Canonical and Principal Components of Shape

Darroch, J. N.; Mosimann, James E.

doi:10.2307/2336077

Cited by 157 publications

(202 citation statements)

References 6 publications

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“…Before analysis, size correction was performed by dividing each measurement by the geometric mean of the individual (Darroch and Mosimann, 1985). Missing values were replaced by multiple regression estimations.…”

Section: Methodsmentioning

confidence: 99%

Climate Signatures in the Morphological Differentiation of Worldwide Modern Human Populations

Hübbe

Hanihara

Harvati

2009

The Anatomical Record

184

242

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The ability of cranial morphology to reflect population/phylogenetic history, and the degree to which it might be influenced by environmental factors and selection pressures have been widely discussed. Recent consensus views cranial morphology as largely indicative of population history in humans, with some anatomical cranial regions/measurements being more informative on population history, while others being under selection pressure. We test earlier findings using the largest and most diverse cranial dataset available as yet: 7,423 male specimens from 135 geographic human population samples represented by 33 standard craniometric linear measurements. We calculated Mahalanobis D 2 for three datasets: complete cranial dataset; facial measurement dataset; and neurocranial measurement dataset; these morphological distance matrices were then compared to matrices of geographic distances as well as of several climatic variables. Additionally, we calculated Fst values for our cranial measurements and compared the results to the expected Fst values for neutral genetic loci. Our findings support the hypothesis that cranial, and especially neurocranial morphology, is phylogenetically informative, and that aspects of the face and cranium are subject to selection related to climatic factors. The Fst analysis suggest that selection to climate is largely restricted to groups living in extremely cold environments, including Northeast Asia, North America, and Northern Europe, though each of these regions appears to have arrived at their morphology through distinct adaptive pathways. Anat Rec, 292:1720Rec, 292: -1733Rec, 292: , 2009. Key words: Fst; craniometrics; adaptation; population history; human variation; NeanderthalsThe degree to which human cranial morphology reflects population history or adaptive and developmental changes related to environmental conditions is the subject of ongoing scientific discussion in anthropology. Our understanding of the evolutionary processes affecting morphological variation directly impacts both the study of modern human geographic diversity as well as the interpretation of the human fossil record. The relevance of cranial morphology to phylogenetic reconstruction has been questioned in the past (see e.g., Collard and Wood, 2000), and convergence, parallelism, reversals, and environmen-

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Section: Methodsmentioning

confidence: 99%

Climate Signatures in the Morphological Differentiation of Worldwide Modern Human Populations

Hübbe

Hanihara

Harvati

2009

The Anatomical Record

184

242

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“…This strategy results in a growth difference matrix, which is written GDM(A 2 ,A 1 : B 2 ,B 1 ) [i.e., GM(A 2 ,A 1 )/GM(B 2 ,B 1 )]. To compare shape changes associated with development across differently sized species, samples are size-corrected by the geometric mean (Darroch and Mosimann, 1985;Jungers et al, 1995;Lele and Cole, 1996) of all inter-landmark distances in the mean form matrix.…”

Section: Morphometric Analysis Of Shape and Growth Similaritymentioning

confidence: 99%

Common patterns of facial ontogeny in the hominid lineage

Ackermann

Krovitz²

2002

Anat. Rec.

102

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Recent evaluation of Neanderthal and modern human ontogeny suggests that taxon-specific features arose very early in development in both lineages, with early, possibly prenatal, morphological divergence followed by parallel postnatal developmental patterns. Here we use morphometric techniques to compare hominoid facial growth patterns, and show that this developmental phenomenon is, in fact, not unique to comparisons between Neanderthals and modern humans but extends to Australopithecus africanus and to the hominoid lineage more broadly. This finding suggests that a common pattern of juvenile facial development may be more widespread and that the roots of ontogenetically early developmental differentiation are deep-perhaps predating the ape/human split of 6؉ million years ago.

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“…The geometric mean of a set of linear measurments provides one useful estimate of overall size (Mosimann and James 1979;Darroch and Mosimann 1985). The log geometric mean of p original variables is calculated for each observation as [lln(X;)]/p, where Xi is the value of the ith variable for a given observation.…”

Section: Estimates Of Genetic Variability In Size and Shapementioning

confidence: 99%

Short‐term Evolution in the Size and Shape of Pea Aphids

Via

Shaw

1996

Evolution

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Abstract.-Phenotypic evolution in contemporary populations can generally be witnessed only when novel selective forces produce rapid evolution. Examples of conditions that have led to rapid evolution include drastic environmental change, invasion of a new predator, or a host-range expansion. In cyclical parthenogens, however, yearly cycles of phenotypic evolution may occur due to the loss of adaptation during recombination in the sexual phase (genetic slippage), permitting an opportunity to observe adaptive evolutionary change in contemporary populations that are not necessarily subject to new patterns of natural selection. In insect herbivores, comparative studies suggest that morphological features that aid individuals in remaining on the plant or exploiting it as a food source are likely targets for selection. Here, we estimated the genetic variability of morphological traits in a cyclical parthenogen, the pea aphid (Acyrthosiphon pisum), to determine the potential for their evolution and we tested the hypothesis that size and! or shape evolves by clonal selection during one season of parthenogenetic reproduction. Genetic variation in a set of morphological traits was estimated using laboratory-reared descendents of clones collected from a single alfalfa field in May 1988 and April 1989 (henceforth, the "early" collections). In both years, there was significant clonal heritability early in the season both for overall morphology and for several individual aspects of size and shape. Because the course of short-term evolutionary change in the multivariate phenotype is a function of patterns of genetic covariance among characters, genetic correlations between size and 12 shape variables were also estimated for these early collections. A comparison between the mean phenotype of each early collection and that of a corresponding "late" collection made from the same field seven to eight clonal generations later in the same years revealed qualitatively similar changes in the average multivariate morphological phenotypes between the time periods in both years, although the difference was only significant for the 1989 samples. The pattern of genetic correlations that we estimated early in the 1989 season between overall size and various shape variables suggests that the observed short-term evolutionary changes in shape could have been due to natural selection acting only to increase overall size. We tested this hypothesis by estimating selection on size using a separate data set in which both demographic and morphological variables were measured on individuals reared under field conditions. Highly significant regressions of individual relative fitness on size were found for two major fitness components. Thus, it is likely that the evolutionary change in morphology that we observed is attributable to natural selection, possibly acting primarily through body size. A shift back to smaller size between the late 1988 and early 1989 collections from the same field suggests that either a cost of recombination or opposing selec...

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Canonical and Principal Components of Shape

Cited by 157 publications

References 6 publications

Climate Signatures in the Morphological Differentiation of Worldwide Modern Human Populations

Climate Signatures in the Morphological Differentiation of Worldwide Modern Human Populations

Common patterns of facial ontogeny in the hominid lineage

Short‐term Evolution in the Size and Shape of Pea Aphids

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