Derek F. Roberts

Bio: Derek F. Roberts is an academic researcher from Newcastle University. The author has contributed to research in topics: Population & Allele frequency. The author has an hindex of 21, co-authored 64 publications receiving 3458 citations. Previous affiliations of Derek F. Roberts include University of Baghdad.

Genetic effects of population size reduction.

Abstract: How far do accidental sampling errors in small populations influence their genetic make-up ? Detailed pedigrees of the population of Tristan da Cunha have been used to give an answer to this question.

Secular trends in genetic structure: an isonymic analysis of Northumberland parish records.

Abstract: SummaryFrom an isonymic analysis of marriages in Northumberland parishes in the 17th and 18th centuries, inbreeding is estimated. Levels suggest a high degree of localization of mating, and a restricted gene pool. Secular trends in inbreeding and differences between parishes emerge, which appear to correlate with historical events.

Environmental correlations of skin colour

Abstract: SummarySkin colour data obtained by reflectance spectrophotometry on indigenous populations are compared with environmental variables—latitude, temperature, humidity and altitude. Association with latitude predominates at all wavelengths. Temperatures show a small but appreciable association at the shorter wavelengths, humidity at wavelengths above 595 nm. Over 80 per cent of the total interpopulation variance at each wavelength is accounted for by these variables, more at the shorter wavelengths. It is suggested that skin colour should be regarded as a complex of entities of differing selective values rather than a single entity.

The founding mitochondrial DNA lineages of Tristan da Cunha Islanders.

Abstract: Genealogical histories show that the inhabitants of Tristan da Cunha are derived from a known number of founders. Using the transmission of mitochondrial DNA (mtDNA) from mother to offspring pairs, we traced the mtDNA types found in 161 extant individuals to five female founders. Although the historical data claimed that two pairs of sisters were among the founding females, mtDNA data showed support for only one pair of sisters. We also studied the fidelity of mtDNA transmission in conjunction with the genealogical data. We did not detect any mutations from 698 base pairs of sequence data from 75 individuals, which together accounted for 108 independent transmissions of mtDNA from mother to offspring. Based on this observation, we estimate that the mtDNA mutation rate is no more than one new mutation every 36 transmissions. These results indicate a high fidelity of maternal mtDNA transmission and support the utility of mtDNA in evolutionary and forensic studies. Am J Phys Anthropol 104:157–166, 1997. © 1997 Wiley-Liss, Inc.

Principal components analysis corrects for stratification in genome-wide association studies

Abstract: Population stratification—allele frequency differences between cases and controls due to systematic ancestry differences—can cause spurious associations in disease studies. We describe a method that enables explicit detection and correction of population stratification on a genome-wide scale. Our method uses principal components analysis to explicitly model ancestry differences between cases and controls. The resulting correction is specific to a candidate marker’s variation in frequency across ancestral populations, minimizing spurious associations while maximizing power to detect true associations. Our simple, efficient approach can easily be applied to disease studies with hundreds of thousands of markers. Population stratification—allele frequency differences between cases and controls due to systematic ancestry differences—can cause spurious associations in disease studies 1‐8 . Because the effects of stratification vary in proportion to the number of samples 9 , stratification will be an increasing problem in the large-scale association studies of the future, which will analyze thousands of samples in an effort to detect common genetic variants of weak effect. The two prevailing methods for dealing with stratification are genomic control and structured association 9‐14 . Although genomic control and structured association have proven useful in a variety of contexts, they have limitations. Genomic control corrects for stratification by adjusting association statistics at each marker by a uniform overall inflation factor. However, some markers differ in their allele frequencies across ancestral populations more than others. Thus, the uniform adjustment applied by genomic control may be insufficient at markers having unusually strong differentiation across ancestral populations and may be superfluous at markers devoid of such differentiation, leading to a loss in power. Structured association uses a program such as STRUCTURE 15 to assign the samples to discrete subpopulation clusters and then aggregates evidence of association within each cluster. If fractional membership in more than one cluster is allowed, the method cannot currently be applied to genome-wide association studies because of its intensive computational cost on large data sets. Furthermore, assignments of individuals to clusters are highly sensitive to the number of clusters, which is not well defined 14,16 .

The WEIRDest People in the World

Abstract: Behavioral scientists routinely publish broad claims about human psychology and behavior in the world's top journals based on samples drawn entirely from Western, Educated, Industrialized, Rich, and Democratic (WEIRD) societies. Researchers - often implicitly - assume that either there is little variation across human populations, or that these "standard subjects" are as representative of the species as any other population. Are these assumptions justified? Here, our review of the comparative database from across the behavioral sciences suggests both that there is substantial variability in experimental results across populations and that WEIRD subjects are particularly unusual compared with the rest of the species - frequent outliers. The domains reviewed include visual perception, fairness, cooperation, spatial reasoning, categorization and inferential induction, moral reasoning, reasoning styles, self-concepts and related motivations, and the heritability of IQ. The findings suggest that members of WEIRD societies, including young children, are among the least representative populations one could find for generalizing about humans. Many of these findings involve domains that are associated with fundamental aspects of psychology, motivation, and behavior - hence, there are no obvious a priori grounds for claiming that a particular behavioral phenomenon is universal based on sampling from a single subpopulation. Overall, these empirical patterns suggests that we need to be less cavalier in addressing questions of human nature on the basis of data drawn from this particularly thin, and rather unusual, slice of humanity. We close by proposing ways to structurally re-organize the behavioral sciences to best tackle these challenges.

The genetic legacy of the Quaternary ice ages

Abstract: Global climate has fluctuated greatly during the past three million years, leading to the recent major ice ages. An inescapable consequence for most living organisms is great changes in their distribution, which are expressed differently in boreal, temperate and tropical zones. Such range changes can be expected to have genetic consequences, and the advent of DNA technology provides most suitable markers to examine these. Several good data sets are now available, which provide tests of expectations, insights into species colonization and unexpected genetic subdivision and mixture of species. The genetic structure of human populations may be viewed in the same context. The present genetic structure of populations, species and communities has been mainly formed by Quaternary ice ages, and genetic, fossil and physical data combined can greatly help our understanding of how organisms were so affected.

The International HapMap Project

Abstract: The goal of the International HapMap Project is to determine the common patterns of DNA sequence variation in the human genome and to make this information freely available in the public domain. An international consortium is developing a map of these patterns across the genome by determining the genotypes of one million or more sequence variants, their frequencies and the degree of association between them, in DNA samples from populations with ancestry from parts of Africa, Asia and Europe. The HapMap will allow the discovery of sequence variants that affect common disease, will facilitate development of diagnostic tools, and will enhance our ability to choose targets for therapeutic intervention.

The Structure of Haplotype Blocks in the Human Genome

Abstract: Haplotype-based methods offer a powerful approach to disease gene mapping, based on the association between causal mutations and the ancestral haplotypes on which they arose. As part of The SNP Consortium Allele Frequency Projects, we characterized haplotype patterns across 51 autosomal regions (spanning 13 megabases of the human genome) in samples from Africa, Europe, and Asia. We show that the human genome can be parsed objectively into haplotype blocks: sizable regions over which there is little evidence for historical recombination and within which only a few common haplotypes are observed. The boundaries of blocks and specific haplotypes they contain are highly correlated across populations. We demonstrate that such haplotype frameworks provide substantial statistical power in association studies of common genetic variation across each region. Our results provide a foundation for the construction of a haplotype map of the human genome, facilitating comprehensive genetic association studies of human disease.