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The role of genetic drift in shaping modern human cranial evolution: a test using microevolutionary modeling.

Smith HF - Int J Evol Biol (2011)

Bottom Line: Applying a microevolutionary framework, within- and among-population variance/covariance (V/CV) structure was compared for several functional and developmental modules of the skull across a worldwide sample of modern humans.Degree of intergroup similarity in facial, temporal bone, and mandibular morphology is significantly correlated with geographic distance; however, much of the variance remains unexplained.These findings provide insight into the evolutionary history of modern human cranial variation by identifying signatures of genetic drift, gene flow, and migration and set the stage for inferences regarding selective pressures that early humans encountered since their initial migrations around the world.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy, Arizona College of Osteopathic Medicine, Midwestern University, 19555 North 59th Avenue, Glendale, AZ 85308, USA.

ABSTRACT
The means by which various microevolutionary processes have acted in the past to produce patterns of cranial variation that characterize modern humans is not thoroughly understood. Applying a microevolutionary framework, within- and among-population variance/covariance (V/CV) structure was compared for several functional and developmental modules of the skull across a worldwide sample of modern humans. V/CV patterns in the basicranium, temporal bone, and face are proportional within and among groups, which is consistent with a hypothesis of neutral evolution; however, mandibular morphology deviated from this pattern. Degree of intergroup similarity in facial, temporal bone, and mandibular morphology is significantly correlated with geographic distance; however, much of the variance remains unexplained. These findings provide insight into the evolutionary history of modern human cranial variation by identifying signatures of genetic drift, gene flow, and migration and set the stage for inferences regarding selective pressures that early humans encountered since their initial migrations around the world.

No MeSH data available.


Multidimensional scaling (MDS) plot of Mahalanobis D2 distances among populations based on three-dimensional morphology of the:  (a) basicranium,  (b) temporal bone,  (c) face, and  (d) mandible. All plots use the following color scheme: Africa  =  red; Asia  =  orange; North America  =  green; Europe  =  yellow; Oceania  =  blue.
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fig1: Multidimensional scaling (MDS) plot of Mahalanobis D2 distances among populations based on three-dimensional morphology of the: (a) basicranium, (b) temporal bone, (c) face, and (d) mandible. All plots use the following color scheme: Africa  =  red; Asia  =  orange; North America  =  green; Europe  =  yellow; Oceania  =  blue.

Mentions: The matrices and multidimensional scaling plots of Mahalanobis D2 distances among populations indicated variation in the degree of similarity among groups in the morphology of the various FDMs (Figure 1). In general, most populations grouped roughly according to continent (Figure 1); however, the various continental groups exhibited differing degrees of dispersion and overlap with other groups.


The role of genetic drift in shaping modern human cranial evolution: a test using microevolutionary modeling.

Smith HF - Int J Evol Biol (2011)

Multidimensional scaling (MDS) plot of Mahalanobis D2 distances among populations based on three-dimensional morphology of the:  (a) basicranium,  (b) temporal bone,  (c) face, and  (d) mandible. All plots use the following color scheme: Africa  =  red; Asia  =  orange; North America  =  green; Europe  =  yellow; Oceania  =  blue.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3065169&req=5

fig1: Multidimensional scaling (MDS) plot of Mahalanobis D2 distances among populations based on three-dimensional morphology of the: (a) basicranium, (b) temporal bone, (c) face, and (d) mandible. All plots use the following color scheme: Africa  =  red; Asia  =  orange; North America  =  green; Europe  =  yellow; Oceania  =  blue.
Mentions: The matrices and multidimensional scaling plots of Mahalanobis D2 distances among populations indicated variation in the degree of similarity among groups in the morphology of the various FDMs (Figure 1). In general, most populations grouped roughly according to continent (Figure 1); however, the various continental groups exhibited differing degrees of dispersion and overlap with other groups.

Bottom Line: Applying a microevolutionary framework, within- and among-population variance/covariance (V/CV) structure was compared for several functional and developmental modules of the skull across a worldwide sample of modern humans.Degree of intergroup similarity in facial, temporal bone, and mandibular morphology is significantly correlated with geographic distance; however, much of the variance remains unexplained.These findings provide insight into the evolutionary history of modern human cranial variation by identifying signatures of genetic drift, gene flow, and migration and set the stage for inferences regarding selective pressures that early humans encountered since their initial migrations around the world.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy, Arizona College of Osteopathic Medicine, Midwestern University, 19555 North 59th Avenue, Glendale, AZ 85308, USA.

ABSTRACT
The means by which various microevolutionary processes have acted in the past to produce patterns of cranial variation that characterize modern humans is not thoroughly understood. Applying a microevolutionary framework, within- and among-population variance/covariance (V/CV) structure was compared for several functional and developmental modules of the skull across a worldwide sample of modern humans. V/CV patterns in the basicranium, temporal bone, and face are proportional within and among groups, which is consistent with a hypothesis of neutral evolution; however, mandibular morphology deviated from this pattern. Degree of intergroup similarity in facial, temporal bone, and mandibular morphology is significantly correlated with geographic distance; however, much of the variance remains unexplained. These findings provide insight into the evolutionary history of modern human cranial variation by identifying signatures of genetic drift, gene flow, and migration and set the stage for inferences regarding selective pressures that early humans encountered since their initial migrations around the world.

No MeSH data available.