Distribution of the walrus.

<p>PAC, ATL, and LAP groups are indicated in light gray, dark grey and mottled gray, respectively. Area of MAR historical specimen sampling for this study is shown in black. Atlantic subpopulations are: (1) Foxe Basin, (2) southern and eastern Hudson Bay, (3) northern Hudson Bay/Hudson Strait/northern Labrador, (4) western Greenland, (5) in the ‘North Water’ (Baffin Bay/northeastern Canadian Arctic, (6) eastern Greenland, (7) Franz Josef Land/Svalbard, and (8) Kara Sea/Barents Sea.</p

Boxplots of (a) %DA and (b) %AA.

<p>Whiskers denote minimum and maximum of the data. Boxes denote the 2^nd and 3^rd quartiles of the data and the squares denote the data mean. For %DA, negative values indicate a left-side asymmetry while positive values indicate a right-side asymmetry.</p

Morphological measurements taken and corresponding definitions.

<p>*After Committee on Marine Mammals (1967), **Wiig and Gjertz (1996) and ***Wiig et al. (2007).</p

Collection sites for walrus specimens providing DNA data.

<p>Black, gray, and white centered shapes denote MAR, PAC, and ATL regions respectively. Circles indicate new data collected in this study, stars indicate data presented previously <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0099569#pone.0099569-Lindqvist1" target="_blank">[2]</a>. Not shown on the map are samples from Laptev Sea, Svalbard and Franz Josef Land of Lindqvist et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0099569#pone.0099569-Lindqvist1" target="_blank">[2]</a>.</p

Cranial, tusk and mandibular measurements collected from walrus crania where possible.

<p>Numbers indicate measures taken as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0099569#pone-0099569-t002" target="_blank">Table 2</a>. Dashed lines indicate measures taken with a measuring tape. Measure 13 is not shown but is a mediolateral equivalent of measure 12. Images modified from Allen <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0099569#pone.0099569-Allen1" target="_blank">[7]</a>.</p

Regional average percent individual directional asymmetry (%DA) and percent individual absolute asymmetry (%AA) in the MAR and ATL specimens.

<p>Regional average percent individual directional asymmetry (%DA) and percent individual absolute asymmetry (%AA) in the MAR and ATL specimens.</p

Median joining network of walrus haplotypes from PAC (dark gray), LAP (light gray), ATL (white) and MAR (black) regions as found in Lindqvist et al. [2] and this study.

<p>In addition, ATL samples from east of Greenland are indicated in blue. Each line segment denotes one sequence difference, except where numbers indicate differences between more divergent sequences. The circle sizes are indicative of haplotype frequencies across the two studies. Small red circles indicate inferred median vectors.</p

Collection sites for walrus specimens providing morphological data.

<p>Black, gray, and white centered circles denote sites of MAR, PAC, and ATL samples respectively. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0099569#pone.0099569.s001" target="_blank">Table S1</a> gives specific sample origins.</p

Mastoid width (a) and mandible width (b) versus age in known age males (black) and females (gray) from ATL.

<p>Mastoid width (a) and mandible width (b) versus age in known age males (black) and females (gray) from ATL.</p

STRUCTURE MYLU infile

Microsatellite data for Myotis lucifugus from Eastern Canada coded as an infile for the program STRUCTURE