Genetic exchange and emergence of novel strains in directly transmitted trypanosomatids

► Crithidia bombi are directly transmitted trypanosomatids that infect many species of bumblebees. In nature, they are genetically highly diverse. ► We here show experimentally that different strains of C. bombi undergo genetic exchange when co-infecting a natural host. ► Offspring strains of such exchanges are either recombinants that correspond to Mendelian expectations, strains that have lost alleles, or strains that have novel genotypes. ► The experiment shows that genetic exchange in C. bombi is frequent.