Recent studies have improved our understanding
of Amazonian geological history during the late Tertiary
and Quaternary, two periods regarded as critical for the
recent diversification of the Amazonian avifauna. The
notion that geologically older and more stable areas of
Amazonia (such as the Brazilian and Guianan shields)
functioned as ‘‘species-pumps’’, whereas geologically more
dynamic areas (such as the western Amazonian lowlands)
mostly ‘‘captured’’ part of the diversity generated nearby,
was supported by a recent phylogeographic study focusing
on a species complex of the genus Xiphorhynchus (Dendrocolaptidae).
Here, we review several additional
molecular datasets to assess whether this historical scenario
can be extended to other lineages of Amazonian birds as
well. The datasets reviewed indicated that most lineages of
upland forest species found nowadays in western Amazonia
are associated with more basal lineages from the Brazilian
shield, Guianan shield, and the Andes, indicating a more
recent history in this geologically dynamic region. Conversely,
lineages associated with seasonally flooded forests
seem to have an ancient history in western Amazonia,
apparently expanding over the geologically more stable
areas only recently. Most sister taxa of the lineages
reviewed exhibited levels of pairwise sequence divergence
consistent with splitting events dating back to a time frame
stretching from the late Miocene to the early Pleistocene, a
period when significant physiographic and landscape
changes took place in Amazonia. When interpreted together,
all the studies reviewed provide evidence that geology
and landscape evolution are tightly linked with the timing
and mode of differentiation of Amazonian birds.
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