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.