Phylogeography of the flathead mullet Mugil cephalus species complex – Using Next-Generation RAD-Sequencing to highlight a worldwide marine dispersion
Final Report Abstract
The goal of the present project was to infer the phylogenetic relationships within the Mugil cephalus species complex, reconstruct their biogeographic history, and evaluate morphological and morphometric data useful for species identification. At the beginning of the project, genetic samples of the 16 then known genetic lineages were evaluated and prepared for further analyses. A total of 38 samples were sequenced in a wholegenome-shotgun analysis. A reference genome was used for evaluation of sequencing results. After qualitative filtering and data processing, the phylogenetic relationships of the Mugil cephalus species complex were inferred based on a maximum likelihood approach. The interrelationships of the Mugil cephalus species were thoroughly resolved and supported by strong bootstrap values. Within the evolutionary history of the species complex, two subgroups evolved early on, one present in the West Atlantic and East Pacific and the other in the East Atlantic and Indo-Pacific. The time calibration of the phylogeny revealed that the species complex only started to diversify about 3.8 million years ago. Further speciation events took place within a short time frame thereafter. Based on the previous results, the biogeographic history of the Mugil cephalus species complex was reconstructed using a variety of different models which accounted for the current distribution of the species as well as paleogeographical events among other things. The reconstruction showed that evolutionary history of the species complex was heavily influenced by paleoclimatic events. It is likely that the beginning of diversification was triggered by rising temperatures in the Caribbean Sea and the intensification of the gulf stream caused by the closure of the Isthmus of Panama. Further, alternating cold and warm periods during the Mid and Late Pliocene influenced the expansion and subsequent disruption of species’ distribution areas leading to speciation. During the whole project, morphological and morphometric data of all Mugil cephalus species was collected from numerous specimens. Evaluation of this data has shown that morphological data has almost no relevance for species delineation. Morphometric data on the other hand can be used for taxonomical purposes, however, only few morphometric relationships are helpful in species with overlapping distribution ranges.
Publications
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Contributions to the Taxonomy of the Mugilid Genus Moolgarda Whitley (Teleostei: Mugilidae), with Redescriptions of M. crenilabis, M. seheli and M. tade from the Red Sea. Diversity, 16(6), 325.
Bogorodsky, Sergey V.; Thieme, Philipp; Senou, Hiroshi; Mahmoud, Zuheir N.; Alpermann, Tilman J. & Durand, Jean-Dominique
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Die Phylogeographie des Mugil cephalus Artkomlpexes. 20. Tagung der Gesellschaft für Ichthyologie (Präsentation).
Thieme P., Reisser C., Leprieur F. & Durand J.-D.
