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RESEARCH PRODUCT

Heterogeneity of host-parasite relationships : ecological and evolution significance

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description

Although parasites have been studied for a long time, the major knowledge concern parasite which have medical or veterinary interest. Whereas they are omnipresent in the nature, the role of parasite infections on natural populations is poorly understood. One of the aim of this work was to study the pathogenicity of two groups of parasites (ticks and Haemosporidae) among natural populations of blackbirds. The study revealed that both parasites are associated with body condition and immune response. However, the study of an urban blackbird population did not confirm the effect of Haemosporidae on the survey and on the population dynamic.The impact of spatial pattern on the relation between host and parasites has also been studied because blackbird is an ubiquitous specie. We showed that urban population suffer from weaker parasite infection than forest population. This result could partly explain the strong density observed in urban areas, even if other explanations are obviously possible.At last, recent studies suggest that carotenoids could be the link between the immunity of male and the intensity of coloration. However, those studies used immune assay. This method has been recently debated because challenges could not mirror the parasite resistance. Our results showed the same way. Moreover, this work seems to show that social context influence the relation between immunity and coloration. This brings into question the idea that carotenoids are a universal mechanism which guarantee the honesty of signal.