Predicting lifestyle and host from positive selection data and genome properties in oomycetes

Host and niche shifts are a source of genomic and phenotypic diversification as evidenced in parasitism. Most characteristic is metabolism reduction as parasites adapt to a particular host. However, selection pressures acting on such organisms are not fully understood. Here, we developed a comparative genomic approach to study underlying adaptive trends in oomycetes, eukaryotes with a broad range of economically important parasitic lifestyles. Our analysis reveals converging evolution on biological processes for oomycetes with similar niche and host. We find that certain functions, in particular carbohydrate metabolism, transport, and signaling, are important for host and environmental adaption in oomycetes. Given an increasing availability of fungal and oomycete genomes from environmental samples, we have developed a model for the prediction of filamentous pathogen lifestyles based on genome properties. Understanding how genomes and selective pressures correlate with lifestyle may be crucial to identify new emerging diseases and pandemic threats.