Control of the Cranio-Cervical System During Feeding in Birds

Leeuw, Angélique H. J. Van Der; Bout, Ron G.; Zweers, G. A.

doi:10.1093/icb/41.6.1352

Cited by 21 publications

(45 citation statements)

References 24 publications

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“…However, electromyographic analyses (e.g. van der Leeuw et al, 2001;Herrel et al, 2008;Konow et al, 2011) seem required to fully unravel the role of the neck muscles during tooth-digging. Because of the complexity of the cervical system, the role of each of the fourteen neck muscles during tooth-digging remains unclear (Bekele, 1983b).…”

Section: Discussionmentioning

confidence: 99%

Kinematics of chisel-tooth digging by African mole-rats

Wassenbergh

Heindryckx

Adriaens

2017

Journal of Experimental Biology

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Mole-rats are known to use their protruding, chisel-like incisors to dig underground networks of tunnels, but it remains unknown how these incisors are used to break and displace the soil. Theoretically, different excavation strategies can be used. Mole-rats could either use their head depressor muscles to power scooping motions of the upper incisors (by nose-down head rotations) or the lower incisors (by nose-up head rotations), or their jaw adductors to grab and break the soil after penetrating both sets of incisors into the ground, or a combination of these mechanisms. To identify how chisel-tooth digging works, a kinematic analysis of this behaviour was performed based on high-speed videos of 19 individuals from the African mole-rat species placed inside transparent tubes in a laboratory setting. Our analysis showed that the soil is penetrated by both the upper and lower incisors at a relatively high gape angle, generally with the head rotated nose-up. Initially, the upper incisors remain approximately stationary to function as an anchor to allow an upward movement of the lower incisors to grab the soil. Next, a quick, nose-down rotation of the head further detaches the soil and drops the soil below the head. Consequently, both jaw adduction and head depression are jointly used to power tooth-digging in The same mechanism, but with longer digging cycles, and soil being thrown down at smaller gape sizes, was used when digging in harder soil.

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Section: Discussionmentioning

confidence: 99%

Kinematics of chisel-tooth digging by African mole-rats

Wassenbergh

Heindryckx

Adriaens

2017

Journal of Experimental Biology

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“…ation in the number of neck vertebrae found across other extant and extinct tetrapod lineages (Müller et al 2010). For example, evolutionary variation in avian neck length occurs locally by the addition of cervical vertebrae (Van Der Leeuw 1991;Van Der Leeuw et al 2001). In birds, there seem to be no developmental constraints that fix their number (i.e., variation in vertebral number is rarely accompanied by malformation or cancer) (Fox 1912;Effron et al 1977;Adelman et al 1988; Barja et al 1994;Perez-Campo et al 1998;Galis 1999).…”

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confidence: 99%

Differential scaling patterns of vertebrae and the evolution of neck length in mammals

2017

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Almost all mammals have seven vertebrae in their cervical spines. This consistency represents one of the most prominent examples of morphological stasis in vertebrae evolution. Hence, the requirements associated with evolutionary modifications of neck length have to be met with a fixed number of vertebrae. It has not been clear whether body size influences the overall length of the cervical spine and its inner organization (i.e., if the mammalian neck is subject to allometry). Here, we provide the first large-scale analysis of the scaling patterns of the cervical spine and its constituting cervical vertebrae. Our findings reveal that the opposite allometric scaling of C1 and C2-C7 accommodate the increase of neck bending moment with body size. The internal organization of the neck skeleton exhibits surprisingly uniformity in the vast majority of mammals. Deviations from this general pattern only occur under extreme loading regimes associated with particular functional and allometric demands. Our results indicate that the main source of variation in the mammalian neck stems from the disparity of overall cervical spine length. The mammalian neck reveals how evolutionary disparity manifests itself in a structure that is otherwise highly restricted by meristic constraints.

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“…In a second experiment, we explored the expression profile of these same androgen biosynthesis genes in the downy woodpecker neck muscle, the LC [39]. This tissue actuates the birds drum display, which is functionally similar to birdsong but produced through hammering the bill against a tree (and not via the SYR).…”

Section: Resultsmentioning

confidence: 99%

Skeletal muscles that actuate sexual displays are specialized forde novoandrogen synthesis

Schuppe

Goller

Fuxjager

2019

Preprint

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1The gonads (testes) act as the primary organ where androgenic hormones are 2 made to regulate reproductive behavior in male vertebrates. Yet many endocrinologists 3 have also long suspected that other tissues in the body can autonomously synthesize their 4 own androgens to support behavioral output. We examine this idea here by studying 5 whether avian skeletal muscles that actuate elaborate socio-sexual displays are 6 specialized to maintain the molecular machinery otherwise needed for de novo androgen 7 synthesis. Our results show that the vocal organ, or syrinx (SYR), of two songbirds 8 species does in fact express all transporters and enzymes necessary to create androgenic 9 hormones from scratch. This includes genes that encode proteins to mediate rate-limiting 1 0 steps of steroidogenesis, which are seldom found outside of the gonads. We also show 1 1 that expression levels of these genes are far greater in the SYR than non-display muscles,

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Control of the Cranio-Cervical System During Feeding in Birds

Cited by 21 publications

References 24 publications

Kinematics of chisel-tooth digging by African mole-rats

Kinematics of chisel-tooth digging by African mole-rats

Differential scaling patterns of vertebrae and the evolution of neck length in mammals

Skeletal muscles that actuate sexual displays are specialized forde novoandrogen synthesis

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