Coptodon (Perciformes: Cichlidae) species living in Koyceğiz lake and Kocagol: Diagnosis in the light of genetic and morphological data

Species belonging to the Coptodon genus from the Cichlidae family from Lake Köyceğiz and Kocagöl, which are located on the South Aegean coasts of Turkey were introduced, but it has not known exactly which species, when and how they were transported. Conflicting in cichlid species names have been reported in the literature for many years, especially for Köyceğiz Lake. In order to develop the right management and conservation strategies, first of all, it is necessary to clearly define the species of the cichlid fish, which creates dense populations in both lake systems. In this study, which was prepared in this direction, it is aimed to (i) identify of species from current populations of Coptodon with reference to existing data in GenBank, and estimation of the source population using genetic data, (ii) reveal the morphological difference/similarity patterns within and between lakes in the context of morphometric and meristic characters. The mitochondrial control region (D - loop) was chosen as a molecular marker for genetic analysis of a total of 93 individuals previously caught from both lakes and Peçenek drainage channels and sequence analyzes were carried out. Maximum likelihood (maximum likelihood, ML) and Bayesian Phylogenetic (BF) approaches were used for phylogenetic analysis. Besides, in order to determine the morphological patterns, 26 morphometric and 6 meristic characters of 170 individuals were measured and multivariate analyzes were made. As a result of haplotype analysis performed among D-loop gene sequences, a total of 3 haplotypes were determined in Coptodon populations. These are respectively; 2 (H2-H3) haplotypes for Köyceğiz Lake, 2 (H2-H3) for Kocagöl and 1 (H1) for the Peçenek drainage channel. Haplotype 3 (H3) is the most shared haplotype and distributed in both lakes, and 78.5% of all analyzed individuals were observed. Both trees obtained from phylogenetic analyzes showed that the Muğla populations of Coptodon were included in the C.zillii clade. The results from morphological analysis showed that the Peçenek population differed from the other two populations in terms of most characters. Although there was some overlap among two lake populations, they were largely different from each other. As a result, Kocagöl, Köyceğiz Lake and Peçenek systems were invaded by a single species of C.zillii and a single founder population with a single introduction. The morphological variations observed between populations are largely not genetically based, indicating that this invasive species has a high degree of phenotypic resilience to environmental change in a new environment. The morphological variations observed between populations are largely not genetically based, and showed that this invasive species has a high degree of phenotypic plasticity to environmental change in a new habitat.