Table 3
Analysis of Molecular Variance (AMOVA)
among four breeding grounds of Harp Seals (Pagophilus groenlandicus)

    Harp Seals breed in only four areas of the North Atlantic and adjacent waters. In the western Atlantic, these are the Newfoundland / Labrador Ice Front (NL) and the southern Gulf of Saint Lawrence (GS). These two areas are separated by the Strait of Belle Isle at the tip of the Northern Peninsula of Newfoundland, as well as the freshwater outflow of the St. Lawrence River. In the Eastern Atlantic, breeding populations occur at Jan Mayen Island in the Greenland Sea (GS) east of Greenland, and in the White Sea (WS) east of the Kola Peninsula. Over-hunting of the Jan Mayen population in the early 20th century reduced its numbers to a small fraction of its former size. The extent to which gene flow connects the western and eastern pairs, and allows trans-Atlantic exchange, have been long-standing questions.

    An Analysis of Molecular Variance (AMOVA) is similar to a conventional Analysis of Variance (ANOVA), where the variance of interest is DNA sequence variability. Harp Seals lend themselves well to AMOVA, because explicit a priori models of gene flow can be tested and compared. Model I shows that a significant fraction (5.80%, p < 0.05) of the variance occurs among populations, consistent with genetic isolation by distance. Model III, which combines the two western populations and leaves the two eastern populations separate, shows a similar fraction (4.56%) among groups, and 3.55% (p < 0.05) among populations within groups.

Data from Carr et al. (2015); text © 2020 by Steven M Carr