Abstract
Barriers to gene flow (BGF) play a pivotal role in the dynamics of
population genetics promoting genetic differentiation, thus, are
inexorably associated with the development and maintenance of
phylogeographic structure. Phylogeographic structure resulting from BGF
represents data that help the management of natural genetic resources,
aiding in the recognition of areas of conservation interest. Several
geographic and oceanographic processes found along the Brazilian coast
have been proposed as BGF. However, no consensus exist identifying which
of them represents the most important in shaping biodiversity.
Therefore, this study provides a synthesis of the scientific literature
on Brazilian marine phylogeography and used published data to build
datasets that allowed us apply linear (lm ) and generalized
additive models (gam ) to identify spatially congruent
phylogeographic breaks among marine species (as areas of high BGF
frequency occurrence). Lm identified a significant negative
correlation between the occurrence of BGF and latitude, suggesting that
population in the tropics are genetically more structured than in higher
latitudes. This result bears strong association with the latitude
species diversity gradient observed worldwide. Gam identified
Cape São Roque (05° 28’ S) as the main BGF for populations with
continuous distribution along the Brazilian coast. Cape São Roque is
located near the center point region where the South Equatorial Current
splits into the northward North Brazil Current and the southward Brazil
Current. This study represents the first literature synthesis of
Brazil’s marine phylogeography and provides a novel explicit
quantitative approach to comparative phylogeography.