Gísli Vikingsson

The main objective of this study was to confirm the level of genetic differentiation observed among samples of fin whale collected at feeding grounds using a new dataset composed of 500 selected individuals genotyped for 15 microsatellite loci and the mtDNA was sequenced. New methods of amplification have been used (especially for the microsatellite loci) to successfully genotyped these selected individuals. Both types of genetic markers employed revealed a lack of genetic differentiation among samples collected and therefore suggest that extensive gene flow might prevail among fin whale population and/or that a recent population expansion of the species occurred. The signal of population expansion detected with the mtDNA might suggest that population of fin whale are not at equilibrium and that further analyses based on this information should be carried out (calculation of potential time of expansion and divergence). However, the comparison of these results to the allozyme data th...

It has been speculated that humpback whales, Megaptera novaeangliae, from the northeastern North Atlantic breed in tropical waters off the coast of West Africa and therefore that they represent a separate breeding population from that which winters in the West Indies. We determined the genotype at six microsatellite loci as well as the sequence of the first 288 nucleotides in the mitochondrial control region of 133 skin biopsies collected from humpback whales in the central North Atlantic (Iceland and Jan Mayen) and the northeastern North Atlantic (Bear Island and the northern coast of Norway). We detected no significant deviations from Hardy-Weinberg proportions nor any differences in genotype frequencies between localities at the nuclear loci. However, the mitochondrial analyses revealed two distinct matrilineal aggregations: the central and the northeastern North Atlantic. Our findings were not compatible with the idea of a separate eastern North Atlantic breeding ground unless one has been established recently. The proposed alternative hypothesis of a common North Atlantic panmictic population (wintering primarily in the West Indies) in which individual whales display maternally directed site-fidelity to specific feeding grounds was supported by re-sightings of two northeastern North Atlantic humpback whales in the West Indies.

The appeal of genetic inference methods to assess population genetic structure and guide management efforts is grounded in the correlation between the genetic similarity and gene flow among populations. Effects of such gene flow are typically genomewide; however, some loci may appear as outliers, displaying above or below average genetic divergence relative to the genomewide level. Above average population, genetic divergence may be due to divergent selection as a result of local adaptation. Consequently, substantial efforts have been directed toward such outlying loci in order to identify traits subject to local adaptation. Here, we report the results of an investigation into the molecular basis of the substantial degree of genetic divergence previously reported at allozyme loci among North Atlantic fin whale (Balaenoptera physalus) populations. We sequenced the exons encoding for the two most divergent allozyme loci (MDH-1 and MPI) and failed to detect any nonsynonymous substituti...

The paper presents results of new statistical analyses of three old fin whale allozyme and carbonic anhydrase datasets previously published in Árnason et al. (1992) Daníelsdóttir et al. (1991b & 1992a). The first dataset is on the genetic variation at 11 variable allozyme loci in 328 fin whales (Balaenoptera physalus) sampled in two North Atlantic areas; i.e. off West Iceland and Spain, a total of: 283 (Iceland 1985, 1986, 1987 and 1988) and 46 (Spain 1985) samples, respectively. The data is based on further analysis of genotypes at 11 allozyme loci: Ada, Ak-1, Gpd, Ldh-A, Mdh-S, Mpi-1, Pep-A, Pgm-1, Pgi and Sod-A. The new statistical programs applied here include FST, Confidence Intervals (CI) of FST, Nm, PCA, MDS, STRUCTURE and graphical illustration of potential “populations” as in Waples and Gaggiotti (2006). There was significant heterogeneity within each sample and overall samples, all due to heterozygote deficiency. Various genetic analyses on the dataset resulted in signific...