Cytochrome b analyses
Mitochondrial sequences provided information about the haplotypes present in each area and, together with θST differentiation index, we were able to indicate which areas have the same source population. We identified six haplotypes among all sampled populations (GenBank accession number: XXXXX). Three of them have been sampled on native range by Austin et al. (2004), two by Kamath et al. (2016) and one by Bai et al. (2012) on invasive areas of the USA and China. Another three haplotypes were sampled for the first time in the present work. The genetic diversity for each site is available on Table 2.
The population differentiation test was significant following the Benjamini and Hochberg procedure for all comparisons except Minas Gerais (MG)–Cuba, Brazil–Ecuador, and Singapore–Japan–China (Table 3). These results suggest that each of these groups have the same native origin and, for this reason, they were pooled together for the AMOVA. Belgium and Singapore were also nearly significant (0.05307), but were not pooled together as Belgium differentiates from the other Asian countries. AMOVA results showed similar covariance results between native range areas (Cuba + MG: 18.41 – 20.18; Asian countries: 24.05 – 31.01; Brazil + Ecuador: 17.68 – 26.26; Belgium: 0.00 – 7.87. (Table 4)).
Our phylogenetic analysis recovered topologies congruent with those reported by Kamath et al. (2016), with USA native west and east clades as monophyletic groups. Our haplotypes H02, H03, H04 and H06 are clustered in the western lineage; whereas haplotypes H01 and H05 are clustered in the eastern lineage.