Home  About us  Contact
 

Molecular Distances (molecular + distance)

Distribution by Scientific Domains
Life Sciences100%

Selected Abstracts

Genetic, geographic, and environmental correlates of human temporal bone variation

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2007
Heather F. Smith
Abstract Temporal bone shape has been shown to reflect molecular phylogenetic relationships among hominoids and offers significant morphological detail for distinguishing taxa. Although it is generally accepted that temporal bone shape, like other aspects of morphology, has an underlying genetic component, the relative influence of genetic and environmental factors is unclear. To determine the impact of genetic differentiation and environmental variation on temporal bone morphology, we used three-dimensional geometric morphometric techniques to evaluate temporal bone variation in 11 modern human populations. Population differences were investigated by discriminant function analysis, and the strength of the relationships between morphology, neutral molecular distance, geographic distribution, and environmental variables were assessed by matrix correlation comparisons. Significant differences were found in temporal bone shape among all populations, and classification rates using cross-validation were relatively high. Comparisons of morphological distances to molecular distances based on short tandem repeats (STRs) revealed a significant correlation between temporal bone shape and neutral molecular distance among Old World populations, but not when Native Americans were included. Further analyses suggested a similar pattern for morphological variation and geographic distribution. No significant correlations were found between temporal bone shape and environmental variables: temperature, annual rainfall, latitude, or altitude. Significant correlations were found between temporal bone size and both temperature and latitude, presumably reflecting Bergmann's rule. Thus, temporal bone morphology appears to partially follow an isolation by distance model of evolution among human populations, although levels of correlation show that a substantial component of variation is unexplained by factors considered here. Am J Phys Anthropol 2007. © 2007 Wiley-Liss, Inc. [source]

Which cranial regions reflect molecular distances reliably in humans?

AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 1 2009
Evidence from three-dimensional morphology
Knowledge of the degree to which various subsets of morphological data reflect molecular relationships is crucial for studies attempting to estimate genetic relationships from patterns of morphological variation. This study assessed the phylogenetic utility of six different human cranial regions, plus the entire cranium. Three-dimensional landmark data were collected for 83 landmarks from samples of skulls from 14 modern human populations. The data were subsequently divided into anatomical regions: basicranium, upper face, mandible, temporal bone, upper jaw, cranial vault, and a subset of points from around the entire cranium. Depictions of population molecular distances were calculated using published data on microsatellites for the same or closely related populations. Distances based on morphological variation of each of the anatomical regions were compared with molecular distances, and the correlations assessed. The morphology of the basicranium, temporal bone, upper face, and entire cranium demonstrated the highest correlations with molecular distances. The morphology of the mandible, upper jaw, and cranial vault, as measured here, were not significantly correlated with molecular distances. As the three-dimensional morphology of the temporal bone, upper face, basicranium, and entire cranium appear to consistently reflect genetic relationships in humans, especially with more reliability than the cranial vault, it would be preferable to focus on these regions when attempting to determine the genetic relationships of human specimens with no molecular data. Am. J.Hum. Biol., 2009. © 2008 Wiley-Liss, Inc. [source]

Genetic, geographic, and environmental correlates of human temporal bone variation

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2007
Heather F. Smith
Abstract Temporal bone shape has been shown to reflect molecular phylogenetic relationships among hominoids and offers significant morphological detail for distinguishing taxa. Although it is generally accepted that temporal bone shape, like other aspects of morphology, has an underlying genetic component, the relative influence of genetic and environmental factors is unclear. To determine the impact of genetic differentiation and environmental variation on temporal bone morphology, we used three-dimensional geometric morphometric techniques to evaluate temporal bone variation in 11 modern human populations. Population differences were investigated by discriminant function analysis, and the strength of the relationships between morphology, neutral molecular distance, geographic distribution, and environmental variables were assessed by matrix correlation comparisons. Significant differences were found in temporal bone shape among all populations, and classification rates using cross-validation were relatively high. Comparisons of morphological distances to molecular distances based on short tandem repeats (STRs) revealed a significant correlation between temporal bone shape and neutral molecular distance among Old World populations, but not when Native Americans were included. Further analyses suggested a similar pattern for morphological variation and geographic distribution. No significant correlations were found between temporal bone shape and environmental variables: temperature, annual rainfall, latitude, or altitude. Significant correlations were found between temporal bone size and both temperature and latitude, presumably reflecting Bergmann's rule. Thus, temporal bone morphology appears to partially follow an isolation by distance model of evolution among human populations, although levels of correlation show that a substantial component of variation is unexplained by factors considered here. Am J Phys Anthropol 2007. © 2007 Wiley-Liss, Inc. [source]