Climatic adaptation vs. neutral evolution: what clues from craniofacial form in native Northern Asiatics?тезисы доклада

Дата последнего поиска статьи во внешних источниках: 29 мая 2015 г.

Работа с тезисами доклада


[1] Climatic adaptation vs. neutral evolution: what clues from craniofacial form in native northern asiatics? / A. Evteev, A. Cardini, I. Morozova, P. O’Higgins // Abstracts. European Society for the study of Human Evolution meeting.Bordeaux, September 2012. — Bordeaux, 2012. — P. 76–76. Most studies concerned with facial adaptations to climate have sampled widely the global population (Thompson, Buxton, 1923; Carey, Steegmann, 1987; Franciscus, 1995; Noback et al., 2011). As such it is difficult to assess the causes of differences; adaptation or genetic drift, since the study groups not only live in different climates but may also have been isolated to some degree for tens of thousands of years. An alternative approach has been to compare different samples of the same ethnic group dispersed through different habitats (Wolpoff, 1968; Shea, 1977; Hernandez, 1997). Such samples are closely genetically related so the differences are more likely adaptive. However, the extent to which findings apply more widely is unclear. Indeed, while differences between tropical and non-tropical groups are well-established (Hubbe et al., 2009), how extreme cold impacts on facial form remains controversial. We present a study that aims to combine those two approaches. Thus, we compared samples of 7 native Siberian, Central and North-East Asian peoples: Evenks, Eastern Buryats, Yakuts, Siberian Inuits, Ulch, Khanty and Mongols, with Northern Chinese and Koreans representing a temperate climatic zone. No tropical populations were included in the analysis. All represent the same general (Mongoloid) craniofacial pattern, live in neighbouring regions and are related in terms of origin and genetics. 37 linear measurements (including several on nasal bones, the piriform aperture, maxilla, choanae and the internal nasal cavity) were taken by the same person on 139 adult male skulls. The set of measurements was designed to take into account both developmental and functional sub-divisions of the mid facial skeleton. . Winter and summer -average annual temperature, vapour pressure and precipitation were used as environmental covariates. The genetic background was estimated from a matrix of pair-wise between-group distances based on frequencies of the 20 main Eurasian mtDNA haplogroups. A two-block partial least squares (PLS) analysis showed highly significant covariation between craniofacial form and climate. Northern groups, compared to populations from temperate climates, shared a very specific craniofacial pattern characterized by: a decrease in nasal bone breadth, an increase in maxillary size as well as in the height of the nasal aperture (without reduction in breadth), and a concomitant lengthening and narrowing of the nasal cavity. This pattern was largely independent of genetic ancestry, more pronounced in Yakuts and Evenks, whose distribution range is further inland, and related to the very cold and dry winter conditions of those regions. Siberian Inuits, Khanty and Ulch, who also live in the north but occupy coastal areas and do not share a most recent common ancestor, had a somewhat modified version of the craniofacial traits observed in Yakuts and Evenks with a substantial narrowing of the nasal aperture, anterior part of the maxilla and the nasal cavity. Since genetic relatedness does not explain the morphological-environmental correlates we have found, differences and similarities in traits most likely represent adaptations to cold/dry versus cold/wet climates.

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