Comparative phylogeography and genetic connectivity of two crustacean species with contrasting life histories on South Atlantic sandy beaches.

The life histories of species influence the connectivity between populations, for example the dispersal potential, fecundity, and population size. We compare the phylogeography and genetic connectivity of two sandy-beach crustaceans with contrasting dispersal potentials and population traits in Brazil, based on the 16S mitochondrial gene. While the ghost crab Ocypode quadrata possesses high fecundity, long-lived planktonic larvae, and lower population densities of adults, the isopod Excirolana braziliensis is a brooder with low fecundity and higher population densities. Phylogenetic analysis of haplotype networks yielded contrasting results for the two species. Four different lineages were observed for E. braziliensis, while O. quadrata showed a low genetic structure, sharing haplotypes over ~ 7,000 km. For the isopod, the two most frequent lineages (‘North A’ and ‘South A’ lineages) showed distribution range limits that agreed with the tropical-subtropical transition of 22°S, while the others were sympatric, less frequent, and uncommon. While the ‘North A’ showed high haplotype diversity with a high structure, the ‘South A’ showed shared haplotypes and low genetic structure. Our results suggest that the contrasting life histories affect the population connectivity and genetic structure. The genetic patterns of the two species should be considered in the management and conservation of sandy-beach ecosystems. [ABSTRACT FROM AUTHOR]