Comparative anatomy of the felid brachial plexus reflects differing hunting strategies between Pantherinae (snow leopard, Panthera uncia) and Felinae (domestic cat, Felis catus)

PLOS ONE RESEARCH ARTICLE Comparative anatomy of the felid brachial plexus reflects differing hunting strategies between Pantherinae (snow leopard, Panthera uncia) and Felinae (domestic cat, Felis catus) Margaret I. Hall1,2,3, Tyler Lindvall2, Ana Suarez-Venot2, Dominik Valdez1, Heather F. Smith ID1,2,3,4* a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 1 Department of Anatomy, College of Graduate Studies, Midwestern University, Glendale, Arizona, United States of America, 2 Arizona College of Osteopathic Medicine, Midwestern University, Glendale, Arizona, United States of America, 3 College of Veterinary Medicine, Midwestern University, Glendale, Arizona, United States of America, 4 School of Human Evolution and Social Change, Arizona State University, Tempe, Arizona, United States of America * Abstract OPEN ACCESS Citation: Hall MI, Lindvall T, Suarez-Venot A, Valdez D, Smith HF (2023) Comparative anatomy of the felid brachial plexus reflects differing hunting strategies between Pantherinae (snow leopard, Panthera uncia) and Felinae (domestic cat, Felis catus). PLoS ONE 18(8): e0289660. https://doi. org/10.1371/journal.pone.0289660 Editor: Priti Chaudhary, AIIMS: All India Institute of Medical Sciences, INDIA Received: March 2, 2023 Accepted: July 21, 2023 Published: August 9, 2023 Copyright: © 2023 Hall et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: The data that support the findings of this study are openly available in the body of the paper. The brachial plexus, a network of ventral rami providing somatic sensory and motor innervation to the forelimb, is of particular importance in felids. Large-bodied pantherines require powerful rotatory and joint stabilizing forelimb muscles to maintain secure holds on large prey, while smaller-bodied felines are small prey specialists reliant on manual dexterity. Brachial plexus dissections of two snow leopards (Panthera uncia) and two domestic cats (Felis catus) revealed that generally the morphology of the brachial plexus is quite conserved. However, differences in the nerves supplying the shoulder and antebrachium may reflect differing prey capture strategies between the subfamilies. The brachial plexus of both species derives from ventral rami of C6-T1. In P. uncia, an extensive musculus (m.) subscapularis with multiple pennations is innervated by a larger number of nn. subscapulares, deriving from more spinal cord levels than in F. catus. C6 continues to become n. suprascapularis in both taxa; however, in F. catus, it also gives branches that join with C7, while in P. uncia, it is dedicated to musculi (mm.) supraspinatus, infraspinatus, and a small branch to cervical musculature. In F. catus, nervus (n.) medianus receives direct contributions from more ventral rami than P. uncia, possibly reflecting a greater reliance on manual dexterity in prey capture in the former. In addition to primary innervation by n. thoracodorsalis, m. latissimus dorsi is also innervated by n. thoracicus lateralis near the axilla in both taxa, suggesting that it may belong to a complex of proximal forelimb musculature along with mm. pectoralis profundus and cutaneus trunci. Funding: This work was funded by Midwestern University faculty intramural funds and an AZCOM Kenneth A. Suarez Summer Research Fellowship to Ana Suarez-Venot. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. PLOS ONE | https://doi.org/10.1371/journal.pone.0289660 August 9, 2023 1 / 12 PLOS ONE Competing interests: The authors have declared that no competing interests exist. Snow leopard brachial plexus Introduction Carnivoran species can generally be classified as falling into one of two dietary specialization groups, largely determined by body mass [1–3]. Among felids, taxa with body masses of >25 kg will typically focus on hunting large prey, as that hunting strategy is most energy efficient [3]. Most large-bodied felids in this size class belong to the subfamily Pantherinae and have the capability of killing prey more than double their own body mass. Felid species <15 kg hunt exclusively small prey [3]. These species belong to the subfamily Felinae, and primarily hunt prey significantly smaller than themselves. Felids in the intermediate range, 15–25 kg, are variable in hunting strategy. The snow leopard (Panthera uncia) and domestic cat (Felis catus) exemplify the two different prey capture strategies between the two felid subfamilies, the Pantherinae and Felinae. Panthera uncia hunts a wide array of taxa from small rodents to large Siberian ibex (Capra sibirica) [4]. As a solitary hunter it relies on overhead ambush and powerful grasping to immobilize large prey [5]. In contrast, felines such as F. catus primarily hunt small rodents and birds and typically focus on manual acquisition of prey [2, 6]. Fundamental adaptive differences exist in the forelimb myological patterns in pantherines compared to felines, which reflect their different prey capture strategies [3, 6–8]. To sustain a secure hold while grappling with large prey, pantherines typically require robust joint shoulder musculature and powerful joint-stabilizing forelimb muscles [6, 9]. This pattern holds true in P. uncia, which displays forelimb musculature suited to hunting behavior intermediate to scansorial and cursorial species, which is required for restraining large prey while remaining flexible enough to climb uneven surfaces [9]. In contrast, as small prey specialists, many felines possess robust digital flexor and extensor muscles, which facilitate manual dexterity [6]. Highly cursorial carnivorans typically have a proportionately larger proximal muscle mass in the forelimb, while those that rely on manual dexterity possess comparatively larger distal forelimb musculature [10, 11]. While previous studies have revealed significant adaptive muscular differences in the forelimbs between pantherines and felines, the neurological mechanisms supporting these differences are still poorly understood. While the brachial plexus has recently been studied in a variety of feline species, including Leopardus geoffroyi [12], Leopardus pardalis [13], Puma concolor [14], Puma yagouaroundi [15], and the Van cat (a breed of Felis catus) [16], it remains largely unexplored among Pantherinae. This study investigates the morphology of the brachial plexus in representative pantherine and feline species to identify adaptive peripheral nerve differences between these small and large prey specialists. Materials and methods The sample consisted of one pantherine species, P. uncia, and one feline species, F. catus. The two P. uncia specimens included a 22-year-old male (studbook number 2012) and 16-year-old (...truncated)