The nasopharynx is an important anatomical structure involved in respiration. Its bony boundaries, including the basicranium and upper cervical vertebrae, may be subject to selective pressures and ...constraints related to respiratory function. Here, we investigate phenotypic integration, or covariation, between the face, the basicranial boundaries of the nasopharynx, and the atlas and axis to understand constraints affecting these structures. We collected three‐dimensional coordinate data from a sample of 80 humans and 44 chimpanzees, and used two‐block partial least squares to assess RV (a multivariate generalization of Pearson's r2), rPLS, the covariance ratio, and effect size for integration among structures. We find that integration is significant among some of these structures, and that integration between the basicranial nasopharynx and vertebrae and between the face and vertebrae is likely independent. We also find divergences in the pattern of integration between humans and chimpanzees suggesting greater constraints among the human face and nasopharynx, which we suggest are linked to divergent developmental trajectories in the two taxa. Evolutionary changes in human basicranial anatomy, coupled with human‐like developmental trajectories, may have required that the face grow to compensate any variation in nasopharyngeal structure. However, we were unable to determine whether the nasopharynx or the face is more strongly integrated with the vertebrae, and therefore whether respiration or biomechanical considerations related to positional behavior may be more strongly tied to vertebral evolution. Future work should focus on greater sample sizes, soft tissue structures, and more diverse taxa to further clarify these findings.
Abstract only
Phenotypic integration is a powerful way of understanding morphological evolution. However, it remains unclear how integration itself evolves. I discuss here a variety of factors ...shaping phenotypic integration of the head and neck in a wide range of mammalian taxa.
The head serves as a site for many important functions and is integrated in complex ways. Across mammals (marsupials=231, carnivores=100, primates=473) the facial skeleton is integrated with the basicranium, regardless of the factors influencing the morphology of the skull. Magnitudes of integration (MI) within the basicranium (carnivores=348, primates=1159) are strongly linked to relative brain size and to the height and breadth of the cranial vault, such that taxa with large brain sizes and relatively broad and tall cranial vaults have lower MI. When the brain can grow upwards and outwards, it may not require such tightly matched basicranial anatomy to support it. Facial size also influences MI, such that taxa with large faces tend to have higher MI. The mechanical requirements of supporting a relatively large face may serve to functionally constrain the basicranium. However, the interplay of facial and brain morphology also plays a role in these relationships. The age divergence or appearance of specific taxa may play a small role in MI as well. Although smaller taxa are better able to respond to selection generally, body size does not specifically affect MI.
The head is also tightly integrated with the neck. Patterns and magnitudes of integration in the head and neck in hominoids (
Homo
=120,
Pan
=112,
Hylobates
=92) largely follow those hypothesized based on
Hox
expression patterns in mice. Transitional vertebrae C2 and C7 differ markedly in MI from all others. Locomotor and postural behavior appears to have no influence on these relationships. Instead, aspects of facial anatomy are likely ultimately driving cervical vertebral morphology.
My results support the contention that phenotypic integration patterns match underlying genetic developmental relationships. Strong natural selection favoring particular anatomical features, such as relatively large brains, may alter patterns of phenotypic integration by breaking down existing developmental patterns, especially those that are not tightly constrained. However, cervical vertebrae may be strongly buffered from environmental pressures. The extent to which external environmental influences act during ontogeny on other features, such as the face, has yet to be examined. Knowledge of such interactions will serve as an important complement to studies of phenotypic integration.
Support or Funding Information
This work was funded by the Wenner‐Gren Foundation and New York University.
Objetivo Identificar y caracterizar el virus SARS-CoV-2 en una leona africana (Panthera leo), hembra, de edad avanzada, que presentó por varios meses signos relacionados con enfermedad respiratoria ...atípica.
Métodos Se tomaron muestras de hisopados nasales 23 días después de haber reportado secreción nasal inicial. Se realizó la detección del virus SARS-Cov2 mediante RT-qPCR y posteriormente se caracterizó el genoma completo mediante secuencia Illumina.
Resultados Desde el punto de vista clínico, los resultados encontrados en las muestras de sangre no mostraron cambios evidentes que se pudieran relacionar con el virus o con todos los signos descritos desde el inicio del caso. Para la secuenciación genómica los análisis mostraron una alineación múltiple comparativa entre los tres genomas (muestra Leona, FIP u NC_045512 Wu han) por medio de Mauve, centrado en los genes Spike, E y M (archivo complementario, parte B). Se logró identificar 5 segmentos muy similares entre Leona y NC_045512 (Wuhan).
Conclusiones Es necesario adelantar más investigaciones para estandarizar el diagnóstico de esta patología en los animales. Así mismo, se requieren estudios genómicos en estas especies. Además, se evidenció con la revisión del estado de la cuestión que existen muchos vacíos del conocimiento en la implicación zoonótica de la pandemia y en el conocimiento de este virus en animales domésticos y silvestres, lo que supone un reto importante para las investigaciones de aquí en adelante.
