The author measured 111 specimens (61 male, 50 female) of the Japanese red fox (Vulpes vulpes japonica) collected by the Tochigi Prefectural Museum during 1981–1991 and by the author during 1986–1994. Analyses of 16 parameters of external morphology of the specimens revealed sexual dimorphisms in linear parameters: total length, head and body length (HBL), and hind foot length (HFL) were significantly greater in males (5–6%: P < 0.001). Furthermore, analyses of these parameters using an allometric formula showed that the relative growth of HFL to HBL and shoulder height to HBL stops earlier in males than in females. The male/female ratios were large for body weight, body length, and parameters related to circumference, but they were mostly not significant because they are influenced by seasonal changes and body conditions that are influenced mainly by fat deposition. Greater thickness gives the visual impression of largeness, providing advantages for males to be selected by females. Consequently, greater thickness might have caused, at least partially, male-bias size dimorphism. Moreover, sexual difference in relative growth might be some adaptive advantage of locomotive behavior in males. Early investment in locomotive capability in males might engender acquirement of females and consequently, mating success.
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1 June 2010
Sexual Dimorphism and Relative Growth of Body Size in the Japanese Red Fox Vulpes vulpes japonica
Masahiko Takeuchi
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Mammal Study
Vol. 35 • No. 2
June 2010
Vol. 35 • No. 2
June 2010
allometry
body size
relative growth
sexual difference
Vulpes vulpes