Organisation sociale, dynamique de population, et conservation du cerf huemul (Hippocamelus bisulcus) dans la Patagonie du Chili

Résumé : Ce projet de recherche a examiné l'organisation sociale, le cycle biologique et la dynamique des populations de cerf huemul (Hippocamelus bisculus) par l'utilisation de techniques aussi bien moléculaires que de suivi des individus, et fournit des informations utiles pour la conservation de cette espèce en danger. La population de la Reserve Nationale Lago Cochrane, en Patagonie chilienne, a été suivie entre mars 2005 et juin 2008. Pour reconnaitre et suivre les individus (n = 55), les cerfs ont été équipés de colliers émetteurs, d'étiquettes auriculaires émettrices, et d'étiquettes auriculaires conventionnelles. L'organisation sociale du huemul a été analysée par un index d'association (le "ratio simple"), pour établir les tendances d'associations spatiales et temporelles des individus identifiables de chaque sexe. Le huemul forme de petits groupes (moyennes ± ES: 1.68 ± 0.25 individus) mixtes, durant l'année. J'ai attribué cette association inhabituelle à leur faible dimorphisme sexuel en terme de taille, ce qui engendre des besoins nutritionnels et des budgets d'activité similaires pour les deux sexes. Les femelles adultes peuvent s'associer en fonction des relations de parenté. Les deux sexes sont nettement phylopatriques et non-migratoires. Les maux adultes s'évitent, et peuvent bénéficier de l'association avec des femelles ce qui diminue leur propre risque de prédation. Les maux adultes qui défendaient des territoires ont produit plus de faons que les maux non territoriaux. Les simulations du taux de croissance fini (A,) de cette population suggèrent qu'elle est soit stable soit en déclin. L'analyse d'élasticité a montré que les changements en terme de survie des femelles adultes auraient des effets sévères sur X. Bien que la survie des femelles adultes est apparue élevée et stable, celles des faons femelles était basse, à cause de la prédation et de la stochasticité démographique. Les recommandations de gestion ont ainsi été axées sur la survie des jeunes. La population étudiée est isolée, entourée d'habitats non favorables, détruits par les activités humaines. Sa diversité génétique est parmi les plus basses de toutes les populations d'ongulés étudiées jusqu'à présent. D'apres la diversité allélique et l'hétérozygotie, les simulations pour estimer l'impact de la fragmentation ont indiqué une perte continue de diversité. La gestion du huemul de cette zone d'étude devrait au moins maintenir la taille de la population actuelle, augmenter l'aire protégée pour permettre la connexion avec les populations voisines, réduire la prédation des jeunes, et maintenir la survie actuelle des femelles adultes. Les futures recherches devraient s'attacher à la relation qu'a le huemul avec son habitat et ses prédateurs naturels. // Abstract : This research project used individual-based monitoring and molecular techniques to examine the social organization, life-history and population dynamics of huemul deer {Hippocamelus bisulcus) and provide knowledge useful for the conservation of this endangered species. The population at Lago Cochrane National Reserve, Chilean Patagonia, was monitored between March 2005 and June 2008. Deer (n = 55) were radiocollared, radio ear-tagged, and conventionally ear tagged to recognize individuals. Huemul social organization was analyzed using an index of association (the 'simple ratio'), to establish spatial and temporal association patterns of recognizable individuals of both sexes. Huemul formed small (mean ± SD: 1.68 ± 0.25 deer) mixed-sex groups throughout the year. I attributed this unusual association pattern to the low sexual dimorphism in body size, which should generate similar nutritional requirements and time budget for both sexes. Adult females may associate with each other based on kin relationships. Both sexes were highly philopatric and nonmigratory. Adult males avoid each other, and may benefit from associating with females by decreasing their risk of predation. Adult males that defended territories sired more fawns than nonterritorial males. Simulations of the finite rate of growth (A.) of the study population suggest that it is either stable or declining. Elasticity analysis showed that changes in adult female survival would have drastic effects on X. Adult female survival appeared high and stable but the survival of female fawns was low, because of predation and demographic stochasticity. Consequently, management recommendations were focused on young survival. The study population is isolated, surrounded by unsuitable habitats due to human-caused habitat destruction. Its genetic diversity is among the lowest of any ungulate population studied so far. Based on observed diversity of alleles and heterozygosity, simulations to estimate the impact of fragmentation indicated a continued loss in diversity. Management of huemul in the study area should at least maintain the current population size, increase the area protected to allow connection with other populations, reduce predation on fawns, and maintain current adult female survival. Future research should focus on the relationship of huemul with its natural predators and habitat. [Symboles non conformes

Mycobacterium avium subsp. paratuberculosis (MAP) infection in the endangered huemul deer (Hippocamelus bisulcus) in Patagonia

In a huemul (Hippocamelus bisulcus) population sympatric with cattle, we found evidence of Mycobacterium avium subsp. paratuberculosis (MAP) infection. Three huemul faecal pellet samples and two cows pats were collected and cultured for MAP presence. DNA was then extracted for PCR analysis of all signal-positive cultures. To assess whether MAP isolates obtained from huemul faeces were associated with typical MAP isolated from livestock, positive confirmed culture samples were sub-typed using a combination of five Mycobacterial Interspersed Repetitive Unit-Variable Number Tandem Repeat Analysis and one Short Sequence Repeat analysis markers. All faecal samples from both species were MAP positive. One huemul presented a different bacteria profile genotype not described before, suggesting that huemul and cattle in Patagonia could carry a unique MAP strain

Predicting the potential distribution of the Endangered huemul deer Hippocamelus bisulcus in North Patagonia

Habitat loss is one of the main threats to wildlife, particularly large mammals. Estimating the potential distribution of threatened species to guide surveys and conservation is crucial, primarily because such species tend to exist in small fragmented populations. The Endangered huemul deer Hippocamelus bisulcus is endemic to the southern Andes of Chile and Argentina. Although the species occurs in the Valdivian Ecoregion, a hotspot for biodiversity, we have no information on its occupancy and potential distribution in this region. We built and compared species distribution models for huemul using the maximum entropy approach, using 258 presence records and sets of bioclimatic and geographical variables as predictors, with the objective of assessing the potential distribution of the species in the Valdivian Ecoregion. Annual temperature range and summer precipitation were the predictive variables with the greatest influence in the best-fitting model. Approximately 12,360 km2 of the study area was identified as suitable habitat for the huemul, of which 30% is included in the national protected area systems of Chile and Argentina. The map of potential distribution produced by our model will facilitate prioritization of future survey efforts in other remote and unexplored areas in which huemul have not been recorded since the 1980s, but where there is a high probability of their occurrence

Behavioural Indicators of Intra- and Inter-Specific Competition: Sheep Co-Grazing with Guanaco in the Patagonian Steppe

In extensive livestock production, high densities may inhibit regulation processes, main- taining high levels of intraspecific competition over time. During competition, individuals typically modify their behaviours, particularly feeding and bite rates, which can therefore be used as indicators of competition. Over eight consecutive seasons, we investigated if variation in herd density, food availability, and the presence of a potential competitor, the guanaco (Lama guanicoe), was related with behavioural changes in domestic sheep in Chilean Patagonia. Focal sampling, instantaneous scan sampling, measures of bite and movement rates were used to quantify behavioural changes in domestic sheep. We found that food availability increased time spent feeding, while herd density was associated with an increase in vigilant behaviour and a decrease in bite rate, but only when food availability was low. Guanaco presence appeared to have no impact on sheep behaviour. Our results suggest that the observed behavioural changes in domestic sheep are more likely due to intraspecific competition rather than interspecific competition. Consideration of intraspecific competition where guanaco and sheep co-graze on pastures could allow management strategies to focus on herd density, according to rangeland carrying capacity

Evidence of Mycobacterium avium subsp. paratuberculosis (MAP) infection in huemul deer (Hippocamelus bisulcus) in patagonian fjords

In the Chilean coastal Patagonia, fourteen wild deer huemul faecal pellet samples were collected and cultured for Mycobacterium avium subsp. paratuberculosis detection. Six samples were positive, but only one was able to show a molecular type similar to the most common strain reported for cattle in Chile

Behavioural Indicators of Intra- and Inter-Specific Competition: Sheep Co-Grazing with Guanaco in the Patagonian Steppe

From MDPI via Jisc Publications RouterHistory: accepted 2021-11-17, pub-electronic 2021-11-22Publication status: PublishedFunder: Agencia Nacional de Investigación y Desarrollo; Grant(s): FONDECYT 1171039In extensive livestock production, high densities may inhibit regulation processes, maintaining high levels of intraspecific competition over time. During competition, individuals typically modify their behaviours, particularly feeding and bite rates, which can therefore be used as indicators of competition. Over eight consecutive seasons, we investigated if variation in herd density, food availability, and the presence of a potential competitor, the guanaco (Lama guanicoe), was related with behavioural changes in domestic sheep in Chilean Patagonia. Focal sampling, instantaneous scan sampling, measures of bite and movement rates were used to quantify behavioural changes in domestic sheep. We found that food availability increased time spent feeding, while herd density was associated with an increase in vigilant behaviour and a decrease in bite rate, but only when food availability was low. Guanaco presence appeared to have no impact on sheep behaviour. Our results suggest that the observed behavioural changes in domestic sheep are more likely due to intraspecific competition rather than interspecific competition. Consideration of intraspecific competition where guanaco and sheep co-graze on pastures could allow management strategies to focus on herd density, according to rangeland carrying capacity

Advanced Technologies for Oral Controlled Release: Cyclodextrins for oral controlled release

Cyclodextrins (CDs) are used in oral pharmaceutical formulations, by means of inclusion complexes formation, with the following advantages for the drugs: (1) solubility, dissolution rate, stability and bioavailability enhancement; (2) to modify the drug release site and/or time profile; and (3) to reduce or prevent gastrointestinal side effects and unpleasant smell or taste, to prevent drug-drug or drug-additive interactions, or even to convert oil and liquid drugs into microcrystalline or amorphous powders. A more recent trend focuses on the use of CDs as nanocarriers, a strategy that aims to design versatile delivery systems that can encapsulate drugs with better physicochemical properties for oral delivery. Thus, the aim of this work was to review the applications of the CDs and their hydrophilic derivatives on the solubility enhancement of poorly water soluble drugs in order to increase their dissolution rate and get immediate release, as well as their ability to control (to prolong or to delay) the release of drugs from solid dosage forms, either as complexes with the hydrophilic (e.g. as osmotic pumps) and/ or hydrophobic CDs. New controlled delivery systems based on nanotechonology carriers (nanoparticles and conjugates) have also been reviewed

Reconciling livestock production and wild herbivore conservation: challenges and opportunities

Increasing food security and preventing further loss of biodiversity are two of humanity’s most pressing challenges. Yet, efforts to address these challenges often lead to situations of conflict between the interests of agricultural production and those of biodiversity conservation. Here, we focus on conflicts between livestock production and the conservation of wild herbivores, which have received little attention in the scientific literature. We identify four key socio-ecological challenges underlying such conflicts, which we illustrate using a range of case studies. We argue that addressing these challenges will require the implementation of co-management approaches that promote the participation of relevant stakeholders in processes of ecological monitoring, impact assessment, decision-making, and active knowledge sharing

Dall’s sheep (Ovis dalli dalli Nelson, 1884) sexual segregation : interactions between two hypotheses

Four hypotheses have been proposed to explain sexual segregation in sexually dimorphic ungulates. I tested two of these on a Dall's sheep (CV/'s dalli dalli) population in Kluane National Park in Yukon, Canada. In the first, the reproductive-strategy hypothesis, males are predicted to feed in the best foraging areas to enhance their condition for intrasexual competition. Females are predicted to use areas with lower predation risk to raise offspring. In the second, the sexual dimorphism-body size hypothesis, females should use the best forage areas to satisfy the nutritional demands of gestation and lactation, and males due to their greater absolute metabolic requirements and larger body size have to forage on more available forages, but lower quality. I found Dall's sheep had a high social segregation but limited habitat segregation between males and females. Males were further from security cover in more gentle terrain than were maternal groups that used cliff or talus slopes. Maternal groups were located at higher altitudes than were males because most security cover was close to mountain peaks. Lamb presence was a factor increasing predation risk and affecting maternal groups' behaviour and distribution towards security cover. Group distance from security cover was negatively correlated with the proportion of individuals lying down for maternal groups without lambs. When this group type left security cover they were constantly active, either feeding or moving. The forage density index (FDI) values varied significantly, with the areas used by males having higher FDIs than areas used by maternal groups. Nutritional components were similar, but fibre content was significantly higher in areas used by males. Signs of wolves (Canis lupus) and predation events on Dall's sheep were recorded only at male sites. These data support the idea that male areas have a greater risk of predation. My results primarily support the reproductive-strategy hypotheses, indicating that predation plays a key role in the development of sexual segregation in Dall's sheep. However, I also found evidence to support one prediction of the sexual dimorphism-body size hypothesis, where males use areas higher in forage availability but lower in quality than female areas.Land and Food Systems, Faculty ofGraduat