Introduction pathways and evolutionary mechanisms of the spread of alien species of Lolium on sandy coasts in Japan

1. Estimating the role of specific processes in the spread of alien species necessitates the determination of introduction pathways and source populations of invaded areas. Alien grasses in the genus Lolium that have become widely invasive in Japan provide provides a unique opportunity to estimate the expansion process through a direct comparison between source and naturalised populations because the introduction pathways, contaminants in grain commodities and commercial cultivars for fodder crops or revegetation materials are well-known. Therefore, by directly comparing between source and naturalised populations, we estimated the introduction pathways and whether adaptative evolution occurred in Lolium species on sandy coasts in Japan.
2. Lolium individuals sampled from naturalised populations in croplands, seaports and sandy coasts were compared with those from two introduction sources for morphological and genetic variations based on a genome-wide single nucleotide polymorphism analy...