4.3 Conclusion: implications of DNA barcoding to accelerate biogeography research
As different analytical methods have different theoretical foundations, it is advisable to test a wide variety of approaches of species delimitation, and to favor patterns that are congruent across the results. Moreover, the contrast of different methods helps to comprehend their propensity to either split or lump clusters. We evaluated some approaches for species delimitation in the genus Polypedilumthrough single-locus DNA barcodes and found the sGMYC as the method more adequate to estimate putative species on our dataset. Our results highlight Polypedilum as species-rich genus, yet incompletely documented, which implies in the need of increased taxon sampling, across geographical ranges, and the use of additional molecular data for greater resolution when using molecular species delimitation approaches for the group. Quantitative species delimitation methods are sensitive to sampling effort. Since communities typically contain several species that are locally rare, observed species richness provides just an underestimate of the diversity actually present, except if the community is thoroughly sampled. Therefore, a reference COI sequence library derived from expert-identified reference material is fundamental to assign organisms into species by matching the sequence of an unknown sample to the reference library. Our hypothesis that there would be substantial differences in community structure between thePolypedilum fauna in South America and other neighboring regions, particularly the Nearctic region, was confirmed. The Neotropical region exhibited high levels of endemism and richness for Polypedilumspecies. Despite major advances in our understanding of Neotropical biodiversity in recent years, several questions remain to be answered: When did the Neotropics reach globally outstanding levels of species richness? Why do nearly all groups of organisms have more species in the Neotropics? What drives latitudinal patterns of diversity? When did the species observed today split from their most recent common ancestors? Further biological and geological data, associated with the integration of different DNA-based methods for estimating species richness, will advance the field of natural history and increase our ability to make knowledge-based decisions in conservation issues. The integration of biodiversity genomics in biogeography science therefore represents a major scientific priority.