earticle

영어

Unnatural dispersal and translocation through human mediated contribute to the range expansion of Asian black-spined toads, Duttaphrynus melanostictus. The species became invasive in numerous ecosystems, such as Madagascar and the Wallacean islands area, where it has a strong ecological impact. Here, using Taiwan as a case study to examine inadvertent translocations of D. melanostictus through growing trade and the geographically central position of the island, we retrace the origin of D. melanostictus using parsimony networks together with Bayesian phylogenetic and population clustering approaches. We tested four major dispersal hypotheses to explain the relation between the Taiwanese and other D. melanostictus populations: 1) the species originates from South East Asia (SEA) and it is invasive in Taiwan as a result of human-induced dispersal, 2) the species originates from South East Asia, and dispersed over land bridges, 3) the species comes from the Chinese mainland through human-induced dispersal, 4) the species originates from the Chinese mainland, and dispersed over land bridges during glacial maxima. Our unrooted haplotype network based on a fragment of contiguous tRNA Gly-ND3 mitochondrial DNA from 22 individuals, together with homologous sequences extracted from GenBank for China and SEA, confirmed the non-clustering of haplotypes from SEA and Taiwan. Likewise, Bayesian phylogenetic inferences further clarified the absence of genetic segregation between Taiwanese and mainland Chinese populations. The haplotypes from Taiwan were segregated within a monophyletic clade, shared with mainland Chinese populations. The origin of the Taiwanese D. melanostictus is consequently linked to the Chinese clade and rejects our first and second hypothesis. The clustering with haplotypes from geographically close localities in mainland China, as well as with haplotypes present in geographically distant but active trading areas, here Hong-Kong, suggests both past dispersion over land-bridges, and recent human-induced dispersal.