Individual Variation in the White-Necked Raven

Baumel, J

doi:10.2307/1364920

Cited by 10 publications

(3 citation statements)

References 5 publications

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“…With the few exceptions of reverse sexual size dimorphism, where females are the larger sex ( Reynolds, 1972 ; Hakkarainen et al, 1996 ; Pande and Dahanukar, 2012 ), males are often larger than females and these size differences are more pronounced in cursorial species ( Hoglund, 1989 ). Furthermore, the relative proportions of the skeleton ( Baumel, 1953 ), skeletal muscle and viscera may differ between the sexes ( Hammond et al, 2000 ). Physiological performance traits (e.g.…”

Section: Introductionmentioning

confidence: 99%

Sex differences in gait utilization and energy metabolism during terrestrial locomotion in two varieties of chicken (Gallus gallus domesticus) selected for different body size

et al. 2015

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In leghorn chickens (Gallus gallus domesticus) of standard breed (large) and bantam (small) varieties, artificial selection has led to females being permanently gravid and sexual selection has led to male-biased size dimorphism. Using respirometry, videography and morphological measurements, sex and variety differences in metabolic cost of locomotion, gait utilisation and maximum sustainable speed (Umax) were investigated during treadmill locomotion. Males were capable of greater Umax than females and used a grounded running gait at high speeds, which was only observed in a few bantam females and no standard breed females. Body mass accounted for variation in the incremental increase in metabolic power with speed between the varieties, but not the sexes. For the first time in an avian species, a greater mass-specific incremental cost of locomotion, and minimum measured cost of transport (CoTmin) were found in males than in females. Furthermore, in both varieties, the female CoTmin was lower than predicted from interspecific allometry. Even when compared at equivalent speeds (using Froude number), CoT decreased more rapidly in females than in males. These trends were common to both varieties despite a more upright limb in females than in males in the standard breed, and a lack of dimorphism in posture in the bantam variety. Females may possess compensatory adaptations for metabolic efficiency during gravidity (e.g. in muscle specialization/posture/kinematics). Furthermore, the elevated power at faster speeds in males may be linked to their muscle properties being suited to inter-male aggressive combat.

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Section: Introductionmentioning

confidence: 99%

Sex differences in gait utilization and energy metabolism during terrestrial locomotion in two varieties of chicken (Gallus gallus domesticus) selected for different body size

et al. 2015

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“…Research in junglefowl supports this, as the females suffer no loss of social rank in relation to aerobic performance [57]. One obvious factor that could affect only female birds is the requirement of egg laying, which is associated with altered pelvic anatomy [58]. A larger pelvis is a common female trait that has important consequences for locomotion [59,60].…”

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confidence: 97%

Understanding sex differences in the cost of terrestrial locomotion

et al. 2011

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Little is known regarding the physiological consequences of the behavioural and morphological differences that result from sexual selection in birds. Male and female Svalbard rock ptarmigans (Lagopus muta hyperborea) exhibit distinctive behavioural differences during the breeding season. In particular, males continuously compete for and defend territories in order to breed successfully, placing large demands on their locomotor system. Here, we demonstrate that male birds have improved locomotor performance compared with females, showing both a lower cost of locomotion (CoL) and a higher top speed. We propose that the observed sex differences in locomotor capability may be due to sexual selection for improved male performance. While the mechanisms underlying these energetic differences are unclear, future studies should be wary when pooling male and female data.

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“…Furthermore, female reproductive specialisation may even require specific skeletal proportions [e.g. a wider pelvis (Baumel, 1953;Smith et al, 2002;Cho et al, 2004) or posture, during pregnancy (Franklin and Conner-Kerr, 1998) or gravidity (Rose et al, 2015b)]. Most studies on gait kinematics, however, have been conducted using individuals of only one sex (Reilly, 2000); without comparing sexes (Rubenson et al, 2004;Watson et al, 2011); or using individuals whose sexes were not reported (Gatesy and Biewener, 1991;Abourachid, 2000Abourachid, , 2001Abourachid and Renous, 2000;Griffin et al, 2004;Nudds et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Differential sex-specific walking kinematics in leghorn chickens (Gallus gallus domesticus) selectively bred for different body size

Rose

Codd

Nudds

2016

Journal of Experimental Biology

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The differing limb dynamics and postures of small and large terrestrial animals may be mechanisms for minimising metabolic costs under scale-dependent muscle force, work and power demands; however, empirical evidence for this is lacking. Leghorn chickens (Gallus gallus domesticus) are highly dimorphic: males have greater body mass and relative muscle mass than females, which are permanently gravid and have greater relative intestinal mass. Furthermore, leghorns are selected for standard (large) and bantam (small) varieties and the former are sexually dimorphic in posture, with females having a more upright limb. Here, high-speed videography and morphological measurements were used to examine the walking gaits of leghorn chickens of the two varieties and sexes. Hindlimb skeletal elements were geometrically similar among the bird groups, yet the bird groups did not move with dynamic similarity. In agreement with the interspecific scaling of relative duty factor (DF, the proportion of a stride period with ground contact for any given foot) with body mass, bantams walked with greater DF than standards, and females walked with greater DF than males. Greater DF in females than in males was achieved via varietyspecific kinematic mechanisms, associated with the presence/ absence of postural dimorphism. Females may require greater DF in order to reduce peak muscle forces and minimise power demands associated with lower muscle to reproductive tissue mass ratios and smaller body size. Furthermore, a more upright posture observed in the standard, but not bantam, females, may relate to minimising the work demands of being larger and having proportionally larger reproductive tissue volume. Lower DF in males relative to females may also be a work-minimising strategy and/or due to greater limb inertia (as a result of greater pelvic limb muscle mass) prolonging the swing phase.

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Individual Variation in the White-Necked Raven

Cited by 10 publications

References 5 publications

Sex differences in gait utilization and energy metabolism during terrestrial locomotion in two varieties of chicken (Gallus gallus domesticus) selected for different body size

Sex differences in gait utilization and energy metabolism during terrestrial locomotion in two varieties of chicken (Gallus gallus domesticus) selected for different body size

Understanding sex differences in the cost of terrestrial locomotion

Differential sex-specific walking kinematics in leghorn chickens (Gallus gallus domesticus) selectively bred for different body size

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