Population Structure of Rhizophora mangle, Rhizophora racemosa and Rhizophora harrisonii (Rhizophoraceae) from the Brazilian Coastal Zone

The mangrove forests occurs in estuarine regions.  For its conservation, it is essential to understand about the biology of the species that compound this environment. This study is focused on the investigation of population structure for three species of mangle from Brazil: Rhizophora mangle,  Rhizophora racemosa and Rhizophora harrisonii. We used 10 microsatellite markers, developed by our research group, to study the structure of 13 R. mangle populations from the Brazilian coast.  It was identified genetic diversity across populations (F_st = 0.290) and a lower level among individuals from the same population (F_is = -0.162). In the state of Pará we found the highest allelic richness (3.080).  The Structure 2.3.1 and Structure Harvester v 0.6.8 were used to calculate how the gene pool is distributed among the populations. Two distinct groups were found. The first is composed by individuals from Pará, Maranhão, Piauí e Ceará, and the second  by individuals from the other states. For Rhizophora racemosa and Rhizophora harrisonii we used four microsatellite markers in four populations from the states of Pará and Piauí. We discovered genetic differentiation between populations (F_st = 0.174;  F_is = -0.105 e F_it = 0.087). The results showed a lower genetic diversity in populations in the South compared to the North of the Brazilian coast. This genetic diversity would be explained by consecutive founder events followed by subsequent colonization occurred on these regions as a result of rising temperature by the end of the last glacial period.