Evolutionary selection and morphological integration in the vertebral column of modern humans

Abstract

ObjectivesThe main objective is to quantify integration, modularity, and response to selection in the presacral vertebral column of modern humans.Materials and methodsSeventeen linear variables on each presacral vertebra were collected in 108 modern humans producing a total of ~39,000 measurements. Then, we studied patterns and magnitudes of integration at regional, vertebral, and intra‐vertebral levels. Additionally, we calculated the ability of vertebrae to respond to selection by quantifying differences in evolvability, flexibility, and constraint throughout the spine.ResultsThe results indicate that caudal vertebrae are more evolvable than those located more cranially in the presacral vertebral column, following an increasing pattern of evolvability from the cervical to the lumbar region. Additionally, the atlas and fifth lumbar vertebra show the lowest values of integration, while central thoracic vertebrae display the highest magnitudes of integration.DiscussionThese results could be related to three main factors: body plan organization expressed by the Hox genes, the strong developmental constraints that determine the number of mammalian vertebrae, and, finally, the functional requirements of an adaptation to bipedal locomotion in the human lineage.

Morphological integration and modularity in the hyperkinetic feeding system of aquatic‐foraging snakes

“…2018, 2020; Arlegi et al. 2020). Accordingly, it is possible that the evolutionary and functional modules of H15 (Figs.…”

Phenotypic integration in feliform carnivores: Covariation patterns and disparity in hypercarnivores versus generalists

“…2018; Arlegi et al. 2020; Fabre et al. 2020) as well as integration patterns between skull elements (Goswami 2006; Zelditch et al.…”

Assessing thoraco‐pelvic covariation in Homo sapiens and Pan troglodytes: A 3D geometric morphometric approach

“…The vast majority of the research on patterns of integration and covariation in hominoids are focused on the skull (e.g., Ackermann, 2002; Bastir, 2008; Bastir et al, 2005; Bookstein et al, 2003; Bruner, Pereira‐Pedro, & Bastir, 2017; Mitteroecker & Bookstein, 2008; Neaux et al, 2018; Profico et al, 2017; Püschel, Friess, & Manríquez, 2020; Scott et al, 2018; Singh, Harvati, Hublin, & Klingenberg, 2012; Stelzer, Gunz, Neubauer, & Spoor, 2018), but studies investigating integration and covariation within and between elements of the torso are scarce (Arlegi et al, 2020; Grabowski et al, 2011; Huseynov et al, 2017; Lewton, 2012; Middleton, 2015; Torres‐Tamayo et al, 2018; C. V. Ward et al, 2015). Among those, Middleton (2015) quantified and compared for the first time trunk relationships between H. sapiens and Pan collecting linear metrics and 3D coordinates on disarticulated trunk skeletal elements.…”

“…For example, some studies propose that humans and chimpanzees show integration in the subaxial cervical spine (C3–C7) but it is not clear whether the magnitude of this integration is greater in one group compared to the other (Arlegi, Gómez‐Robles, & Gómez‐Olivencia, 2018; Villamil, 2018). Recently, Arlegi, Veschambre‐Couture, and Gómez‐Olivencia (2020) investigated the integration of the vertebral column in H. sapiens and they detected that the thoracic region is more integrated than the cervical and lumbar regions. These authors related this greater magnitude of integration with specific functional requirements of the thoracic region (e.g., respiratory function) that would be independent from the cervical and lumbar regions.…”