Cobitis dalmatina is a species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of ray-finned fish in the true loach family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 (Cobitidae). It is endemic to Croatia

Croatia

Croatia , officially the Republic of Croatia , is a unitary democratic parliamentary republic in Europe at the crossroads of the Mitteleuropa, the Balkans, and the Mediterranean. Its capital and largest city is Zagreb. The country is divided into 20 counties and the city of Zagreb. Croatia covers ...

. This fish was long believed to be part of the widespread Spined Loach

Spined Loach

The Spined Loach is a common freshwater fish in Europe and Asia. It is sometimes known as spotted weather loach, not to be confused with the "typical" weather loaches of the genus Misgurnus...

 (C. taenia).

Cladistic analysis of DNA sequence

DNA sequence

The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...

 data (nDNA RAG-1 and S7 ribosomal protein

Ribosomal protein

A ribosomal protein is any of the proteins that, in conjunction with rRNA, make up the ribosomal subunits involved in the cellular process of translation. A large part of the knowledge about these organic molecules has come from the study of E. coli ribosomes. Most ribosomic proteins have been...

 intron

Intron

An intron is any nucleotide sequence within a gene that is removed by RNA splicing to generate the final mature RNA product of a gene. The term intron refers to both the DNA sequence within a gene, and the corresponding sequence in RNA transcripts. Sequences that are joined together in the final...

 1, and mtDNA cytochrome b

Cytochrome b

Cytochrome b/b6 is the main subunit of transmembrane cytochrome bc1 and b6f complexes. In addition, it commonly refers to a region of mtDNA used for population genetics and phylogenetics.- Function :...

) confirms that it is properly treated as full species. It belongs to a group including C. bilineata

Cobitis bilineata

Cobitis bilineata is a species of ray-finned fish in the Cobitidae family. It is found in Croatia, Italy, Slovenia, and Switzerland.Its natural habitats are intermittent rivers and freshwater marshes. It is not considered threatened by the IUCN....

, C. narentana

Cobitis narentana

Cobitis narentana is a species of ray-finned fish in the true loach family . It is found in Bosnia and Herzegovina and Croatia.. This fish was long believed to be part of the widespread Spined Loach Cobitis narentana is a species of ray-finned fish in the true loach family (Cobitidae). It is found...

and an undescribed species from the Bosnian-Croatian border region. The Adriatic endemics separated from the ancestors of C. bilineata, today widespread immediately south of the Alps

Alps

The Alps is one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east through Italy, Switzerland, Liechtenstein and Germany to France in the west....

, around 6-5.5 million years ago. This was during the Messinian salinity crisis

Messinian salinity crisis

The Messinian Salinity Crisis, also referred to as the Messinian Event, and in its latest stage as the Lago Mare event, was a geological event during which the Mediterranean Sea went into a cycle of partly or nearly complete desiccation throughout the latter part of the Messinian age of the Miocene...

, when darinage basins throughout the Mediterranean region changed their course. C. dalmatina appears to be quite similar to C. narentana as regards the mitochondrial DNA sequence, but the nuclear DNA sequences differ far more. This typically occurs in cases of hybridization between distinct but related species. In the present case, C. narentana would have mated with C. dalmatina males, perhaps during some Pliocene

Pliocene

The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...

 glacial.

Its natural habitat

Habitat

* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...

s is the Cetina River basin

Drainage basin

A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...

. It is threatened by habitat loss.