List of Figures:
Fig. 1. Example of a piscivorous (64 cm) and a Giant (100 cm standard length) Lake Trout, respectively, from Great Bear Lake (NT).
Fig. 2. Principal Components Analysis of fatty acids of 79 Lake Trout classified as the piscivorous morph from Great Bear Lake, based on the most discriminating 26 fatty acids from SIMPER analysis, explaining together ~89% of the separation among groups. A) Vectors of individual fatty acids contributing to the positioning of piscivorous individuals and the convex hull delimitating group’s position are shown. B) Individual Lake Trout are represented as circle = Group 1, square = Group 2, triangle = Group 3, and diamond = Group 4. To visualize their variation within and among groups, large symbols were used to depict individuals longer than 900 mm fork length, which were identified as the Giant sub-set in this study. Groups were defined by FactoMineR using fatty acids and they are outlined by convex hulls.
Fig. 3. Fork length (mm) at age (years) for four groups of piscivorous Lake Trout sampled from Great Bear Lake in 2002–2015 (Group 1 = squares; Group 2 = circles; Group 3 = triangles; diamond = Group 4). Large symbols depict Giants (FL > 900 mm) within each group. The von Bertalanffy length-age models are depicted as a solid line (without Giants) and a dashed line (with Giants).
Fig. 4. Results of the Bayesian clustering analysis implemented in the program STRUCTURE (B) and the compoplot of percent membership assignment revealed from the DAPC analysis (B) for piscivorous Lake Trout from Great Bear Lake. Shown is the admixture coefficient/percent membership assignment plot where each individual is represented as a vertical line partitioned into colored segments representative of an individual’s fractional membership in any given cluster (K). The most likely number of genetic clusters was two in both the STRUCTURE analysis (based on lnP[D] and the ∆K statistic of Evanno et al. (2005)) and DAPC analysis (based on the lowest BIC score and with 30 PCs retained).
Fig. 5. Canonical Variate Analyses (95% ellipses) and Principal Components Analysis of body shape (a, d), head shape (b, e) and linear measurements (c, f), respectively, of piscivorous Lake Trout represented as: square = Group 1, circle = Group 2, triangle = Group 3, and diamond = Group 4. The first two PCA axes explained 44.3% and 12.3 % of variation for body shape, 35.1% and 30.7 % of variation for head shape, and 39.6 % and 20.9 % for linear measurements (Fig. 6 d, e, f). To visualize their variation within and among groups, individuals longer than 900 mm FL, which are considered the Giant sub-set in this study, are depicted by larger symbols.
Fig. 6. Residuals of mean (± 95%CI) size-standardized upper and lower jaw lengths, head depth and length, and snout-eye length among piscivorous Lake Trout groups. Grouping symbols are as follows: square = Group 1, circle = Group 2, triangle = Group 3, and diamond = Group 4.