Mitochondrial genetic variations of an introduced freshwater fish, goldfish Carassius auratus at the frontier between Europe and Asia (western Anatolia, Turkey): proximity to Europe rather than East Asia?

Carassius auratus is one of the most significant ornamental and food fishes of the world that is globally distributed and well known. Although it is known to have existed at least for six decades and expanding its distribution range in Turkish waters, there is a dearth of information on genetic structure and variations of goldfish in Turkey. In this study, four mitochondrial genes (Cytochrome b, cytochrome oxidase II, 12S ribosomal RNA, and 16S ribosomal RNA) were used to infer the genetic variations of goldfish populations sampled from western part of Anatolia, Turkey. Three populations were clustered under three haplotypes for each gene and all haplotypes were special. Cytochrome b was found to have more variable sites and higher genetic diversity than other genes. According to the haplotype networks, goldfish populations in Turkey showed high level of genetic structuring and originated from the common haplotype known in native East Asian populations of the species. Extensive sampling scheme covering whole Anatolia should provide better understanding on the dispersal pattern of the species.

DNA barcoding common non-native freshwater fish species in Turkey: low genetic diversity but high population structuring.

Negative impacts of introduced non-native freshwater species on native species have been increasingly recognized in the world as well as in Turkey. However, there has been relatively little attention on genetic characterization of alien freshwater fishes in their non-native distribution range and virtually no study has been conducted in Turkey despite its crucial importance in invasion biology. The purpose of this study was to elucidate genetic diversity of common non-native freshwater fish species (Carassius auratus, Carassius gibelio, Gambusia holbrooki, Lepomis gibbosus, and Pseudorasbora parva) using mitochondrial Cytochrome c oxidase subunit I (COI) sequences; known as DNA barcodes. Through the whole dataset, seventeen haplotypes (haplotype diversity = 0.8908) were found containing 145 COI sequences. Mean Kimura two-parameter genetic distances were calculated as 0.209 for interspecific distance and 0.009 for intraspecific variation. COI barcode diversity among populations of the same species was found to be low, especially for C. gibelio, G. holbrooki, and L. gibbosus populations which were 0.5%, 0.6%, and 0.3%, respectively. Our results clearly demonstrate the effectiveness of the DNA barcoding approach both for identifications at species level and revealing intraspecific variation among populations, which could be used for effective management measures for invasive species and conservation strategies for indigenous and endemic species.