A single mitochondrial haplotype and nuclear genetic differentiation in sympatric colour morphs of a riverine cichlid fish.

Some of the diversity of lacustrine cichlid fishes has been ascribed to sympatric divergence, whereas diversification in rivers is generally driven by vicariance and geographic isolation. In the riverine Pseudocrenilabrus philander species complex, several morphologically highly distinct populations are restricted to particular river systems, sinkholes and springs in southern Africa. One of these populations consists of a prevalent yellow morph in sympatry with a less frequent blue morph, and no individuals bear intermediate phenotypes. Genetic variation in microsatellites and AFLP markers was very low in both morphs and one single mtDNA haplotype was fixed in all samples, indicating a very young evolutionary age and small effective population size. Nevertheless, the nuclear markers detected low but significant differentiation between the two morphs. The data suggest recent and perhaps sympatric divergence in the riverine habitat.

Migration rates and genetic structure of two Hungarian ethnic groups in Transylvania, Romania.

Transylvania's ethnic mosaic is composed of Romanians, German Saxons and Hungarians. The ethnic groups of the Hungarian minority that settled in Romania show differences in dialects, customs and religious affiliations. In this study entire mtDNA control region sequences from 360 individuals of Hungarian ethnicity from two populations (the Csángó and the Székely), settled in the historical region of Transylvania in Romania, were generated and analyzed following high quality sequencing standards. Phylogenetic analyses were used for haplogroup determination, quasi-median network analyses were applied for the visualization of character conflicts, and median joining reconstructions were used for depicting haplotype structures. Affiliation of haplotypes to major west Eurasian haplogroups was confirmed using coding region SNPs. Gene flow between the two populations was low and biased towards a higher migration rate from the Csángó to the Székely than vice versa. Phylogeographic analyses revealed effects of genetic isolation within the Csángó population, which is, in its genetic structure, clearly different from the Székely population. The pronounced genetic divergence between the two populations is in sharp contrast to the expectation of high genetic similarity due to the close geographic proximity of their native homelands. The population data will be incorporated in the EMPOP database (http://www.empop.org).