Resumen: Ticks are vectors of pathogens affecting human and animal health worldwide. Nevertheless, the ecological and evolutionary interactions between ticks, hosts, and pathogens are largely unknown. Here, we integrated a framework to evaluate the associations of the tick Ixodes ricinus with its hosts and environmental niches that impact pathogen circulation. The analysis of tick-hosts association suggested that mammals and lizards were the ancestral hosts of this tick species, and that a leap to Aves occurred around 120 M years ago. The signature of the environmental variables over the host''s phylogeny revealed the existence of two clades of vertebrates diverging along a temperature and vegetation split. This is a robust proof that the tick probably experienced a colonization of new niches by adapting to a large set of new hosts, Aves. Interestingly, the colonization of Aves as hosts did not increase significantly the ecological niche of I. ricinus, but remarkably Aves are super-spreaders of pathogens. The disparate contribution of Aves to the tick-host-pathogen networks revealed that I. ricinus evolved to maximize habitat overlap with some hosts that are super-spreaders of pathogens. These results supported the hypothesis that large host networks are not a requirement of tick survival but pathogen circulation. The biological cost of tick adaptation to non-optimal environmental conditions might be balanced by molecular mechanisms triggered by the pathogens that we have only begun to understand. Idioma: Inglés DOI: 10.3389/fcimb.2017.00234 Año: 2017 Publicado en: Frontiers in cellular and infection microbiology 7, MAY (2017), 234 [11 pp] ISSN: 2235-2988 Factor impacto JCR: 3.52 (2017) Categ. JCR: MICROBIOLOGY rank: 40 / 125 = 0.32 (2017) - Q2 - T1 Categ. JCR: IMMUNOLOGY rank: 64 / 155 = 0.413 (2017) - Q2 - T2 Factor impacto SCIMAGO: 1.703 - Medicine (miscellaneous) (Q1) - Infectious Diseases (Q1) - Microbiology (medical) (Q1) - Microbiology (Q1) - Immunology (Q2)