BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Talks.cam//talks.cam.ac.uk// X-WR-CALNAME:Talks.cam BEGIN:VEVENT SUMMARY:Contributed Talk: Modelling host-associated microbiota over host evolutionary time - Guilhem Sommeria-Klein (University of Turku) DTSTART:20221014T135000Z DTEND:20221014T141000Z UID:TALK179432@talks.cam.ac.uk DESCRIPTION:Co-authors: Hé\;lè\;ne Morlon\, Benoî\;t P&ea cute\;rez-Lamarque\, Leo Lahti\nUnderstanding the evolution of host-associ ated microbiota requires accounting for the phylogenetic history of their hosts\, because microbiota are transmitted across host generations and bec ause evolutionarily conserved host traits influence microbiota composition . To understand microbiota evolution from large-scale data\, we developed an approach to model the changes in microbiota composition through time al ong the phylogenetic tree of the hosts\, where microbiota composition is c haracterized as the relative abundances of higher-level microbial taxa. We did so by leveraging existing approaches for modelling the evolution of m ultivariate phenotypic traits. Our approach provides a model-based quantif ication of phylosymbiosis\, i.e.\, the propensity of microbiota compositio n to reflect the evolutionary divergence between hosts. It also infers the covariations between microbial taxa abundances through time and reconstru cts the microbiota composition of the hosts&rsquo\; common ancestors along the tree. We can then estimate the influence of covariates such as diet o n the retrieved patterns. This approach may be applied over deep evolution ary time\, e.g.\, to the microbiota of all mammals\, or on a shorter times cale\, e.g.\, to the microbiota of humans. We applied it to the gut microb iota of mammals and birds (215 and 323 species covering the entire phyloge netic tree\, respectively). We found significant levels of phylosymbiosis in both mammals and birds\, which cannot be fully explained by diet conser vatism\, and we reconstructed a microbiota composition consistent with an insectivorous diet for the ancestor of all mammals. We are now developing an extended model that accommodates microbial composition data at a higher taxonomic resolution by grouping microbial taxa into assemblages\, and we are investigating the application of our approach to the human gut microb iota. LOCATION:Seminar Room 1\, Newton Institute END:VEVENT END:VCALENDAR