DescriptionDetecting weak population structure based on estimates of allele/haplotype frequency divergence alone depends on the degree of divergence, statistical power and genetic markers, but holds low power at “ecological” dispersal rates. Kinship-based methods, on the other hand, are better suited at “ecological” rates and complementing traditional population genetic approaches. We combined conventional F-statistics and coalescence methods with kinship-based approaches to assess the population structure of the North Atlantic (NA) and Mediterranean Sea (MED) fin whales (Balaenoptera physalus). An analysis based upon 20 microsatellite loci and 450 base pair mitochondrial DNA control region sequences from ~1,600 individuals identified a break in gene flow between the NA and MED (F_ST = 0.005, P < 0.001 and F_ST = 0.17, P < 0.001 for nuclear and mitochondrial markers, respectively), connected by asymmetric gene flow. Among NA sampling areas, a low degree of isolation-by-distance was detected between the western and eastern NA at both nuclear (r = 0.30, P = 0.018) and mitochondrial (r = 0.32, P = 0.016) markers. Average pairwise relatedness among individuals was higher within compared to between regions (t = -10.62, d.f. = 911.83, P < 0.001). We identified 140 parent-offspring dyads among which were 125 dyads with both individuals sampled in the same area and 15 dyads where members sampled in different areas, ranging up to 3,300 km apart. In the western NA, evidence of weak, fine-scale structuring was detected between the Gulf of Maine and Gulf of St. Lawrence. The high within-area relatedness coupled with substantial connectivity among areas suggests that fin whale migratory behaviour differs from species with well-characterised seasonal migratory patterns, such as humpback whales (Megaptera novaeangliae). While fin whales have the capacity of wide-ranging movements, the low heterogeneity among areas was consistent with maternally-directed site-fidelity and short-range seasonal movements.
|Period||9-Dec-2019 → 12-Dec-2019|
|Event title||World Marine Mammal Conference: null|
|Degree of Recognition||International|