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.