Genetic structure and admixture between the Posavina and Croatian Coldblood in contrast to Lipizzan horse from Croatia

The Posavina and Croatian Coldblood are Croatian autochthonous horse breeds with interwoven breeding histories for which studbooks have only recently been established. The Lipizzan breed has the oldest formalized breeding and no record of recent genetic introgression from other breeds in Croatia. We analyzed the genetic structure, interbreeding, and breed characteristics by genotyping nine dinucleotide microsatellite loci for 53 Posavina, 37 Croatian Coldblood, and 33 Lipizzan horses and showed that differing breeding schemes and histories have had a strong and measurable impact on the population genetic structure within and between the three breeds. A Bayesian clustering method demonstrated that two population clusters best explain the genetic structure. Samples from the pre-defined breeds of the Posavina and Croatian Coldblood were assigned to a separate genetic cluster, while Lipizzan specimens were assigned to another distinct genetic group. Twelve samples of the Posavina/Croatian Coldblood cluster (13%) showed admixed ancestry with Lipizzan horses. A test for heterozygosity excess, allele frequency distribution mode-shift, and M-ratio test were used to detect genetic evidence of recent population bottlenecks, none of which provided evidence for bottlenecks in the Posavina and Croatian Coldblood populations. In contrast, although somewhat ambiguous, evidence suggests a genetic bottleneck in the Lipizzan population in Croatia.

Biogeography of Phormidium autumnale (Oscillatoriales, Cyanobacteria) in western and central Spitsbergen

Filamentous types from the order Oscillatoriales, particularly the species Phor-midium autumnale, have widely diverse morphotypes, which dominate in Arctic aquatic microbial mats and wet soils. We cultivated 25 strains of Ph. autumnale from Svalbard and compared them with available strains from surrounding regions. The comparison of strains, based on 16S rDNA and 16S-23S rDNA intergenic spacer sequences, revealed the similar- ity of strains from Ellesmere Island, the Canadian Arctic and Abisko, Sweden with strains from Svalbard. The rate of colonization of Ph. atumnale from aquatic habitats is relatively high and we suggest geese as a main transmission vector from surrounding lands. Strains of Ph. autumnale were positioned in the phylogenetic tree according to their occurrence in similar habitats. An apparent clustering factor is the duration of availability of water in lakes and long-lasting streams in contrast to rapid and repeated desiccation in soil and on wetted rock in the spray zone of waterfalls. Strains that grow in very cold waters just above the melting point of snow or ice form a distinct genetic group. The strains investigated in this study show morphological similarity in the shape of the trichomes of the studied specimens. Overall, the cell diameter, except for terminal cells, of our strains varied between 3 and 10 μm. Comparison of 16S rDNA sequences of the genus Ph. autumnale with the previ- ously published definition of the species Microcoleus vaginatus revealed the identity of these two species.

An invasive lineage of sculpins, Cottus sp. (Pisces, Teleostei) in the Rhine with new habitat adaptations has originated from hybridization between old phylogeographic groups

Fish abundance surveys in the Rhine system have shown in the past two decades that there is a rapid upriver invasion of a freshwater sculpin of the genus Cottus . These fish are found in habitats that are atypical for the known species Cottus gobio , which is confined to small cold streams within the Rhine drainage. Phylogeographic analysis based on mitochondrial haplotypes and diagnostic single nucleotide polymorphisms indicates that the invasive sculpins are hybrids between two old lineages from the River Scheldt drainage and the River Rhine drainage, although it is morphologically more similar to the Scheldt sculpins. Most importantly, however, the invasive population possesses a unique ecological potential that does not occur in either of the source populations from the Rhine or the Scheldt, which allows the colonization of new habitats that have previously been free of sculpins. Microsatellite analysis shows that the new lineage is genetically intermediate between the old lineages and that it forms a distinct genetic group across its whole expansion range. We conclude that hybridization between long separated groups has lead to the fast emergence of a new, adaptationally distinct sculpin lineage.