Molecular analysis of the invasive populations of Urochloa (Poaceae) in a large Neotropical reservoir

Abstract Urochloa is the most diverse genus of the Melinidinae, Paniceae tribe, Panicoideae subfamily. Different species of Urochloa were introduced into Brazil, where they occur in a variety of habitats, including rivers and reservoirs such as, for example, the Itaipu Hydroelectric reservoir. The effects of Urochloa arrecta on native diversity have previously been investigated in the Upper Parana basin but the correct identification of the species of those samples is still doubtful, due to its morphological similarity with other Poaceae species in the region and weakness of characters for its separation from Brachiaria. In this study we have characterized molecularly and evaluated the phylogenetic variability of Urochloa arrecta populations occurring in the Itaipu Reservoir using the ITS1 nuclear marker and atpF and trnL-trnF plastid markers. We compared them with sequences available at the GenBank (NCBI) to confirm the correct identity of this taxon. The results indicate that the individuals analyzed belong to the species U. arrecta. There was absence of genetic variation for the populations sampled in Itaipu and they presented genetic similarity to specimens collected from aquatic ecosystems located over a range of at ca. 700 km from Itaipu.