Reversed sexual dimorphism in the leg muscle architecture of the Eurasian sparrowhawk

Reversed sexual dimorphism (RSD) in size is a deep issue in evolutionary biology. RSD in body mass and linear measures is pronounced in diurnal predatory bird species, especially in those that feed on other birds. Size differences between males and females in internal organs or systems, such as the...

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Bibliographic Details
Published in:Anatomical record (Hoboken, N.J. : 2007) N.J. : 2007), 2023-02, Vol.306 (2), p.437-445
Main Authors: Wang, Lin, Liu, Mingjie, Zhang, Zihui
Format: Article
Language:English
Subjects:
Animals
avivores
Birds
Body mass
Developmental biology
Female
Females
fiber length
Hawks - physiology
intersexual differences
Male
Males
Muscle, Skeletal - physiology
Muscles
physiological cross‐sectional area
Prey
Sex Characteristics
Sex differences
Sexual dimorphism
toes' closing muscles
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Summary:Reversed sexual dimorphism (RSD) in size is a deep issue in evolutionary biology. RSD in body mass and linear measures is pronounced in diurnal predatory bird species, especially in those that feed on other birds. Size differences between males and females in internal organs or systems, such as the appendicular musculature, are less well known. In this study, 14 muscles related to toe closure in the Eurasian sparrowhawk (Accipiter nisus), a bird‐eating species, were selected for dissection and architectural measurement. The muscle mass (MM), physiological cross‐sectional area (PCSA), and fiber length (FL) were compared between sexes to detect the possible presence and/or degree of RSD. The results revealed significant RSD in MM and PCSA and suggested a higher force‐generating capacity in females than in males. In females, greater strength in M. tibialis cranialis, M. iliofibularis, and six digital flexors enabled them to capture and carry larger prey, whereas more massive development in M. abductor digiti II and M. abductor digiti IV provided their feet with greater dexterity to improve the effectiveness of grasping larger mobile prey and preventing escape during capture. Fiber length did not show RSD. Generally, males had longer relative and absolute fiber length, indicative of enhanced working range and speed of contraction that was advantageous when hunting small prey. The differences between the sexes in architectural design and the high degree of RSD in MM and PCSA are correlated with the bird‐eating diet and prey size difference of this species.
ISSN:1932-8486
1932-8494
DOI:10.1002/ar.25066