, which is the site of the longest known ungulate migration in South America. More than 15,000 Guanacos migrate seasonally in this landscape, and some Guanacos also are resident year-round. We hypothesized that pumas would respond to the Guanaco migration by consuming more alternative prey rather than migrating with Guanacos because of the territoriality of pumas and availability of alternative prey throughout the year at this site. To determine whether pumas moved seasonally with the Guanacos, we conducted camera trapping in the summer and winter range of Guanacos across both seasons and estimated density of pumas with spatial mark–resight (SMR) models. Also, we analyzed puma scats to assess changes in prey consumption in response to Guanaco migration. Density estimates of pumas did not change significantly in the winter and summer range of Guanacos when Guanacos migrated to and from these areas, indicating that pumas do not follow the migration of Guanacos. Pumas also did not consume more alternative native prey or livestock when Guanaco availability was lower, but rather fed primarily on Guanacos and some alternative prey during all seasons. Alternative prey were most common in the diet during summer when Guanacos also were abundant on the summer range. The response of pumas to the migration of Guanacos differs from sites in the western North America where entire prey populations migrate and pumas migrate with their prey or switch to more abundant prey when their primary prey migrates.
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Effects of livestock on Guanaco Lama guanicoe density, movements and habitat selection in a forest–grassland mosaic in Tierra del Fuego, Chile
Oryx, 2014Co-Authors: Claudio A. Moraga, Martín Cristian Funes, J. Cristóbal Pizarro, Cristóbal Briceño, Andrés J. NovaroAbstract:AbstractLocally abundant ungulates often come into conflict with human activities. After a population collapse that reached its nadir in the 1970s, the Guanaco Lama guanicoe population in Tierra del Fuego, Chile, recovered and is now in conflict with sheep ranching and commercial logging. We studied the effects of livestock density and environmental factors on Guanaco abundance and spatial ecology, using seasonal counts and radio-telemetry in a private protected area (Karukinka) and neighbouring ranches in a forest–grassland mosaic in Tierra del Fuego. Guanaco density was highest in low-elevation areas with more grassland cover and little snow accumulation in winter. In low-elevation areas, Guanaco density decreased with increasing livestock density. Radio-tracked Guanacos exhibited a partial migration pattern: two individuals migrated seasonally, selecting grasslands and avoiding forests mainly in summer, whereas six sedentary individuals used habitats according to their availability. Migratory Guanacos spent the summer in Karukinka and winter on nearby ranches. High sheep densities and poor range condition on the ranches reduce key forage resources available to Guanacos and may promote use of forests by Guanacos, affecting forest regeneration and increasing conflict with logging. Current Guanaco harvest by loggers may fail to reduce the impact of Guanacos on logged-forest regeneration if Guanaco spatial ecology and sheep management are not considered. Our results provide insight into the interactions among Guanacos, forests and livestock ranching, and may be used to reduce conflicts and guide conservation in the Fuegian ecosystem.
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Demographic effects of live shearing on a Guanaco population
Small Ruminant Research, 2012Co-Authors: Andrés Rey, Andrés J. Novaro, Mercedes Sahores, M. Laura GuichónAbstract:a b s t r a c t Live shearing of wild Guanacos (Lama guanicoe) is promoted as an alternative to livestock production and a conservation tool in the Argentinean Patagonia. However, biological sustainability of Guanaco shearing has not been evaluated. We studied movements, population trends, survival, and yearling recruitment of Guanacos, comparing sections with and without roundups on a Patagonian sheep ranch. A total of 2900 Guanaco captures occurred in 10 roundups from 2003 to 2007. We estimated Guanaco density and yearling/adult ratios with line transect surveys. We evaluated if Guanacos left the section with roundups through direct observation of tagged Guanacos and radiotelemetry. We estimated survival rate of shorn Guanacos using 1334 capture–recapture histories. Guanaco population trends in sections with and without roundups were stable throughout a normal-rainfall period and declined during the drought that followed. Roundups were followed by temporary declines in density estimates probably associated with altered Guanaco behavior. Tagged Guanacos were rarely observed outside the section with roundups and none of the radiocollared Guanacos permanently left the section. We estimated a constant annual survival rate for shorn Guanacos (82% SE = 0.01) that was independent of sex and age. Yearling proportions declined in the section with roundups 2–3 months after summer roundups. Our results suggest that, under conditions similar to those of our study (i.e. following animal welfare practices in a ranch with moderate livestock densities and sections without livestock), live shearing would not imperil wild Guanacos if roundups were conducted in spring and during normal-rainfall periods.
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Cooperative vigilance: the Guanaco's (Lama guanicoe) key antipredator mechanism.
Behavioural processes, 2012Co-Authors: Paula Taraborelli, Pablo Gregorio, Andrés J. Novaro, Pablo Gastón Moreno, Pablo Daniel CarmanchahiAbstract:The concept of sociality has been associated with the effectiveness of antipredator mechanisms, like cooperative vigilance and the dilution effect. Lama guanicoe (Guanaco) is a social native herbivore in South America and a social species. The objectives of this study were to evaluate the antipredator responses of different-sized groups of Guanacos in areas with varying predation risks and to determine antipredator mechanisms in Guanacos. For this, we measured different antipredator responses to a potential predator (human subjects). Detection of predator and flight distances from predator both increased with a greater number of Guanacos per group and with greater distances among Guanacos within the social group. Both buffer distance and flight time decreased with a greater number of Guanacos per group, but increased with greater distances among Guanacos inside the social group. Solitary adult males moved shorter distance and mixed groups moved greater distances. Flight distances were greater in areas with tall and dense vegetation than in areas with low vegetation. Buffer distance and flight time were shorter in undulating land than on flat lands, and groups were usually observed on hill slopes. Our results suggest that the benefit of social grouping in Guanacos is the increased probability of avoiding predator with cooperative vigilance and not with the dilution effect. This means that a predator could be detected earlier when approaching a Guanaco group than when approaching a solitary individuals and could thus be avoided.
J.a. Skidmore - One of the best experts on this subject based on the ideXlab platform.
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Assisted reproductive techniques for hybridization of camelids
Reproduction Fertility and Development, 2001Co-Authors: J.a. Skidmore, M. Billah, Roger V. Short, William R. AllenAbstract:The camelid family comprises the Old World camelids (or dromedary and Bactrian camels) and the New World camelids (namely the llamas, alpacas, Guanacos and vicunas). Although the species within each group can hybridize among themselves to produce fertile offspring, it is only recently that a hybrid between New and Old World camelids has been reported. To create this hybrid, semen was collected from male camels by artificial vagina (AV) and inseminated into female Guanacos (n= 9) and llamas (n= 3) at the appropriate stage of their follicular wave cycle. Similarly, Guanaco and llama semen was collected, also by AV, and inseminated into female camels (n= 42). Although several conceptions occurred, only one hybrid (camel sire×Guanaco dam) continued to term and was born alive after 328 days of gestation, and another is pregnant at the time of writing (camel sire×llama dam). Further studies are presently being carried out using extraspecific embryo transfer to try and improve the success rate of live offspring being born. Female Guanacos (n= 4) are treated with hormones to stimulate their ovaries to produce several follicles before being inseminated with camel semen. Of the 12 camel recipients that have to date received hybrid embryos (camel sire×Guanaco dam), 10 conceived, but 9 of these subsequently aborted between 30 and 365 days and only one recipient was still pregnant at the time of writing.
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Using modern reproductive methods to hybridize old and new world Camelids : Camelus dromedarius x Lama guanicoe
Revue d’élevage et de médecine vétérinaire des pays tropicaux, 2000Co-Authors: J.a. Skidmore, M. Billah, W. R. Allen, R. V. ShortAbstract:Un groupe de neuf femelles et un mâle Guanacos a ete maintenu au sein d'un important troupeau de dromadaires au Centre de reproduction camelin a Dubai. Les ovaires des femelles Guanacos et dromadaires etaient scannes regulierement et, quand ils presentaient un follicule dominant de 0,7-0,9 cm de diametre chez le Guanaco ou de 1,3-1,8 cm chez le dromadaire, les femelles recevaient une injection unique de GnRH analogue, buserelin (Receptal ; dromadaires : 20 μg i.v.; Guanacos: 10 μg i.v.) pour induire l'ovulation et subir une insemination 24 h apres. Trente femelles dromadaires ont ete inseminees a 50 occasions avec 2-4 ml de semence de Guanaco diluee a 1:1 avec du tampon vert (150-400 x 10 6 spermatozoides motiles), resultant en deux gestations; l'une a donne un produit mort-ne au 365 e jour de gestation et l'autre s'est terminee par un avortement au 260 e jour. De la meme maniere, neuf femelles Guanacos ont ete inseminees a 34 occasions avec de la semence diluee de dromadaire (300-400 x 10 6 spermatozoides motiles), donnant lieu a six conceptions; deux ont disparu par resorption entre 25-40 jours apres l'ovulation, deux ont abouti a des avortements respectivement aux 291 e et 302 e jours, une autre s'est terminee par un produit mort-ne au 365 e jour et la derniere a produit un mâle hybride ne vivant au 328 e jour. A la connaissance des auteurs, c'est le premier hybride viable de camelides du Nouveau et de l'Ancien Monde. Son existence souligne un remarquable degre de conservation des processus de reproduction entre ces deux especes.
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Hybridizing Old and New World camelids: Camelus dromedarius x Lama guanicoe.
Proceedings. Biological sciences, 1999Co-Authors: J.a. Skidmore, M. Billah, Roger V. Short, M. Binns, W. R. AllenAbstract:Thirty female dromedary camels were inseminated on a total of 50 occasions with 2 to 4 ml of fresh Guanaco semen diluted with an equal volume of commercially available camel semen extender. Similarly, nine female Guanacos were inseminated on 34 occasions with 4–6 ml of fresh, diluted camel semen. Only two of the dromedary females conceived; one aborted a female foetus on day 260 of gestation and the other gave birth to a stillborn female calf on day 365. Six conceptions occurred in the female Guanacos. Two of these conceptuses, diagnosed by ultrasound, were resorbed between days 25 and 40 of gestation, one female foetus was aborted on day 291, another female foetus was aborted on day 302, and one female calf was stillborn on day 365 of gestation. The sixth foetus, a male, was born prematurely but alive after a 328–day gestation. It had a phenotypic appearance intermediate between that of a camel and a Guanaco and its hybrid parentage was confirmed by the DNA fingerprinting of eight llama microsatellites. To our knowledge, this is the first viable hybrid ever to be produced between Old World and New World camelids, which have been reproductively isolated from one another for at least 11 million years. The preponderance of female hybrids is in accordance with Haldane9s law. Histological examination of their ovaries revealed a failure of meiosis, with only an occasional abnormal oocyte surrounded by follicle cells. Although the diploid chromosone number of camels and Guanacos is the same (2 n =74), sufficient genetic change has taken place to make the pairing of homologous chromosomes no longer possible.
Alex Fajardo - One of the best experts on this subject based on the ideXlab platform.
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Browsing by Guanaco (Lama guanicoe) on Nothofagus pumilio forest gaps in Tierra del Fuego, Chile
Forest Ecology and Management, 2004Co-Authors: Lohengrin A. Cavieres, Alex FajardoAbstract:The presence of Guanaco (Lama guanicoe, Muller 1776, Camelidae) in forests of Nothofagus pumilio (Poepp. et Endl.) Krasser. (lenga) in Tierra del Fuego has been associated with browsing damage in the regeneration of these forests, but little quantitative data are available. In developing and implementing forest management plans for N. pumilio forests, the effects of Guanaco browsing are a major source of variation in attaining regeneration and growth goals, however, Guanaco is not generally accounted for in management planning in the region. In this study we examined the browsing damage levels of Guanaco and introduced livestock on N. pumilio regeneration occurring in canopy gaps of forests in Tierra del Fuego, Chile (54812 0 S, 68845 0 W). Relationships were established between browsing levels and gap characteristics like gap size, gap age and abundance of regeneration. Results indicated that 88.7% of regeneration growing in gaps experienced some degree of damage by browsing, and that the degree of damage was higher in smaller gaps, which might depend on the size of Guanaco herds. We also found that the degree of damage was positively related with the abundance of Guanacos. However, no relationship was found between gap size and abundance of Guanacos. # 2004 Elsevier B.V. All rights reserved.
