Hybridogeneous biotypes in
spined loaches (genus Cobitis) in
Germany with implications for the conservation of such fish complexes
BOHLEN J., P. RÁB, V. ŠLECHTOVÁ, M. RÁBOVÁ, D. RITTERBUSCH & J. FREYHOF
Abstract
A karyotype and allozyme screening of 12 populations of spined loaches (genus Cobitis) from eight river systems in Germany tested the hypothesis that Cobitis taenia is the only species in these river systems. Three populations contained exclusively C. taenia, while in eight populations from the Odra, Elbe, Weser, Issel and Rhine river basins C. taenia was found together with hybridogenous biotypes including genomes of C. taenia and Cobitus elongatoides Bacescu & Maier. In one population from the Danube basin, hybridogenous biotypes including genomes of C. elongatoides and Cobitis tanaitica Bcescu & Maier were identified. Altogether, five different combinations of genomes were found in the hybridogenous biotypes, which included diploid, triploid and tetraploid specimens. Diploid hybridogenous biotypes were found for the first time. Depending on locality, up to three different biotypes were associated with C. taenia. Several hybridogenous males indicate that gynogenesis is not the only mode of reproduction for the polyploid biotypes. Complexes appear to be a common type of population structure in spined loaches. The widespread occurrence of further hybrid complexes in the whole of Central Europe seems likely. Strong locality-dependent differences in the composition of complexes reflect the independent state of each complex. Consequently, conservation legislation and conservation measures need: i) proper identification of species and population composition; and ii) a concept to treat complexes as evolutionary units.
Keywords: Cobitis
elongatoides, Cobitis taenia,
conservation, hybridization, karyotype, polyploidy