Characterizing the admixed African ancestry of African Americans

Background

Accurate, high-throughput genotyping allows the fine characterization of genetic ancestry. Here we applied recently developed statistical and computational techniques to the question of African ancestry in African Americans by using data on more than 450,000 single-nucleotide polymorphisms (SNPs) genotyped in 94 Africans of diverse geographic origins included in the HGDP, as well as 136 African Americans and 38 European Americans participating in the Atherosclerotic Disease Vascular Function and Genetic Epidemiology (ADVANCE) study. To focus on African ancestry, we reduced the data to include only those genotypes in each African American determined statistically to be African in origin.

Results

From cluster analysis, we found that all the African Americans are admixed in their African components of ancestry, with the majority contributions being from West and West-Central Africa, and only modest variation in these African-ancestry proportions among individuals. Furthermore, by principal components analysis, we found little evidence of genetic structure within the African component of ancestry in African Americans.

Conclusions

These results are consistent with historic mating patterns among African Americans that are largely uncorrelated to African ancestral origins, and they cast doubt on the general utility of mtDNA or Y-chromosome markers alone to delineate the full African ancestry of African Americans. Our results also indicate that the genetic architecture of African Americans is distinct from that of Africans, and that the greatest source of potential genetic stratification bias in case-control studies of African Americans derives from the proportion of European ancestry.     

Conserving the African rhinoceros

The Southern African rhinoceros population has been dwindling through the years. A lot of effort has been put toward coming up with the most effective way of protecting the black and white rhinoceros population in the world yet still the animals remain endangered despite the enormous global efforts to protect the species. Such conservation efforts include; establishment of sanctuaries, wildlife farming, dehorning, trade and market controls, listing of species as endangered, use of biotechnology and biotelemetry. However useful, each of these methods has its own strengths and weaknesses relative to the success of rhinoceros conservation. It however has been noted in this review that dehorning is the most effective method as it involves removal of the horn hence extinguishing the need for poaching. Despite the high success rate it has also been noted that this requires a great deal of skill and finance hence limiting the application of this technique in developing nations. Sanctuaries provide an ideal breeding environment that is better than the wild and enhanced breeding accounted for a significant increase in rhinoceros population where it has been applied. It was however been conclude that a holistic conservation approach is required to conserve the African rhinoceros.     

Classification of the southern African sanga and East African shorthorned zebu

Humped African cattle, which are differentiated into zebu and sanga types, have traditionally been classified as Bos indicus . This paper discusses existing evidence and presents new evidence supporting the classification of southern African sangas as Bos taurus and East African zebus as ' taurindicus '. Classification is based on karyotype, frequencies of DNA markers and protein polymorphisms. The Boran, an East African zebu, has an acrocentric Y chromosome typical of Bos indicus . The southern African sanga breeds have a submetacentric Y chromosome typical of Bos taurus . Frequencies of four DNA markers support the hypothesis that the Tuli, a southern African sanga, had taurine ancestors and the Boran had both taurine and indicine ancestors. Frequencies for several protein polymorphisms strongly suggest that southern African sangas have more in common with taurine than with indicine breeds, while East African zebus are an admixture of African taurine and Asian indicine breeds.     

Distribution and abundance of African waterfowl: examples from the African Waterfowl Census

Dodman, T. & Rose, P. 2000. Distribution and abundance of African waterfowl: examples from the African Waterfowl Census. Ostrich 71 (1 & 2): 235–243.

Wetlands International coordinates waterfowl counts in Africa. Counts from 1958–1990 were analysed in 1991, when the African Waterfowl Census (AfWC) was also launched. By 1996, 25 countries were participating. This preliminary appraisal of the AfWC shows that resulting data can be used to identify distribution and abundance patterns, although there are still significant gaps in AfWC coverage and focus. The degree to which AfwC data may be used to assess the conservation status of African waterfowl populations depends on a function of data quality, quantity and reliability. To enable this practical use of data, several priorities for future work are identified, based on the strengths and weaknesses of the current information: (1) simultaneous co-ordinated counts, (2) regular annual or biannual monitoring of the same sites, (3) development of priority list of sites for regular survey, (4) frequent monitoring of particularly important sites (e.g. every three months), (5) building waterbird surveys into broader programmes of ecological monitoring, (6) planning of special internationally coordinated surveys, (7) planning regular complete surveys in major wetlands, e.g. every five years, and (8) extending the AfWC to other taxa and broader surveys of wetland use by man. In Africa, 522 discrete waterbird populations have been identified. Over half the populations for which trends have been established are in decline. Results from a recent atlas of Anatidae are illustrated by the Fulvous Whistling-Duck Dendrocygnu bicolor, for which three discrete populations and 21 key sites are identified. Wetlands are the most important habitats for waterbirds. Many species (e.g. Grey Heron Ardea cinema) exploit a variety of wetland types and are geographically widespread; those with special habitat requirements (e.g. Blue-winged Goose Cyanochen cyanopterus) oh have restricted ranges. Hartlaub's Duck Pteronetta hartlaubi is one of the few waterbirds specific to the tropical forest biome. The movements of Abdim's Stork Ciconia abdimii in southern Africa show a clear response to rainfall.     

African and European perception of African female attractiveness

Majority of research on attractiveness is restricted to faces of European origin. The perception of attractiveness may, however, vary across communities due to variations in both facial morphology and local standards of beauty. We investigated the relative contribution of four facial markers of attractiveness based on 101 female facial portraits (standardized, non-manipulated) from Cameroon and Namibia, which were assessed by local male raters and by raters from a distant European population, the Czech Republic. Images from Cameroon include only women of Bantu origin, while Namibians are represented by women of both Bantu (Owambo/Herero) and Nama origin. While controlling for age and BMI, we explored the relationship between female attractiveness and a set of facial traits: fluctuating asymmetry, averageness, shape sexual dimorphism, and skin color (rated and measured in CIELab color space).In the Cameroonian sample, local male raters favored lighter-skinned female faces with morphology closer to average. The attractiveness of Nama women as rated by Nama men positively correlated with lighter complexion, but this did not extend to rating by Cameroonian men. The attractiveness of Namibian Owambo/Herero women was positively associated with facial femininity and lighter complexion when judged by both Cameroonian and Nama male raters. In all samples, the attractiveness as rated by Czech men was predicted by age and BMI, but not by skin color. We found no significant association between attractiveness and fluctuating asymmetry in any of the tested samples. When controlling for age, the effect of skin color on attractiveness turned to be non-significant in the Owambo/Herrero and Nama sample, but remained significant in the Cameroonian sample. Variations in skin color thus represent an important factor of African female attractiveness within the African context, but they do not seem to affect judgements made by European raters. Sensitivity to some facial markers of female attractiveness thus seems to be restricted to regional populations and/or constrained by shared ethnicity.     

African Negro

Abstract

Roger L. Stevens is Chairman of the Board of Trustees at the John F. Kennedy Center for the Performing Arts in Washington, D.C., which he championed and funded in its infant stage. Successful in the real estate business (he sold the Empire State Building at a fair profit) Mr. Stevens segued into the theatre, producing such Broadway shows as A Man For All Seasons, Tea and Sympathy, Annie and Deathtrap. He came to Washington as assistant to Lyndon B. Johnson and stayed to build the Kennedy Center and to develop a program which continues to be strong and diverse. Design's Executive Editor Jack Morrison, president of the American Theatre Association, recently interviewed Roger Stevens for our readers.     

African Fractals

This article examines the visual essay as a special verbal/visual mode of expression that is practised both by social scientists and social documentarians, although still on a very limited scale. Examining some of their commonalities and differences sheds light on the particularities of the scientific versus the social documentary approach more generally. To conclude, a photo‐essay from a social documentary photographer is discussed, as it comes close to what could be termed a sociological approach. This borderline application allows elaboration of some of the specifics of the visual essay as a mode of visual anthropology/sociology.     

African Hepatics

Abstract

Lophocolea bispinosa, new to the British Isles, is described in detail. This small dioecious species, which may have been introduced from New Zealand, is well established in the Isles of Scilly, especially in and around the Abbey Gardens in Tresco.     

African Hepatics

Abstract

A new species of Amphicephalozia, A. africana Váňa &; M. Wigginton from Mt Karisimbi, Rwanda is described and illustrated. This is the third species to be recognised from the genus.     

Elevated male European and female African contributions to the genomes of African American individuals

The differential relative contribution of males and females from Africa and Europe to individual African American genomes is relevant to mapping genes utilizing admixture analysis. The assessment of ancestral population contributions to the four types of genomic DNA (autosomes, X and Y chromosomes, and mitochondrial) with their differing modes of inheritance is most easily addressed in males. A thorough evaluation of 93 African American males for 2,018 autosomal single nucleotide polymorphic (SNP) markers, 121 X chromosome SNPs, 10 Y chromosome haplogroups specified by SNPs, and six haplogroup defining mtDNA SNPs is presented. A distinct lack of correlation observed between the X chromosome and the autosomal admixture fractions supports separate treatment of these chromosomes in admixture-based gene mapping applications. The European genetic contributions were highest (and African lowest) for the Y chromosome (28.46%), followed by the autosomes (19.99%), then the X chromosome (12.11%), and the mtDNA (8.51%). The relative order of admixture fractions in the genomic compartments validates previous studies that suggested sex-biased gene flow with elevated European male and African female contributions. There is a threefold higher European male contribution compared with European females (Y chromosome vs. mtDNA) to the genomes of African American individuals meaning that admixture-based gene discovery will have the most power for the autosomes and will be more limited for X chromosome analysis. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.