Climate‐driven mitochondrial selection: A test in Australian songbirds

Diversifying selection between populations that inhabit different environments can promote lineage divergence within species and ultimately drive speciation. The mitochondrial genome (mitogenome) encodes essential proteins of the oxidative phosphorylation (OXPHOS) system and can be a strong target for climate‐driven selection (i.e., associated with inhabiting different climates). We investigated whether Pleistocene climate changes drove mitochondrial selection and evolution within Australian birds. First, using phylogeographic analyses of the mitochondrial ND2 gene for 17 songbird species, we identified mitochondrial clades (mitolineages). Second, using distance‐based redundancy analyses, we tested whether climate predicts variation in intraspecific genetic divergence beyond that explained by geographic distances and geographic position. Third, we analysed 41 complete mitogenome sequences representing each mitolineage of 17 species using codon models in a phylogenetic framework and a biochemical approach to identify signals of selection on OXPHOS protein‐coding genes and test for parallel selection in mitolineages of different species existing in similar climates. Of 17 species examined, 13 had multiple mitolineages (range: 2–6). Climate was a significant predictor of mitochondrial variation in eight species. At least two amino acid replacements in OXPHOS complex I could have evolved under positive selection in specific mitolineages of two species. Protein homology modelling showed one of these to be in the loop region of the ND6 protein channel and the other in the functionally critical helix HL region of ND5. These findings call for direct tests of the functional and evolutionary significance of mitochondrial protein candidates for climate‐associated selection.     

An unusual phylogeography in the bushcricket Ephippiger ephippiger from Southern France

Pleistocene glaciations have played a major role in species divergence. The bushcricket Ephippiger ephippiger shows unusual patterns of intraspecific variation in multiple traits across Southern Europe. This is centred in Southern France, and evidence implies that it results from secondary contact after differentiation in Pleistocene refugia. However, the possible time scales involved, locations of the refugia and patterns of expansion remain obscure. This study sequenced the COII (507 BP) and cyt b (428 BP) mitochondrial genes to examine the intraspecific phylogeography of Western European samples of E. ephippiger. A minimum evolution tree revealed little resolution between described subspecies of E. ephippiger. Strikingly, populations from the Pyrenees and Mediterranean coastal region contained a complex genetic structure corresponding to major river valleys, independent of the traditional taxonomy. Samples of the subspecies E. e. vitium formed a distinct clade, perhaps supporting their taxonomic status. However, other forms (cruciger and cunii) were not genetically distinct, which is surprising given differences in their morphology and behaviour. The extent of the genetic divergence between Pyreneen valleys is unexpectedly deep, with average Tamura-Nei distances of around 14% (net distances of 11%) separating the main clades of coding COII sequences. Cyt b showed a similar pattern, but was confounded by some non-coding probable pseudogenes. If a conventional insect molecular clock is applied, these cryptic clades must pre-date the Pleistocene, and hypotheses for their history are discussed. However, mtDNA divergence in Ephippiger is not evolving in a clock-like manner, because a likelihood ratio test rejects clock assumptions for the COII sequences.     

Phylogeographic studies on natural populations of the South American fruit fly, <Emphasis Type="Italic">Anastrepha fraterculus</Emphasis> (Diptera: Tephritidae)

Anastrepha fraterculus is an important pest of commercial fruits in South America. The variability observed for morphological and behavioural traits as well as genetic markers suggests that A. fraterculus represents a complex of synmorphic species rather than a single biological species. We studied the correlation between geographical distribution and genetic variation in natural populations from Argentina and south Brazil. Fragments of the mitochondrial gene COII were sequenced in 28 individuals. The matrix of aligned sequences was phylogenetically analysed by parsimony, yielding a cladogram of haplotypes. Based on Templeton’s nested method, no clade showed any geographic pattern for the gene COII, indicating lack of significant association between haplotypic variability and geographic distribution. The analysis of nucleotide substitution distances by Neighbour-Joining algorithm showed that geographically distant populations exhibit low genetic distances. The corresponding trees clustered the populations without showing any geographic pattern. This result suggests that the populations studied are not reproductively isolated.     

Effect of a polymorphism in the ND1 mitochondrial gene on human skeletal muscle mitochondrial function

Objective: A non‐silent polymorphism in the mitochondrial coding region of the ND1 gene, a subunit of reduced nicotinamide adenine dinucleotide (NADH) dehydrogenase is associated with resting metabolic rate (RMR) in 245 non‐diabetic Pima Indians. The purpose of this investigation was to determine the effect of the ND1 gene polymorphism on mitochondrial function in 14 male Pima Indians. Methods and Procedures: Seven subjects with an A at site 3547 of the ND1 gene (Ile at amino acid 81), and seven with a G at this site (Val) were studied. Mitochondria were isolated from 0.8 to 1.5 g of skeletal muscle obtained by needle biopsy of the lateral quadriceps muscle. In intact mitochondria, maximal (state‐3) and resting (state‐4) respiration rates were measured polarographically at 37 °C with a variety of single substrates or substrate combinations. Disrupted mitochondria were analyzed for maximal capacities through the entire electron transport chain (ETC) (NADH oxidase (NADHOX)), as well as through a segment of Complex I that is independent of the ND1 component (NADH‐ferricyanide (NADH‐FeCN) reductase). Results: Mitochondria were well coupled and exhibited higher respiratory control ratios (RCRs) than rodent muscle. There were no differences between the two groups for any of the measured parameters. Discussion: These results indicate that the cause of the observed association between RMR and the ND1 polymorphism is not related to in vitro mitochondrial function.     

Genetic characterization of the mitochondrial DNA from Lepeophtheirus salmonis (Crustacea; Copepoda). A new gene organization revealed

The mitochondrial DNA (mtDNA) from the salmon louse, Lepeophtheirus salmonis, is 15445 bp. It includes the genes coding for cytochrome B (Cyt B), ATPase subunit 6 and 8 (A6 and A8), NADH dehydrogenase subunits 1-6 and 4L (ND1, ND2, ND3, ND4, ND4L, ND5 and ND6), cytochrome c oxidase subunits I-III (COI, COII and COIII), two rRNA genes (12S rRNA and 16S rRNA) and 22 tRNAs. Two copies of tRNA-Lys are present in the mtDNA of L. salmonis, while tRNA-Cys was not identified. Both DNA strands contain coding regions in the salmon louse, in contrast to the other copepod characterized Tigriopus japonicus, but only a few genes overlap. In vertebrates, ND4 and ND4L are transcribed as one bicistronic mRNA, and are therefore localized together. The same organization is also found in crustaceans, with the exceptions of T. japonicus, Neocalanus cristatus and L. salmonis that deviate from this pattern. Another exception of the L. salmonis mtDNA is that A6 and A8 do not overlap, but are separated by several genes. The protein-coding genes have a bias towards AT-rich codons. The mitochondrial gene order in L. salmonis differs significantly from the copepods T. japonicus, Eucalanus bungii, N. cristatus and the other 13 crustaceans previously characterized. Furthermore, the mitochondrial rRNA genes are encoded on opposite strands in L. salmonis. This has not been found in any other arthropods, but has been reported in two starfish species. In a phylogenetic analysis, using an alignment of mitochondrial protein sequences, L. salmonis groups together with T. japonicus, being distant relatives to the other crustaceans.     

Genetic study of the population of Tenerife (Canary Islands,Spain): Protein markers and review of classical polymorphisms

Data on six protein polymorphisms (19 alleles) from the human population of Tenerife are presented and discussed along with other classical markers in relation to the origin of the Canarians. Genetic influences from three population groups were considered: the Iberians, and the Berbers and non-Berbers (Arabs) from north Africa. The systems examined show the Tenerife population lies within the limits of variation described for various Iberian groups, with a slight tendency towards the characteristics of north African populations. When blood groups, red cell enzymes and serum protein data were considered, the similarity of the Canary population to Iberians seems strengthened (70% estimated contribution of Iberian peninsula genes to the present-day Canarian pool), while some relation with north African groups is shown. Genetic distances between Canarians and Arabs and Canarians and Berbers are lower than those between the two north African groups, indicating a relative and comparable contribution of each to the present-day gene pool of the Canarian population. The Arab contribution could be attributable to the slaves who were introduced to these islands after the conquest in the 15th century, while the Berber contribution could be the remnants of the extinct aboriginal peoples of the islands (Guanches) or a more recent immigration due to slavery. Genetic data do not allow us to distinguish between these two possibilities. Am. J. Phys. Anthropol. 102:337–349, 1997. © 1997 Wiley-Liss, Inc.     

Unexpected ceiling of genetic differentiation in the control region of the mitochondrial DNA between different subspecies of the ayu Plecoglossus altivelis

Sequence analyses of the non-coding, control region (CR) and coding region of the ND4-tRNA(Ser) genes in the mitochondrial DNA (mtDNA) were conducted for populations of the ayu Plecoglossus altivelis altivelis and the Ryukyu-ayu P. a. ryukyuensis. The level of genetic differentiation between the two subspecies evaluated from the CR data was substantially low, when comparing with that estimated from ND4-tRNA(Ser) gene region data, as well as those from nuclear genome data sets. By contrast, the differentiation between subspecies in the ND4-tRNA(Ser) gene region was substantial, being consistent with the results from the previous nuclear genome analyses. Results of UPGMA and minimum spanning network analyses also implied the unexpected ceiling of genetic differentiation in the CR. These results suggest that the CR does not reflect accurately the level of overall genetic differentiation between the populations of the ayu, but other coding regions of the mtDNA do reflect it so that the mtDNA on the whole may function as a rich source of useful markers for genetic assessment of populations of this species.     

No association between mitochondrial DNA haplotypes and a female-limited mimicry phenotype in Papilio glaucus

Abstract Alternative alleles at a locus on the W chromosome of Papilio glaucus (causing dark or yellow wing colors, respectively) underlie a female-limited mimicry polymorphism thought to be maintained by balancing selection. In species with heterogametic females (i.e., the ZZ-male/ZW-female sex chromosome system), the mitochondrial DNA and the W chromosome are genetically linked because they are both maternally transmitted. We investigate the association of COI and COII mitochondrial DNA haplotypes with alternative W-linked phenotypes. Surprisingly, we find no congruence between mitochondrial DNA genealogies and inferred W-linked color alleles in P. glaucus. Using a maximum-likelihood phylogenetic approach, we reject the hypothesis of monophyly for darkmorph mitochondrial DNA lineages, even in the presence of putative low-frequency mimicry suppressor alleles or alternative melanizing factors. The most likely genealogical tree topologies assume more than one exchange event between mitochondrial DNA cytotype and the W-linked color morph. These results suggest that there is either paternal leakage of mitochondrial DNA or that more than two W-linked alleles underlie the alternative color morphs. Using data from an additional mitochondrial DNA locus, ND5, we show that pairwise linkage disequilibrium decays with physical distance between polymorphic sites. This finding suggests that genetic exchanges between maternal and paternal mitochondrial DNAs may have contributed to the lack of association we observe between phenotype and genotype.     

Mitochondrial DNA sequence analysis of the cytochrome oxidase subunit II gene from Podospora anserina. A group IA intron with a putative alternative splice site

A 5 kb region of the 95 kb mitochondrial genome of Podospora anserina race s has been mapped and sequenced (1 kb = 10(3) base-pairs). This DNA region is continuous with the sequence for the ND4L and ND5 gene complex in the accompanying paper. We show that this sequence contains the gene for cytochrome oxidase subunit II (COII). This gene is 4 kb in length and is interrupted by a subgroup IB intron (1267 base-pairs (bp) in length) and a subgroup IA intron (1992 bp in length). This group IA intron has a long open reading frame (ORF; 472 amino acid residues) discontinuous with the upstream exon sequence. A putative alternative splice site is present, which brings the ORF into phase with the 5' exon sequence. The 5'- and 3'-flanking regions of the COII gene contain G + C-rich palindromic sequences that resemble similar sequences flanking many Neurospora crassa mitochondrial genes.     

Genetic differentiation of three sympatric charr species from genus Salvelinus inferred from PCR-RFLP analysis of mitochondrial DNA

We examined differentiation of three sympatric charr species Dolly Varden charr Salvelinus malma Walbaum, white-spotted charr S. leucomaenis Pallas, and Levanidov charr S. levanidovi Chereshnev, Scopetz, Gudkov. Using restriction fragment length polymorphism analysis (RFLP), three mitochondrial DNA fragments (ND1/ND2, ND5/ND6, and Cytb/D-loop) amplified in PCR were compared. The divergence of mtDNA nucleotide sequences between S. levanidovi and S. leucomaenis was about 9.7%, between S. levanidovi and S. malma, 8.7%, and between S. malma and S. laecomaenis, 7.5%. These results indicate genetic isolation of the species examined and support the earlier suggestion on closeness of Levanidov charr to the common ancestor of the genus Salvelinus.     

Nucleotide sequence of nine protein-coding genes and 22 tRNAs in the mitochondrial DNA of the sea starPisaster ochraceus

Summary We have cloned and sequenced over 9 kb of the mitochondrial genome from the sea starPisaster ochraceus. Within a continuous 8.0-kb fragment are located the genes for NADH dehydrogenase subunits 1, 2, 3, and 4L (ND1, ND2, ND3, and ND4L), cytochrome oxidase subunits I, II, and III (COI, COII, and COIII), and adenosine triphosphatase subunits 6 and 8 (ATPase 6 and ATPase 8). This large fragment also contains a cluster of 13 tRNA genes between ND1 and COI as well as the genes for isoleucine tRNA between ND1 and ND2, arginine tRNA between COI and ND4L, lysine tRNA between COII and ATPase 8, and the serine (UCN) tRNA between COIII and ND3. The genes for the other five tRNAs lie outside this fragment. The gene for phenylalanine tRNA is located between cytochrome b and the 12S ribosomal genes. The genes for tRNA^glu and tRNA^thr are 3 to the 12S ribosomal gene. The tRNAs for histidine and serine (AGN) are adjacent to each other and lie between ND4 and ND5. These data confirm the novel gene order in mitochondrial DNA (mtDNA) of sea stars and delineate additional distinctions between the sea star and other mtDNA molecules.     

Mitochondrial DNA sequence diversity in three ethnic populations from the South-west Iran: a preliminary study

To investigate the genetic structure of human populations in the South-west region of Iran, mitochondrial first hypervariable DNA sequences were obtained from 50 individuals representing three different ethnic groups from Khuzestan Province. Studied groups were Shushtari Persians and Chahar Lang Bakhtiyaries from Indo-European-speaking populations and Bani Torof Arabs from Semitic-speaking linguistic families. Genetic analysis of mtDNA data showed high similarity of Chahar Lang Bakhtiyaries with other Iranian Indo-European-speaking populations while Shushtaries and Bani Torofs had a closer affinity with Semitic-speaking groups rather than to other Iranian populations. The relationship of Chahar Lang Bakhtiyaries and Bani Torof Arabs with their neighbor populations can be explained by linguistic and geographic proximity. Whereas, the greater similarity of Shushtari Persians with West Asian Arabs is probably according to high gene flow between them. This article represents a preliminary study of three major ethnic groups of South-west Iran which investigates the potential genetic substructure of the region.     

Genetic differentiation in the winter pine processionary moth (Thaumetopoea pityocampa--wilkinsoni complex), inferred by AFLP and mitochondrial DNA markers

The winter pine processionary moth has become an important pine pest in the last century, as a consequence of the spread of pine cultivation in the Mediterranean region. The pattern of genetic differentiation of this group, that includes two sibling species (Thaumetopoea pityocampa and Th. wilkinsoni), has been studied in nine populations using amplified fragment length polymorphism (AFLP) and single strand conformation polymorphism-sequence analysis (SSCP) of the mitochondrial cytochrome oxidase 1 (COI) and cytochrome oxydase 2 (COII). Results indicate the existence of strong genetic differentiation between the two species that became separated before the Quaternary ice ages. Moreover data indicate that Th. pityocampa has a strong geographical structure, particularly evident at the nuclear level, where all pairwise phiST resulted to be highly significant and individuals from the same population resulted to be strongly clustered when an individual tree was reconstructed. The estimates of the absolute number of migrants between populations (Nm), obtained from mitochondrial and nuclear DNA markers, suggest that gene flow is low and that a gender-related dispersal could occur in this species. The males appear to disperse more than females, contributing to the genetic diversity of populations on a relatively wide range, reducing the risks of inbreeding and the genetic loss associated with bottlenecks occurring in isolated populations.     

The wheat cytochrome oxidase subunit II gene has an intron insert and three radical amino acid changes relative to maize

We have determined the sequence of the wheat mitochondrial gene for cytochrome oxidase subunit II (COII) and find that its derived protein sequence differs from that of maize at only three amino acid positions. Unexpectedly, all three replacements are non-conservative ones. The wheat COII gene has a highly-conserved intron at the same position as in maize, but the wheat intron is 1.5 times longer because of an insert relative to its maize counterpart. Hybridization analysis of mitochondrial DNA from rye, pea, broad bean and cucumber indicates strong sequence conservation of COII coding sequences among all these higher plants. However, only rye and maize mitochondrial DNA show homology with wheat COII intron sequences and rye alone with intron-insert sequences. We find that a sequence identical to the region of the 5' exon corresponding to the transmembrane domain of the COII protein is present at a second genomic location in wheat mitochondria. These variations in COII gene structure and size, as well as the presence of repeated COII sequences, illustrate at the DNA sequence level, factors which contribute to higher plant mitochondrial DNA diversity and complexity.     

Identification of Paramecium mitochondrial proteins using antibodies raised against fused mitochondrial gene products

Paramecium aurelia mitochondrial (mt) DNA fragments carrying the coding regions for two proteins, P1 (in the region adjacent to the origin of replication) and COII (subunit II of cytochrome oxidase), were used to study mt gene expression. The sequence for the portion of mtDNA containing P1 has already been described [Pritchard et al., Gene 44 (1986) 243-253]. The complete nucleotide sequence of the portion containing the COII gene is presented here. An 18.5-kDa protein was produced in maxicells when a fragment containing a major portion of the sequence coding for P1 was used. This fragment and a fragment carrying the COII gene were cloned into the expression vector pTRPLE', and antibodies were raised against the resulting fusion proteins in an Escherichia coli lysate. Western blots of Paramecium mt extracts identified two proteins, one 21 kDa (COII) and the other 23.5 kDa (P1). The size of the P1 protein is in agreement with the size of the open reading frame in that region of mitochondrial DNA. Based on extensive amino acid homology to the Paramecium gene and limited homology to COII genes from other organisms, the COII gene in another ciliate, Tetrahymena pyriformis, was identified just upstream of the small subunit rDNA in previously published sequences (Schnare et al., 1986). The size of the COII gene and the homology with the COII gene from Tetrahymena suggest that ATC, ATT, GTG and GTC could be used as translational initiators in Paramecium mitochondria.     

Somatic mutations of mitochondrial genome in hepatocellular carcinoma

Somatic mutations have been identified in mitochondrial DNA (mtDNA) of various human primary cancers. However, their roles in the pathophysiology of cancers are still unclear. In our previous study, high frequency of somatic mutations was found in the D-loop region of mtDNA of hepatocellular carcinomas (HCCs). In the present study, we examined 44 HCCs and corresponding non-cancerous liver tissues, and identified 13 somatic mutations in the coding region of mtDNAs from 11 HCC samples (11/44, 25%). Among the 13 mtDNA mutations, six mutations (T6787C, G7976A, A9263G, G9267A, A9545G and A11708G) were homoplasmic while seven mutations (956delC, T1659C, G3842A, G5650A, 11032delA, 12418insA and a 66 bp deletion) were heteroplasmic. Moreover, the G3842A transition created a premature stop codon and the 66 bp deletion could omit 22 amino acid residues in the NADH dehydrogenase (ND) subunit 1 (ND1) gene. The 11032delA and 12418insA could result in frame-shift mutation in the ND4 and ND5 genes, respectively. The T1659C transition in tRNA^Val gene and G5650A in tRNA^Ala gene were reported to be clinically associated with some mitochondrial disorders. In addition, the T6787C (cytochrome c oxidase subunit I, COI), G7976A (COII), G9267A (COIII) and A11708G (ND4) mutations could result in amino acid substitutions in the highly conserved regions of the affected mitochondrial genes. These mtDNA mutations (10/13, 76.9%) have the potential to cause mitochondrial dysfunction in HCCs. Taken these results together, we suggest that there may be a higher frequency of mtDNA mutations in HCC than in normal liver tissues from the same individuals.     

基于线粒体COI、Cytb和COII基因的中国草地螟不同地理种群遗传分化分析

【目的】揭示中国草地螟Loxostege sticticalis不同地理种群的遗传分化程度。【方法】采用PCR技术扩增中国西北和华北地区草地螟11个地理种群的线粒体 COI, Cytb和COII基因序列,基于其序列变异及单倍型贝叶斯系统发育树和单倍型网络图分析,探讨不同地理种群间的遗传距离、分子系统发生关系及遗传分化程度。【结果】草地螟11个地理种群的线粒体 COI, Cytb和COII基因序列分别有24, 12和69个变异位点(分别占总序列的3.6%, 2.7%和8.8%),检测到的单倍型分别为22, 14和16个,单倍型多样度(Hd)分别为0.7600, 0.5842和0.7341,核苷酸平均差异度(K)分别为1.704, 0.752和3.997,不同单倍型间的遗传距离平均值分别为0.004, 0.005和0.013。总种群的Tajima’s D和Fu’s Fs值皆不显著,表明草地螟不同地理种群间的遗传分化不明显,群体大小稳定。根据各地理种群的单倍型建立的系统发育树和单倍型网络图表明,各单倍型散布在不同的地理种群中,无明显的地理分布格局。【结论】草地螟各地理种群的遗传距离与地理距离间不具有显著的相关性,其遗传分化不明显。     

Widespread mito‐nuclear discordance with evidence for introgressive hybridization and selective sweeps in Lycaeides

We investigated the extent and potential cause(s) of mitochondrial introgression within the polytypic North American Lycaeides species complex (Lepidoptera). By comparing population genetic structure based on mitochondrial DNA (COI and COII) and nuclear DNA (251 polymorphic amplified fragment length polymorphism markers), we detected substantial mito‐nuclear discordance, primarily involving a single mitochondrial haplotype (h01), which is likely due to mitochondrial introgression between differentiated Lycaeides populations and/or species. We detected reduced mitochondrial genetic diversity relative to nuclear genetic diversity in populations where mitochondrial haplotype h01 occurs, suggesting that the spread of this haplotype was facilitated by selection. We found no evidence that haplotype h01 is associated with increased fitness (in terms of survival to eclosion, fresh adult weight, and adult longevity) in a polymorphic Lycaeides melissa population. However, we did find a positive association between mitochondrial haplotype h01 and infection by the endoparasitic bacterium Wolbachia in one out of three lineages tested. Linkage disequilibrium between mitochondrial haplotype h01 and Wolbachia infection status may have resulted in indirect selection favouring the spread of haplotype h01 in at least one lineage of North American Lycaeides. These results illustrate the potential for introgressive hybridization to produce substantial mito‐nuclear discordance and demonstrate that an individual's mitochondrial and nuclear genome may have strikingly different evolutionary histories resulting from non‐neutral processes and intrinsic differences in the inheritance and biology of these genomes.     

武铠蛱蝶线粒体基因组全序列测定和分析

【目的】了解闪蛱蝶亚科属间及种间的分子系统进化关系。【方法】采用PCR步移法对武铠蛱蝶 Chitoria ulupi 线粒体基因组全序列进行了测定和分析。基于线粒体基因组13个蛋白质编码基因的核苷酸序列构建了38种鳞翅目昆虫的系统发育树。【结果】分析结果表明,武铠蛱蝶线粒体基因组全长15 279 bp,包括13个蛋白质编码基因、22个tRNA基因、2个rRNA基因和一段长度为391 bp的A+T富含区,基因排列顺序与其他已知近缘种昆虫相同。武铠蛱蝶线粒体基因组中存在很高的A+T含量（79.9％）。13个蛋白质编码基因中,COII以TTG作为起始密码子,COI以CGA作为起始密码子外,其余均为昆虫典型的起始密码子ATN。COII和ND4基因使用了不完全终止密码子T,其余基因均以典型的TAA为终止密码子。在所测得的22个tRNA基因中,除tRNA^Ser(AGN)缺少DHU臂外,其余tRNA均能形成典型的三叶草结构。与其他多数鳞翅目昆虫一样,武铠蛱蝶的A+T富含区中有一段由ATAGAA引导的保守的多聚T结构,长度为21 bp,并散布着一些长短不一的串联重复单元。系统发育树结果显示,总科级别的系统发育关系为：卷蛾总科＋（凤蝶总科＋（螟蛾总科＋(夜蛾总科＋蚕蛾总科＋尺蛾总科)））;在蛱蝶科物种中,武铠蛱蝶与猫蛱蝶Timelaea maculate 亲缘关系最近。【结论】基于分子标记构建的鳞翅目昆虫系统发育关系与传统的形态学分类结果基本一致。     

Genetic variation at the ApoB 3'HVR, D2S44, and D7S21 loci in the Ewondo Ethnic Group of Cameroon.

A sample of the Ewondo population (a Bantu-speaking group of Southern Cameroon) was analyzed for the polymorphism at three tandem repeated DNA loci (ApoB 3' HVR, D2S44, and D7S21). We observed a greater number of ApoB 3' HVR alleles (17) and a significantly higher estimated heterozygosity (.879 +/- .011) than in previously surveyed populations, with the exception of U.S. Blacks. The higher genetic variability of Ewondo and U.S. Blacks was also shown by the ApoB 3' HVR allele-frequency spectra. A method for measuring population distances, based on cumulative fragment-size distribution, is described. Interpopulation comparisons for ApoB 3' HVR were carried out by this method and were compared with those obtained by a genetic distance measurement. The two sets of results showed a consistent pattern of population differentiation: the Ewondos and the U.S. Blacks clustered together and were well apart from both a Caucasian cluster (Swedes, U.S. Whites, Italians, and Germans) and other well-defined populations (Sikhs of India and Pehuence Indians of Chile). Profile distances were then computed from D2S44 and D7S21 bined data. This analysis indicated a genetic affinity between Ewondos, U.S. Blacks, and Afro-Caribbean Blacks and outlined the genetic diversity between Ewondos, Caucasians, and Asian Indians.