Population genetics of the metabolically related Adh,Gpdh and Tpi polymorphisms in Drosophila melanogaster I. Geographic variation in Gpdh and Tpi allele frequencies in different continents

Among Australasian populations from above 32.5° latitude there is a significant negative relationship between Gpdh ^F frequency and distance from the equator which is not explained by gametic disequilibrium with the linked inversion In(2L)t. This is consistent with the associations reported earlier for Gpdh ^F among populations covering comparable latitudes in North America and Europe/Asia. By contrast, Tpi allele frequencies are found to be significantly associated with distance from the equator in Australasia but not North America or Europe/Asia. The Tpi pattern in the different zones is essentially the same as that reported earlier for the Acph polymorphism, which maps only 0.2 cM away from the Tpi locus.There are now ten enzyme polymorphisms in D. melanogaster which have been screened for latitudinal associations in Australasia, North America and Europe/Asia. Allele frequencies at six of these loci show significant relationships with distance from the equator which are consistent across all three zones. These latitudinal associations are more prevalent for Group II than Group I enzymes. Values of genic heterozygosity averaged over the ten polymorphic loci and eleven other monomorphic systems do not vary with latitude but differ substantially between zones. Values of Nei's genetic distance between North American and European/Asian populations calculated from all 21 systems are equivalent to subspecific differences elsewhere in the genus.     

Chromosome inversion polymorphisms in Drosophila melanogaster II. Geographic clines and climatic associations in Australasia,North America and Asia

The four paracentric autosomal chromosome inversions In(2L)t, In(2R)NS, In(3L)P and In(3R)R are commonly polymorphic in natural populations of D. melanogaster in Australasia, North America and Asia, with latitudinal clines in the frequencies of each inversion in each region. In each region inversion frequency decreases with increasing distance from the equator, although the precise relationship between frequency and latitude varies between inversions and, for In(2L)t and In(2R)NS, among regions. Each inversion also shows a longitudinal cline in at least one region but none show such a cline in all three. Although no inversion's frequency is associated with the same climatic variable in all three regions, inversion frequencies are generally positively related to annual maximum temperature and, more particularly, minimum temperature and minimum rainfall. The directions of the latitudinal clines and the climatic associations are consonant with evidence from D. melanogaster that inversion frequencies decline in winter. They are also consonant with evidence from some other Drosophila species that inversion heterozygosities are lower at the geographic margins than at the centre of the species' ranges.     

Genetic divergence analysis of the Common Barn Owl Tyto alba (Scopoli, 1769) and the Short-eared Owl Asio flammeus (Pontoppidan, 1763) from southern Chile using COI sequence

In this paper new mitochondrial COI sequences of Common Barn Owl Tyto alba (Scopoli, 1769) and Short-eared Owl Asio flammeus (Pontoppidan, 1763) from southern Chile are reported and compared with sequences from other parts of the World. The intraspecific genetic divergence (mean p-distance) was 4.6 to 5.5% for the Common Barn Owl in comparison with specimens from northern Europe and Australasia and 3.1% for the Short-eared Owl with respect to samples from north America, northern Europe and northern Asia. Phylogenetic analyses revealed three distinctive groups for the Common Barn Owl: (i) South America (Chile and Argentina) plus Central and North America, (ii) northern Europe and (iii) Australasia, and two distinctive groups for the Short-eared Owl: (i) South America (Chile and Argentina) and (ii) north America plus northern Europe and northern Asia. The level of genetic divergence observed in both species exceeds the upper limit of intraspecific comparisons reported previously for Strigiformes. Therefore, this suggests that further research is needed to assess the taxonomic status, particularly for the Chilean populations that, to date, have been identified as belonging to these species through traditional taxonomy.     

中国球藓属(丛藓科)植物分布新资料

报道了球藓密疣变种在中国的新分布。该变种主要分布于欧洲、大洋洲和北美洲,在中国为首次记录。该文对其形态特征进行了详细的描述与拍照,凭证标本存放于内蒙古大学植物标本馆(HIMC)。     

African origin and global distribution patterns: Evidence inferred from phylogenetic and biogeographical analyses of ectomycorrhizal fungal genus Strobilomyces

Aim

The ectomycorrhizal genus Strobilomyces is widely distributed throughout many parts of the world, but its origin, divergence and distribution patterns remain largely unresolved. In this study, we aim to explore the species diversity, distribution and evolutionary patterns of Strobilomyces on a global scale by establishing a general phylogenetic framework with extensive sampling.

Location

Africa, Australasia, East Asia, Europe, North America, Central America and Southeast Asia.

Methods

The genealogical concordance phylogenetic species recognition method was used to delimit phylogenetic species. Divergence times were estimated using a Bayesian uncorrelated lognormal relaxed molecular clock. The ancestral area and host of Strobilomyces were inferred via the programs rasp and mesquite . The change of diversification rate over time was estimated using Ape, Laser and Bammtools software packages.

Results

We recognize a novel African clade and 49 phylogenetic species with morphological evidence, including 18 new phylogenetic species and 23 previously described ones. Strobilomyces probably originated in Africa, in association with Detarioideae/Phyllanthaceae/Monotoideae during the early Eocene. The dispersal to Southeast Asia can be explained by Wolfe's “Boreotropical migration” hypothesis. East Asia, Australasia, Europe and North/Central America are primarily the recipients of immigrant taxa during the Oligocene or later. A rapid radiation implied by one diversification shift was inferred within Strobilomyces during the Miocene.

Main conclusions

An unexpected phylogenetic species diversity within Strobilomyces was uncovered. The highest diversity, resulting probably from a rapid radiation, was found in East Asia. Dispersal played an important role in the current distribution pattern of Strobilomyces. The Palaeotropical disjunction is explained by species dispersal from Africa to Southeast Asia through boreotropical forests during the early Eocene. Species from the Northern Hemisphere and Australasia are largely derived from immigrant ancestors from Southeast Asia.     

Apparent overdominance of enzyme specific activity in two marine bivalves

Electrophoretic examination of a natural population sample of 332 mussels (Mytilus trossulus) revealed ten active allozyme alleles for the octopine dehydrogenase (Odh) locus and a statistically significant (P<0.005) departure from expected genotypic proportions caused by a deficiency of heterozygous genotypes. In vitro specific activity for octopine dehydrogenase (E.C. 1.5.1.11) was determined for 207 mussels representing 17 different Odh genotypes. Odh heterozygotes had an average specific activity that was 19% greater than that of apparently homozygous genotypes, a significant (P<0.05) difference. Electrophoretic examination of a natural population sample of 209 oysters (Crassostrea virginica) revealed 23 active allozyme alleles for the leucine aminopeptidase-2 (Lap-2) locus and a non-significant (P>0.05) deficiency of heterozygous genotypes. In vitro specific activity for leucine aminopeptidase (E.C. 3.4.-.-) was determined for 89 oysters representing 19 different Lap-2 genotypes. Lap-2 heterozygotes had an average specific activity that was 56% greater than that of homozygous genotypes, a significant (P<0.0001) difference. Possible explanations for the apparent overdominance in enzyme specific activity and the deficiency of heterozygotes include null alleles, molecular imprinting and aneuploidy.     

A long-term study on interactions between the Adh and αGpdh allozyme polymorphisms and the chromosomal inversion In(2L)t in a seminatural population of D. melanogaster

The Adh and αGpdh allozyme loci (both located on the second chromosome) showed considerable fluctuations in allele frequencies in a seminatural population of Drosophila melanogaster during 1972–97. Both long-term and short-term fluctuations were observed. The short-term fluctuations occurred within almost all years and comparison of allele frequencies between winters and summers showed significantly higher Adh^S (P < 0.001) and αGpdh^F (P < 0.01) allele frequencies in summers. Frequencies of these alleles were significantly positively correlated with environmental temperature, suggesting the adaptive significance of these allozyme polymorphisms. Frequency changes of the Odh locus (located on the third chromosome) showed no seasonal pattern and were not correlated with environmental temperature. Almost all short-term and long-term increases in Adh^S frequency were accompanied by a corresponding decrease in αGpdh^S frequency (r = –0.82, P < 0.001) and vice versa. Further analysis showed that gametic disequilibria between the Adh and αGpdh loci, which frequently occurred, were due to the presence of inversion In(2L)t located on the same chromosome arm and In(2L)t frequencies were positively correlated with environmental temperature. Gametic disequilibria between Adh and Odh and between Odh and αGpdh were hardly observed. Because In(2L)t is exclusively associated with the Adh^S/αGpdh^F allele combination, the observed correlated response in Adh/αGpdh allele frequencies is (at least partly) explained by hitchhiking effects with In(2L)t. This means that the adaptive value of the allozyme polymorphisms has been overestimated by ignoring In(2L)t polymorphism. Fluctuations in Adh allele frequencies are fully explained by selection on In(2L)t polymorphism, whereas we have shown that αGpdh frequency fluctuations are only partly explained by chromosomal hitchhiking, indicating the presence of selective differences among αGpdh genotypes in relation with temperature and independent of In(2L)t. Frequency fluctuations of αGpdh and In(2L)t are consistent with their latitudinal distributions, assuming that temperature is the main environmental factor varying with latitude that causes directly or indirectly these frequency distributions. However, the results of the tropical greenhouse population show no correlation of Adh (independent of In(2L)t) and Odh allele frequencies with environmental temperature, which may indicate that the latitudinal distribution in allele frequencies for these loci is not the result of selection on the F/S polymorphism in a direct way.     

Virulence of entomopathogenic hypocrealean fungi infecting <Emphasis Type="Italic">Anoplophora glabripennis</Emphasis>

Twenty isolates of four species of entomopathogenic hypocrealean fungi (Beauveria bassiana, Beauveria brongniartii, Isaria farinosa, and Metarhizium anisopliae) were found to be pathogenic to adults of the Asian longhorned beetle, Anoplophora glabripennis. Survival times for 50% of the beetles tested (ST₅₀) ranged from 5.0 (M. anisopliae ARSEF 7234 and B. brongniartii ARSEF 6827) to 24.5 (I. farinosa ARSEF 8411) days. Screening studies initially included strains of B. brongniartii, which is registered as a microbial control agent in Europe, Asia and South America but not in North America. At that time, we could not confirm that this fungal species is native to North America which added uncertainty regarding future registration of this species for pest control in the USA. Therefore, subsequent bioassays documented median survival times for three M. anisopliae isolates (5–6 days to death) and two of these isolates are suggested for further development because they are already registered for pest control in the USA. An erratum to this article can be found at     

The distribution of Gc subtypes among the Mongoloid populations

The polymorphism of Gc (group-specific components) has been investigated for a series of 3,160 individual samples from 11 Mongoloid populations in Asia and North and South America by isoelectric focusing on polyacrylamide gels. The samples fall into six Gc phenotypes which can be explained by the three common alleles, Gc^1F, Gc^1S, and Gc², together with several variant phenotypes explained as the heterozygotes for the three common alleles. The distribution of Gc^1F suballele appears to be considerably different from population to population among Mongoloids, ranging from 0.105 (Machiguenga Indans, Peru) to 0.609 (Kadazan, Borneo). A clear geographic cline from Southeast Asia into South America in Gc^1F allele was observed in the populations. In general, Gc^1F allele frequencies are lower in European populations and higher in African populations. The range of variability in the Gc^1F values observed among the Asiatic populations is between the Africans and the Europeans.     

基于CLIMEX的2种核桃蚜虫潜在适生区分析

【目的】分析核桃黑斑蚜与核桃全斑蚜在全球范围内的潜在分布,比较气候变化对其分布的影响,为核桃有害生物综合管理策略的制定提供依据。【方法】基于实验室和野外试验,结合CLIMEX软件对核桃黑斑蚜与核桃全斑蚜在目前及未来气候条件下的潜在地理分布进行了模拟和系统评估。【结果】2种核桃蚜虫适生区十分相似,在世界范围内主要分布区集中在欧洲、北美洲、亚洲等区域,核桃黑斑蚜适生区范围大于核桃全斑蚜,但在我国,核桃黑斑蚜适生区范围小于核桃全斑蚜。气候变化将决定2种蚜虫分布的差异性,未来气候情景下,2种蚜虫适生区将发生变化,在欧洲、北美洲和亚洲适生区范围向高纬度延伸;在我国适生区范围逐渐减小。【结论】在世界范围内,核桃黑斑蚜与核桃全斑蚜适生区域主要分布在25°N-75°N内的亚洲、欧洲、北美洲的部分地区;在我国,其适生区域主要分布在东部季风区内的东北的南部、西北东南部、西南中部、华中北部以及华北地区。     

Genetic characterisation by isoenzyme markers of North American and Australasian isolates of species of Sarcocystis (Protozoa: Apicomplexa) from mice,sheep, goats and cattle

The technique of isoenzyme (enzyme isotype) electrophoresis was used to compare genetic profiles of extracts of zoites of sarcocysts from North America and Australasia. The species examined were Sarcocystis muris (Railliet, 1886) from mice, S. gigantea (Railliet, 1886) (syn. S. ovifelis Heydorn et al., 1975) from sheep, S. capracanis Fischer, 1979 from goats and S. cruzi (Hasselmann, 1923) (syn. S. bovicanis Heydorn et al., 1975) from cattle. Sarcocysts from the four host animals had different alleles at almost all loci studied. This was not affected by having a common definitive host. Extracts of two cat-borne Sarcocystis species shared alleles at only 3 out of 16 loci, while two dog-borne Sarcocystis species had different alleles at 8 out of 16 loci. The extent of genetic divergence among sarcocysts confirmed the existance of distinct species in each host sampled. By contrast, the isolates from the United States of America and Australasia for any particular host were essentially identical, sharing at least one allele at every locus tested. ac]19860908     

Cytogeography of Solidago gigantea (Asteraceae) and its invasive ploidy level

Aim Newly formed polyploids experience problems of establishment and spread similar to those faced by newly introduced alien species. To understand the significance of polyploidy in biological invasions, we mapped the distribution of ploidy levels in Solidago gigantea Aiton in its native range in North America, and in Europe and East Asia where it is invasive. Location North America, Europe and East Asia. Methods Flow cytometry was used to measure ploidy levels in a total of 834 plants from 149 locations. Together with data from contributors and a literature review, ploidy‐level data were assembled for 336 locations. Cytogeographical maps from North America and Europe were prepared, incorporating new and previously published ploidy‐level data. Results In the native range, diploid, tetraploid and hexaploid plants were found, and also one triploid and one pentaploid plant (2n = 3x and 2n = 5x, respectively, each being new reports for this species). There was a high degree of geographical separation among the ploidy levels, and populations with mixed ploidy were rare. However, four zones were identified where plants of different ploidy could come into contact. In Europe and East Asia, only tetraploid plants were found. Main conclusions The geographical pattern in North America suggests that the ploidy levels are ecologically differentiated, although further investigations are needed to identify the nature of these differences. Alien populations appear to be exclusively tetraploid, but it is not clear whether this is because tetraploids were selectively introduced or because diploids were unsuccessful. In any case, comparisons between native and introduced populations need to account for ploidy level.     

Human skin color diversity is highest in sub-Saharan African populations

Previous studies of genetic and craniometric traits have found higher levels of within-population diversity in sub-Saharan Africa compared to other geographic regions. This study examines regional differences in within-population diversity of human skin color. Published data on skin reflectance were collected for 98 male samples from eight geographic regions: sub-Saharan Africa, North Africa, Europe, West Asia, Southwest Asia, South Asia, Australasia, and the New World. Regional differences in local within-population diversity were examined using two measures of variability: the sample variance and the sample coefficient of variation. For both measures, the average level of within-population diversity is higher in sub-Saharan Africa than in other geographic regions. This difference persists even after adjusting for a correlation between within-population diversity and distance from the equator. Though affected by natural selection, skin color variation shows the same pattern of higher African diversity as found with other traits.     

The historical ecology of yellow perch (Perca flavescens[Mitchill]) and their parasites

Aim To determine the origins of the host–parasite association between among yellow perch (Perca flavescens[Mitchill]) and the parasites Crepidostomum cooperi Hopkins, Proteocephalus pearsei La Rue and Urocleidus adspectus Beverly Burton. Of secondary interest are the parasites Bunodera luciopercae (Muller) and Proteocephalus percae (Muller) predictably associated with the Eurasian perch. Location The areas considered are the Holarctic, since the upper‐Cretaceous, and contemporary North America. Methods Published and new information from host and parasite phylogenies, palaeontology, palaeogeography and plate tectonics and host biology is incorporated to assess the origins of yellow perch and several of its parasites. This information is used to determine the origins for these host–parasite associations. Results Cladistic analysis suggests a Laurasian origin for Percidae and Perca, and that Perca is sister to the other genera in the family. Parasite phylogenies support a North American origin for the three species associated with yellow perch and a Laurasian origin for B. luciopercae. Proteocephalus pearsei and P. percae are not sister taxa. The fossil record for Perca dates to the Miocene in Europe and the Pleistocene in North America. North America and Europe were connected across the North Atlantic since at least the upper Cretaceous with separation complete by the Miocene. Europe was separated from Asia by the Obik Sea from the late Cretaceous until the Oligocene. Western cordillera orogeny and its accompanying high rates of water flow and Pleistocene glaciation represent barriers to Perca dispersal. Main conclusions The origin of Perca in North America dates at least to the late Oligocene when North America and Europe were connected across the North Atlantic and Europe and Asia were separate landmasses, and does not result from Pleistocene dispersal across Beringia from Asia. The present disjunction of Perca species in North America and Europe is due to the vicariant separation of North America and Europe. Based on the available information, yellow perch and its parasites have a North America origin. The association between yellow perch and the parasites in all cases is a consequence of host switching from other sympatric host species in North America and is not explained by co‐speciation. Even the association between the host‐specific Urocleidus adspectus and yellow perch originated with a host switch and is not due to co‐speciation. The basis for this host switching is geographical and ecological sympatry, especially shared feeding habits, with other North American fish hosts.     

Geographic pattern of genetic variation in the fox tapeworm Echinococcus multilocularis

Intraspecific genetic variation of Echinococcus multilocularis, the etiologic agent of human alveolar echinococcosis, has been evaluated among 76 geographic isolates from Europe, Asia and North America by using sequence data of mitochondrial and nuclear DNA. Relatively low genetic variation was found only in the mitochondrial DNA sequence consisting of 3 protein-coding genes. Pairwise divergence among the resultant 18 haplotypes ranged from 0.03 to 1.91%. Phylogenetic trees and parsimony network of these haplotypes depicted a geographic division into European, Asian and North American clades, but 1 haplotype from Inner Mongolia was unrelated to other haplotypes. The coexistence of the Asian and North American haplotypes could be seen, particularly on the St. Lawrence Island in the Bering Sea. These data suggest an evolutionary scenario in which distinct parasite populations derived from glacial refugia have been maintained by indigenous host mammals. The nuclear DNA sequence for the immunodominant B cell epitope region of ezrin/radixin/moesin-like protein (elp) was extremely conservative, indicating that the elp antigen is available for immunodiagnosis in any endemic areas.     

Invasion history of North American Canada thistle,Cirsium arvense

Aim Canada thistle (Cirsium arvense– Cardueae, Asteraceae) is one of the worst invasive plants world‐wide. Native to Eurasia, its unintentional introduction into North America now threatens the native flora and is responsible for enormous agricultural losses. The goals of this study are to: (1) reconstruct the evolutionary history of C. arvense and estimate how often it may have colonized North America, (2) compare the genetic diversity between European and North American populations to detect signs of demographic bottlenecks and/or patterns of population admixture, and (3) conduct bioclimatic comparisons to infer eventual niche shifts following this species’ introduction into North America. Location Europe and North America. Methods A total of 1522 individuals from 58 populations were investigated with six microsatellite markers. Estimates of heterozygosity (H_E) and allelic richness (R_S) were quantified for each population, and population structure was inferred via analyses of molecular variance (AMOVAs), principal components analyses (PCAs), Mantel tests and Bayesian clustering analyses. Climatic niche spaces were based on 19 bioclimatic variables extracted from approximately 32,000 locations covering the entire range, and compared using PCA and hierarchical cluster analysis. Results Although there is evidence of multiple introductions from divergent European lineages, North American populations of C. arvense exhibited significantly lower levels of genetic diversity than their putative ancestors. Bioclimatic comparisons pointed to a high degree of niche conservatism during invasion, but indicated that genotypes from the former USSR and Central European mountain chains were probably best adapted to invade North America upon entry into the continent. Main conclusions Genetic and historical data suggest that C. arvense first entered North America from Western Europe with the first European settlers, and was later introduced from Eastern Europe into the prairie states during the agricultural boom. The species went through a significant bottleneck following its introduction into the New World, but the level of genetic diversity remained high owing to admixture between genetically differentiated lineages and to a highly efficient outcrossing breeding system.     

Characterization of microsatellite loci for the Chinese mitten crab,Eriocheir sinensis

The Chinese mitten crab, Eriocheir sinensis is an important human food source in Asia and causes considerable ecological and economical damage as a recent invader of North America and Europe. Here we report the isolation and characterization of 12 highly polymorphic microsatellite loci for E. sinensis. The number of observed alleles per locus ranged from 7 to 40 and the observed heterozygosity from 0.50 to 0.95. These markers should prove a useful tool to investigate the colonization process and its evolutionary implications.     

Demographic expansion and genetic load of the halophyte model plant Eutrema salsugineum

The halophyte model plant Eutrema salsugineum (Brassicaceae) disjunctly occurs in temperate to subarctic Asia and North America. This vast, yet extremely discontinuous distribution constitutes an ideal system to examine long‐distance dispersal and the ensuing accumulation of deleterious mutations as expected in expanding populations of selfing plants. In this study, we resequenced individuals from 23 populations across the range of E. salsugineum. Our population genomic data indicate that E. salsugineum migrated “out of the Altai region” at least three times to colonize northern China, northeast Russia and western China. It then expanded its distribution into North America independently from northeast Russia and northern China, respectively. The species colonized northern China around 33.7 thousand years ago (kya) and underwent a considerable expansion in range size approximately 7–8 kya. The western China lineage is likely a hybrid derivative of the northern China and Altai lineages, originating approximately 25–30 kya. Deleterious alleles accumulated in a stepwise manner from (a) Altai to northern China and North America and (b) Altai to northeast Russia and North America. In summary, E. salsugineum dispersed from Asia to North America and deleterious mutations accumulated in a stepwise manner during the expansion of the species’ distribution.     

Geographic variation in the field response of male European pine sawflies, Neodiprion sertifer, to different pheromone stereoisomers and esters

The European pine sawfly, Neodiprion sertifer (Geoffroy) (Hymenoptera: Diprionidae), is a widespread and economically important forest insect. The sex pheromone communication system of this species has been previously investigated in North America, Japan and Europe, with the acetate or propionate of the alcohol (2S,3S,7S)-3,7-dimethyl-2-pentadecanol (diprionol) shown to be the main pheromone component. In some locations, male attraction either increased or decreased by the addition of the (2S,3R,7R)-diprionyl acetate isomer. However, these studies were made with different batches of synthetic pheromones, with different types of traps and according to different procedures, so the observed differences might not reflect true geographic variation. Here we investigate the geographic pattern of male sawfly response by using identical chemicals, traps and experimental procedures at eight field sites ranging from Japan in the east to Canada in the west. We found an increased inhibitory effect of the (2S,3R,7R)-isomer from Japan and Siberia to Europe. At the eastern sites, increasing amounts of the (2S,3R,7R)-isomer up to and equal to the amount of the (2S,3S,7S )-isomer, did not influence the trap catch, whereas at sites in Europe, as little as 1% of the (2S,3R,7R)-isomer almost completely inhibited the attraction. The response of the North American population was intermediate. The only site in which the (2S,3R,7R)-isomer was essential for the attraction of males was in Siberia. A similar pattern was found for the (2S,3R,7S)-isomer. Both the acetate and the propionate form of the (2S,3S,7S)-isomer were attractive by themselves in Japan, Europe and North America, and neither the (2S,3R,7S)-isomer nor the (2S,3R,7R)-isomer alone were attractive, in the acetate or propionate form. We discuss the significance of our findings for the development of more efficient monitoring schemes and for the causes of population divergence and speciation in the European pine sawfly.     

Analysis ofHLA-DR and -DQ gene polymorphisms in sudanese patients with type 1 (insulin-dependent) diabetes

In this study we report for the first time, the molecular analysis of HLA-DR and -DQ gene frequencies in a large cohort of well charaterized type 1 (insulin-dependent) diabetes mellitus (IDDM) patients (n=72), and ethnically matched controls (n=59) collected in subSaharan Africa. High molecular mass DNA was prepared and analyzed in Southern blots with DRBI, DQA1, and DQB1 probes. By identifying DR and DQ allele-specific restriction fragment length polymorphisms (RFLPs), we have shown a strong positive association between IDDM and the Asp 57^– DQB1 allele *0201 (DQw2). A rare DR4, DQw2 haplotype was also identified at high frequency in the IDDM cohort. We can now confirm that the association between Asp 57^–DQB1 alleles and IDDM, previously reported in ethnically diverse cohorts collected in Western Europe, North America, and South Asia, is also present in an IDDM cohort collected in Africa.