Body size and lean mass of brown bears across and within four diverse ecosystems

Journal of Zoology
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Abstract

Variation in body size across populations of brown bears (Ursus arctos) is largely a function of the availability and quality of nutritional resources while plasticity within populations reflects utilized niche width with implications for population resiliency. We assessed skull size, body length, and lean mass of adult female and male brown bears in four Alaskan study areas that differed in climate, primary food resources, population density, and harvest regime. Full body-frame size, as evidenced by asymptotic skull size and body length, was achieved by 8 to 14 years of age across populations and sexes. Lean body mass of both sexes continued to increase throughout their life. Differences between populations existed for all morphological measures in both sexes, bears in ecosystems with abundant salmon were generally larger. Within all populations, broad variation was seen in body size measures of adults with females displaying roughly a 2-fold difference in lean mass and males showing a 3- to 4-fold difference. The high level of intraspecific variation seen across and within populations suggests the presence of multiple life-history strategies and niche variation relative to resource partitioning, risk tolerance or aversion, and competition. Further, this level of variation indicates broad potential to adapt to changes within a given ecosystem and across the species’ range.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Body size and lean mass of brown bears across and within four diverse ecosystems
Series title Journal of Zoology
DOI 10.1111/jzo.12536
Volume 305
Issue 1
Year Published 2018
Language English
Publisher Wiley
Contributing office(s) Alaska Science Center Biology MFEB
Description 10 p.
First page 53
Last page 62
Country United States
State Alaska