Morphology and genetic investigation of flatfish interspecies hybrids (Pleuronectes platessa X Platichthys flesus) from the Baltic Sea Item Type Article Authors He, Song; Mork, Jarle; Larsen, William B.; Møller, Peter R.; Berumen, Michael L. Citation He, S., Mork, J., Larsen, W. B., Møller, P. R., & Berumen, M. L. (2020). Morphology and genetic investigation of flatfish interspecies hybrids (Pleuronectes platessa X Platichthys flesus) from the Baltic Sea. Fisheries Research, 225, 105498. doi:10.1016/j.fishres.2020.105498 Eprint version Pre-print DOI 10.1016/j.fishres.2020.105498 Publisher Elsevier BV Journal Fisheries Research Rights NOTICE: this is the author’s version of a work that was accepted for publication in Fisheries Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Fisheries Research, [[Volume], [Issue], (2020-01-28)] DOI: 10.1016/ j.fishres.2020.105498 . © 2020. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http:// creativecommons.org/licenses/by-nc-nd/4.0/ Download date 01/10/2021 00:51:14 Link to Item http://hdl.handle.net/10754/661363 FIGURES Figure 1 Map of the sampling locations and putative geographic distribution ranges of flounder Platichthys flesus (green and purple), plaice Pleuronectes platessa (green), and cryptic species Platichthys solemdali (yellow, purple, and potentially southern Baltic Sea) which was recently identified as distinct from flounder. The distribution ranges of these flounder and plaice were mostly overlapped (green) except in the northeast part of the Baltic Sea (purple). Grey shading indicates land. Black shading indicates the bottom salinity of these area are 11-18 psu and the bottom salinity of the rest of area inside the Baltic Sea is lower than 11 psu (Momigliano et al., 2018). Collection sites are indicated by black stars on the map. Plaice and flounder were observed to co-existing in all the sampling locations. Hybrids were only observed from three locations during this study, which are indicated by a white dashed circle, in the western boundary of the Baltic Sea. White star on the map indicate the hybridization spot suggested by Kijewska et al. (2009). Fish photo credit to Henrik Carl, Paolo Momigliano, and Henri Jokinen. Figure 2 Phylogenetic relationships of flounder Platichthys flesus and plaice Pleuronectes platessa, and putative hybrids haplotypes represented in median-joining networks of mitochondrial marker COI (e and f) and network-based haploweb (Flot et al., 2010) of the TMO-4c4 (a and b), and phtrP (c and d). Left column (a, c, and e) are the network/haplowebs without the hybrid samples and right column (b, d, and f) are the network/haplowebs contained the hybrid samples haplotypes. Each circle represents a unique haplotype and size of the circle is proportional to its total frequency. The red rhombus represents the missing haplotype. Each branch connecting different circles represents a single nucleotide substitution; black cross-bar on them represents an additional nucleotide substitution; black double bars represents more than 15 nucleotide substitutions and the exact numbers are as indicated; red cross-bar on them represents a nucleotide insertion/deletion. The dashed line circles represent mutually exclusive gene pool of two species. Curves connecting branches indicate these haplotypes occurring in heterozygous individuals. Colors denote sample species and geographic origin as indicated by the legend. The heterozygote samples which break the mutually exclusive gene pool were nominated on the curves by black arrows and sample IDs. Figure 3 PCA scatter plot (left) and STRUCTURE plot (right) of flounder Platichthys flesus, plaice Pleuronectes platessa, and putative hybrids. PCA plot were generated based on microsatellites and nuclear markers (TMO-4c4 and pthrP). The dots represent Individual genotypes and the identity categories for genotypes of each individual are indicated in the legend. The 99% inertia ellipses represent the genetic variations within each species categories. The eigenvalues plots show the amount of genetic information retained by each successive function. Delta K value chart had shown the best cluster number is K=2 according to the Evanno method(Earl & von Holdt, 2012). The posterior probability of assignment of plaice, flounder, and hybrid samples to one of two (K=2) genotype clusters were shown in the STRUCTURE plot, which generated by Bayesian clustering analysis of microsatellite genotypes. The samples which suggested as hybrids were nominated by their sample IDs. Earl, D.A. & von Holdt, B.M. (2012) STRUCTURE HARVESTER: a website and program for visualizing STRUCTURE output and implementing the Evanno method. Conservation Genetics Resources, 4, 359-361. Flot, J.-F., Couloux, A. & Tillier, S. (2010) Haplowebs as a graphical tool for delimiting species: a revival of Doyle's" field for recombination" approach and its application to the coral genus Pocillopora in Clipperton. BMC Evolutionary Biology, 10, 372-386. Kijewska, A., Burzyński, A. & Wenne, R. (2009) Molecular identification of European flounder (Platichthys flesus) and its hybrids with European plaice (Pleuronectes platessa). ICES Journal of Marine Science: , 66, 902-906. Momigliano, P., Denys, G.P., Jokinen, H. & Merilä, J. (2018) Platichthys solemdali sp. nov.(Actinopterygii, Pleuronectiformes): a new flounder species from the Baltic Sea. Frontiers in Marine Science, 5, 225. .