The paper this week is from PLoS Genetics, concerning the mechanisms of adaptation of Bartonella spp. to their mammalian hosts.

The PLoS journals give a good accessible overview of there papers so here is the author summary:

Adaptive radiation is the rapid origination of an array of species by the divergent colonization of disparate ecological niches. In the case of pathogenic bacteria, radiations can lead to the emergence of novel human pathogens. Being divergently adapted to a range of different mammalian hosts, including humans as reservoir or incidental hosts, the genus Bartonella represents a suitable model to study genomic mechanisms underpinning divergent adaptation of pathogens. Here we show that two distinct lineages of Bartonella have radiated in parallel, resulting in two arrays of evolutionary distinct species adapted to overlapping sets of mammalian hosts. Such parallelisms display excellent models to reveal insights into the genetic mechanisms underlying these independent evolutionary processes. Our genome-wide analysis identifies a striking evolutionary parallelism in a horizontally-acquired protein secretion system in the two lineages. The parallel evolutionary trajectory of this system in the two lineages is characterized by the convergent origination of a wide array of adaptive functions dedicated to the cellular interaction within the mammalian hosts. The parallel evolution of the two radiating lineages on the ecological as well as on the molecular level suggests that the horizontal acquisition and the functional diversification of the secretion system display an evolutionary key innovation underlying adaptive evolution.

Discussion points

  1. Were the aims of the study clear?
  2. Were the findings clearly supported by the data?
  3. What relevance does understanding the mechanisms driving diversification have for human health?
  4. Could any additional experiments improve the study?
 Join us for discussion Tuesday 25th September at 8pm UK time for #microtwjc
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