Salinity tolerance explains the contrasting phylogeographic patterns of two swimming crabs species along the tropical western Atlantic

Unexpected Absence of Population Structure and High Genetic Diversity of the Western Atlantic Hermit Crab Clibanarius antillensis Stimpson, 1859 (Decapoda: Diogenidae) Based on Mitochondrial Markers and Morphological Data

“…Many marine species have populations widely distributed with low genetic differentiation and habitats interconnected by gene flow [8]. Some examples among decapods distributed along the western Atlantic can be mentioned: the slipper lobsters Scyllarides brasiliensis Rathbun, 1906 [90], the mangrove crab Ucides cordatus Linnaeus, 1763 [24,91], the swimming crab Callinectes danae Smith, 1869 [22] and the congeneric species Clibanarius sclopetarius [27]. The absence of genetic structure within these species, as well as among specimens of C. antillensis from different localities, may be explained by the lack of physical barriers restricting gene flow and by their larval dispersive capacity [92].…”

“…It may influence biochemical composition, growth, survival and development of larvae [100,101], feeding activity [19], carbon accumulation rates [102], as well as osmoregulatory activities [103]. In fact, salinity has been described as a barrier for dispersion and gene flow of some decapod's species [22,26,104,105]. In those studies, the absence of gene flow between populations resulted from the incapacity of their larvae to traverse the Amazon River plume at the Atlantic Ocean, where the volume of water discharged changes the local salinity.…”

“…On the other hand, the outflow of the Amazon River has not been a barrier for the dispersal of other decapods [22,91] since the larvae may be more tolerant to low salinity. This might be the case of C. antillensis larvae, which can develop at salinity levels of 29-35 ppt [34,35].…”

“…However, some studies revealed that high levels of connectivity and genetic homogeneity were not necessarily related to the duration of planktonic stages [10][11][12]. In addition, gene flow may also be influenced by marine currents circulation, local oceanic conditions, physical barriers, food availability, ecological interactions, as well as past geological events and recent history [8,10,[13][14][15][16][17][18][19][20][21][22].…”

“…Diversity 2021, 13, 56 2 of 28 essarily related to the duration of planktonic stages [10][11][12]. In addition, gene flow may also be influenced by marine currents circulation, local oceanic conditions, physical barriers, food availability, ecological interactions, as well as past geological events and recent history [8,10,[13][14][15][16][17][18][19][20][21][22]. Therefore, each marine species has its own patterns of gene flow and genetic differences along its distribution [14,23].…”