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sur le développement des zones arides et semi-arides

Titre : Immunity of cheetahs (Acinonyx jubatus) : an evolutionary, comparative and life history perspective

Die Immunantwort von Geparden (Acinonyx jubatus) aus evolutionärer, vergleichender und lebensgeschichtlicher Perspektive

Auteur : Heinrich, Sonja Kirsten

Université de soutenance : Freien Universität Berlin

Grade : Doctor of Philosophy (PhD) 2017

Résumé partiel
The cheetah (Acinonyx jubatus, family : Felidae order : Carnivora) was once widely distributed across Africa and Asia but has been extirpated from a large portion of this area. Major threats are considered to be habitat loss and fragmentation, competition with other carnivore species, their killing as livestock predators and high disease susceptibility associated with low genetic diversity. Low genetic diversity may result in populations being more vulnerable to new pathogens, especially if the immune genes of the major histocompatibility complex (MHC) are affected. Cheetahs have been described as a classic example for the negative consequences of genetic uniformity in the MHC in numerous textbooks on conservation genetics and in scientific publications. A recent study using single-strand conformation polymorphism analysis has confirmed earlier studies and reported low genetic diversity at MHC class I and MHC class II in cheetahs. However, high disease susceptibility has only been reported for captive cheetahs, whereas free-ranging cheetahs exhibit a good overall health status. Whether low genetic diversity at the MHC is of relevance for the conservation of the cheetah has been controversially discussed. This thesis has been designed to examine the immunological architecture of the cheetah and assess its immune parameters both in comparison with other sympatric carnivore species (chapter 2 and 3) as well as a function of life history attributes and its living environment (chapter 4). This thesis is embedded in a long-term research project on cheetahs in central Namibia, through which blood samples from approximately 400 cheetahs and other carnivore species were collected since 2002 and made available for this study. In chapter 2 I compare the constitutive innate immune part of six sympatric African carnivore species using a functional test, the bacterial killing assay (BKA). To compare different species, I first adapted the classical BKA protocol in such a way that the same dilutions and bacterial concentrations could be applied to all species. I demonstrated that feline species had a constitutive innate immune response of at least one magnitude higher than those of canine species. Cheetahs and caracals (Caracal caracal) had a higher bacterial killing capacity than the other four carnivore species studied and also than species of other taxa which had been investigated in previous studies. In chapter 3 I compare six humoral immune parameters of the cheetah to those of the sympatric leopard (Panthera pardus), which exhibits the highest genetic diversity amongst felines, including the MHC. The strength of the constitutive innate immune system was higher in cheetahs than in leopards. In contrast, leopards exhibited a stronger induced innate and adaptive immune system than cheetahs. These results suggest different immune investment strategies employed by the two species, possibly as a consequence of the differences in MHC diversity in the two species. M

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