Climatic oscillations during the Pleistocene epoch had a dramatic impact on the distribution of biota in the northern hemisphere. In order to trace glacial refugia and postglacial colonization routes on a global scale, we studied mitochondrial DNA sequence variation in a freshwater fish (burbot, Lota lota; Teleostei, Gadidae) with a circumpolar distribution. The subdivision of burbot in the subspecies Lota lota lota (Eurasia and Alaska) and Lota lota maculosa (North America, south of the Great Slave Lake) was reflected in two distinct mitochondrial lineages (average genetic distance is 2.08%). The lota form was characterized by 30 closely related haplotypes and a large part of its range (from Central Europe to Beringia) was characterized by two widespread ancestral haplotypes, implying that transcontinental exchange/migration was possible for cold-adapted freshwater taxa in recent evolutionary time. However, the derived mitochondrial variants observed in peripheral populations point to a recent separation from the core group and postglacial recolonization from distinct refugia. Beringia served as refuge from where L. l. lota dispersed southward into North America after the last glacial maximum. Genetic variation in the maculosa form consisted of three mitochondrial clades, which were linked to at least three southern refugia in North America. Two mitochondrial clades east of the Continental Divide (Mississippian and Missourian clades) had a distinct geographical distribution in the southern refuge zones but intergraded in the previously glaciated area. The third clade (Pacific) was exclusively found west of the Continental Divide.

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We used closely related haplotypes of the mitochondrial control region of burbot (Lota lota) (Teleostei; Gadidae) with known sequences to assess the sensitivity of a standardized PRS (PCR‐RF‐SSCP) approach. In total, 537 pairwise comparisons between PRS patterns were evaluated. Only seven mutations did not result in a detectable change that resulted in 11 pairwise comparisons (2%) with indistinguishable haplotypes. The haplotypes that could not be discriminated were always characteristic for a certain assemblage (glacial race). As such, this method provides a reliable alternative to direct sequencing for phylogeographic studies in case intrapopulation diversity is limited.

The goal of this study is to evaluate the associated use of the proxies δ 18 O and Mg/Ca, both analyzed in foraminifera tests. δ 18 O and trace metals analyses were performed in order to achieve this purpose on samples of planktonic (G. ruber and G. sacculifer) and benthic (Cibicidoides spp., C. corpulentus, Uvigerina spp. and H. elegans) species of foraminifera from two cores from South Atlantic. Despite of the fact that the proxies used on this study present distinct fits within the species they correlate very well, being possible to estimate the values of temperature, δ 18 O SW and δ 18 O Local. Based on the temperature estimated by Mg/Ca it was possible to identify a negative anomaly of-1,5 ± 0,2 °C between the LGM and HL, meanwhile a positive anomaly of 1,7 ± 0,4 °C was observed in the deep waters for the same period. The δ 18 O SW data estimated by temperature and δ 18 O indicate an oscilation of 1,0 ± 0,1 ‰ and 2,0 ± 0,2 ‰ for planktonic and benthic species between the LGM and the HL. Based on the literature value for the ice volume signal (~1,2 ‰) the superficial waters of the study area indicated a very low salinity oscilation, opposite to the high salinity oscillation in the deep waters. The δ 18 O Local estimatives exhibited a very weak salinity oscillation between LGM and HL in the superficial waters (~0,1 ‰), providing a much more strong oscilation in the deep waters (1,0 ± 0,3 ‰). The salinity increase during the LGM in the deep waters establish the validity of the positive temperature anomaly observed in this study, since the density of the deep water needs to be adequate to maintain the water column stratification.