From the mountains to the sea: phylogeography and cryptic diversity within the mountain mullet, <i><scp>A</scp>gonostomus monticola</i> (<scp>T</scp>eleostei: <scp>M</scp>ugilidae)

Abstract

Abstract Aim The mountain mullet, A gonostomus monticola , is a diadromous fish widespread throughout M iddle A merica, occurring in rivers along the A tlantic and P acific slopes, as well as in the W est I ndies. Based on the disjunct distribution of this species, it has been hypothesized that this fish may represent more than one taxon. The purpose of this study was to conduct a robust phylogeographical analysis of A . monticola across its range, using mitochondrial and nuclear markers. We aimed to investigate the potential for cryptic diversity and the time‐scale of divergence in an effort to elucidate biogeographical episodes within M iddle A merica in relation to the evolutionary history of A gonostomus monticola . Location North and M iddle A merica, including the W est I ndies. Methods Mitochondrial and nuclear sequence data (cyt b , S7 ‐1) from individuals throughout the range of the species were analysed phylogenetically using maximum‐likelihood methodology. The oldest known fossil mullet was used as a calibration to investigate divergence times for clades within A . monticola . Results Results indicate four distinct lineages within the known range of A . monticola that largely correspond to oceanic basins ( C aribbean, G ulf of M exico, P acific‐A, P acific‐B). Divergence time estimates indicate early to mid‐ M iocene divergences for all four A . monticola clades, with O ligocene to M iocene divergences of internal nodes. Main conclusions These findings are congruent with geological hypotheses regarding movement of the C hortís block, as well as recent studies on the age of beginning emergence of the P anama A rc.