Cryptic species, native populations and biological invasions by a eucalypt forest pathogen

Human associated introduction of pathogens and consequent invasions are very evident in areas where no related organisms existed before. In areas where related but distinct populations or closely related cryptic species already exist, the invasion process is much harder to unravel. In this study, the population structure of the Eucalyptus leaf pathogen Teratosphaeria nubilosa was studied within its native range in Australia, including both commercial plantations and native forests. A collection of 521 isolates from across its distribution was characterized using eight microsatellite loci, resulting in 112 multilocus haplotypes (MLH). Multivariate and Bayesian analyses of the population conducted in STRUCTURE revealed three genetically isolated groups (A, B and C), with no evidence for recombination or hybridization among groups, even when they co-occur in the same plantation. DNA sequence data of the ITS (n=32), β-tubulin (n=32) and 27 anonymous loci (n=16) were consistent with microsat...