Larger body size leads to greater female beluga whale ovarian reproductive activity at the southern periphery of their range ...

• Main Authors: Ferguson, Steven, Yurkowski, David, Hudson, Justine, Edkins, Tera, Willing, Cornelia, Watt, Cortney
• Format: Dataset
• Language: English
• Published: Dryad 2021
• Subjects: FOS Biological sciences; Arctic; Baffin Bay; Baffin; Beluga; Beluga whale; Beluga*; Delphinapterus leucas; Hudson Bay
• Online Access: https://dx.doi.org/10.5061/dryad.hmgqnk9j3; https://datadryad.org/stash/dataset/doi:10.5061/dryad.hmgqnk9j3

Identification of phenotypic characteristics in reproductively successful individuals provides important insights into the evolutionary processes that cause range shifts due to environmental change. Female beluga whales (Delphinapterus leucas) from the Baffin Bay region (BB) of the Canadian Arctic in the core area of the species’ geographic range have larger body size than their conspecifics at the southern range periphery in Hudson Bay (HB). We investigated the mechanism for this north and south divergence as it relates to ovarian reproductive activity (ORA = total corpora) that combines morphometric data with ovarian corpora counted from female reproductive tracts. Our study aim was to assess the relative influence of age and body size of female beluga whale on ovarian reproductive activity in the two populations. Female beluga whale ORA increased more quickly with age (63% partial variation explained) in BB than in HB (41%). In contrast, body length in HB female beluga whales accounted for considerably ... : The dataset included 172 female reproductive tracts with at least one corpus: 41 from BB and 131 from HB. To create a complete dataset required for robust statistical testing (Moritz & Bartz-Beielstein 2017), missing length and age data were replaced with the median value of all whales in each population. The five BB whales with missing age were assigned 20 years-of-age and the 6 HB whales, 26 years-of-age. Similarly, the 6 BB whales with missing length were assigned 354 cm and the 17 HB whales with missing length, 327 cm. We conducted post-mortem gross examinations of female reproductive tracts, collected from 17 northern communities within the Eastern Canadian Arctic from 1989 to 2014 (Fig. 1). Ageing was based on examination of dentine and cementum growth layer groups in teeth (Waugh et al. 2018). Whale standard length was measured in the field according to a standard protocol, measured from the middle of the fluke to the tip of the rostrum (American Society of Mammalogists, 1961). We combined ...