Increased geographic sampling reveals considerable new genetic diversity in the morphologically conservative African Pygmy Mice (Genus Mus; Subgenus Nannomys)

African endemic pygmy mice (Genus Mus; sub-genus Nannomys) have considerable economic and public health significance, and some species exhibit novel sex determination systems, making accurate knowledge of their phylogenetics and distribution limits important. This phylogenetic study was based on the mitochondrial control region and cytochrome b gene, for which a substantial body of published data was available. Study specimens were sourced from eight previously unsampled or poorly sampled countries, and include samples morphologically identified as Mus bufo, M. indutus, M. callewaerti, M. triton and M. neavei. These analyses increase the known genetic diversity of Nannomys from 65 to 102 haplotypes; at least 5 unassigned haplotypes are distinguished by potentially species-level cytochrome b genetic distances. The monophyly of Nannomys is supported. Mus musculoides, M. callewaerti, M. indutus, M. bufo, M. haussa, M. mattheyi, M. baoulei and M. sorella are supported as discrete species. The range of M. indutus is extended to include Botswana. M. setulosus and M. minutoides appear to be species complexes. A south and east African M. minutoides clade was defined and includes 8 new haplotypes out of 15. M. setulosus sensu lato includes M. setulosus sensu stricto and a strongly-supported M. bufo clade. Two samples, morphologically identified as M. triton and M. neavei, fall within the M. minutoides clade.     

Evolution of the Iga Heavy Chain Gene in the Genus Mus

To examine questions of immunoglobulin gene evolution, the IgA alpha heavy chain gene from Mus pahari, an evolutionarily distant relative to Mus musculus domesticus, was cloned and sequenced. The sequence, when compared to the IgA gene of BALB/c or human, demonstrated that the IgA gene is evolving in a mosaic fashion with the hinge region accumulating mutations most rapidly and the third domain at a considerably lower frequency. In spite of this pronounced accumulation of mutations, the hinge region appears to maintain the conformation of a random coil. A marked propensity to accumulate replacement over silent site changes in the coding regions was noted, as was a definite codon bias. The possibility that these two phenomena are interrelated is discussed.     

Male-Driven Evolution in Closely Related Species of the Mouse Genus Mus

Recently, other researchers have found that closely related primate species had a lower male-to-female mutation rate ratio (α) than distantly related species. To determine if this is a general phenomenon affecting other mammalian orders, eleven species or subspecies of the rodent genus Mus and two outgroup species were compared. Intron sequences from a gene in the nonrecombining region of the Y chromosome Jarid1d (Smcy) and its X chromosomal gametolog, Jarid1c (Smcx), were analyzed in a phylogenetic context. The male-to-female mutation rate ratio for all thirteen taxa is approximately 2.5, which is similar to previous estimates in more distantly related rodents. However, when branches with lengths of more than 2.5% were removed from the analysis, the male-to-female mutation rate ratio dropped to 0.9. Thus, in closely related rodents, as in closely related primates, the male-to-female mutation rate ratio is lower than expected. [Reviewing Editor: Dr. Deborah Charlesworth] An erratum to this article is available at.     

Common Mechanisms of Y Chromosome Evolution

Y chromosome evolution is characterized by the expansion of genetic inertness along the Y chromosome and changes in the chromosome structure, especially the tendency of becoming heterochromatic. It is generally assumed that the sex chromosome pair has developed from a pair of homologues. In an evolutionary process the proto-Y-chromosome, with a very short differential segment, develops in its final stage into a completely heterochromatic and to a great extends genetically eroded Y chromosome. The constraints evolving the Y chromosome have been the objects of speculation since the discovery of sex chromosomes. Several models have been suggested. We use the exceptional situation of the in Drosophila mirandato analyze the molecular process in progress involved in Y chromosome evolution. We suggest that the first steps in the switch from a euchromatic proto-Y-chromosome into a completely heterochromatic Y chromosome are driven by the accumulation of transposable elements, especially retrotransposons inserted along the evolving nonrecombining part of the Y chromosome. In this evolutionary process trapping and accumulation of retrotransposons on the proto-Y-chromosome should lead to conformational changes that are responsible for successive silencing of euchromatic genes, both intact or already mutated ones and eventually transform functionally euchromatic domains into genetically inert heterochromatin. Accumulation of further mutations, deletions, and duplications followed by the evolution and expansion of tandem repetitive sequence motifs of high copy number (satellite sequences) together with a few vital genes for male fertility will then represent the final state of the degenerated Y chromosome. This revised version was published online in July 2006 with corrections to the Cover Date.     

葱属Amerallium亚属 (石蒜科) 的系统发生与性状进化

运用贝叶斯和简约法对葱属（Allium）Amerallium亚属的核糖体DNA内转录间隔区（ITS）进行了分析,对该亚属的系统发生进行了推测。系统分析证实 Amerallium是单系的,并表明该亚属由三个隔离的地理群组成：北美Ameralliums,地中海区Ameralliums和东亚Ameralliums。性状进化的重建表明鳞茎是原始或祖先状态,根状茎和肉质增粗的根是衍生状态且在Amerallium这个亚属的类群中独立进化发生了几次。重建也表明该亚属的原始染色体基数x=7,其它染色体基数（x=8, 9, 10, 11）是由它转化而来的。在北美类群中,异基数性相当罕见,而多倍性似乎是一个相对频繁的进化事件。在地中海区类群和东亚类群中,异基数性和多倍性是染色体进化的两个主要驱动力。     

Evolution of a long-range repeat family in Chromosome 1 of the genus Mus

Copy numbers and variation of a clustered long-range repeat family on Chromosome (Chr) 1 have been studied in different species of the genus Mus. The repeat sequence was present in all, as inferred from cross-hybridization with probes derived from the Mus musculus repeat family. Copy numbers determined by dot blot hybridization were very low, from three to six per haploid genome in M. caroli, M. cervicolor, and M. cookii. These species form one branch of the phylogenetic tree in the genus Mus. In the other group of phylogenetically related species—M. spicilegus, M. spretus, M. musculus and M. macedonicus—copy numbers ranged from 6 to 1810 per haploid genome. The repeat cluster is cytogenetically visible as a fine C-band in M. macedonicus and as a C-band positive homogeneously staining region (HSR) in several populations of M. m. domesticus and M. m. musculus. When cytogenetically visible, the clusters contained from 179 to 1810 repeats. Intragenomic restriction fragment length polymorphisms (RFLPs), which reflect sequence variation among different copies of the long-range repeat family, increased with higher copy numbers. The high similarity of the RFLP pattern among genomes with C-band positive regions in Chr 1 of M. m. musculus, M. m. domesticus, and M. macedonicus points to a close evolutionary relationship of their Chr 1 repeat families.     

Chromosome Studies of Subgenus Gymnaconitum Endemic to China and Beesia (Ranunculaceae)

The paper reports chromosomal number and chromosomal morphologies of annual Aconitum gymnandrum endemic to China and Beesia calthifolia for the first time. Of the two spcies, chromosome number is same (X=8, 2n=16) and chromosome average lengths are 6.17μ , 10.73μ respectively. The longest chromosome 1, the short chromosomes 3-5, 7 and the shortest chromosome 8 are metacentrical (m), the chromosomes 2, 6 are submetacentrical (sm), and the pairs 4, 5, 8 have satellites in the karyotype of A. gymnandrum. In B. calthifolia, all of the chromosome 1-5 are the long m, the chromosomes 6, 8 are the short sm and the 7 is telocentrical (t). The pairs 3, 4, 6 have satellites. According to the comparison of karyotypes of three subgenera—subgen. Paraconitum, subgen. Aconitum and subgen. Gymnaconitum in Aconitum, the evolution trend of chromosomes is further discussed. Finally, the relationship between Aconitum and Beesia is also discussed in thispaper.     

Comparative Chromosome Painting in Six Species of Oligoryzomys (Rodentia,Sigmodontinae) and the Karyotype Evolution of the Genus

Oligoryzomys belongs to the tribe Oryzomyini, and contains about 22 species. Diploid numbers range from 2n = 44 in Oligoryzomys sp. 2 to 2n = 72 in O. utiaritensis and phylogenetic relationships are not well defined. The high morphological convergence leads to misidentification of taxonomic entities and the species are often identified by chromosomal characters. Until now, the genus has been studied only by classical cytogenetic approaches. To understand the chromosomal evolution of Oligoryzomys, we developed chromosome probes from a female of Oligoryzomys moojeni (OMO) with 2n = 70 and hybridized to other five Oligoryzomys species. The probes painted 31 segments on O. fornesi (OFO) with 2n = 62; 32 segments on O. microtis (OMI), 2n = 64; 33 segments on O. nigripes (ONI), 2n = 62 and on O. rupestris (ORU), 2n = 46; and 34 on Oligoryzomys sp. 2 (OSP), 2n = 44. OMO probes 4 and 5 showed a syntenic association in O. fornesi, O. microtis and O. nigripes and were also presented in the same pair, although disrupted, in O. rupestris and Oligoryzomys sp. 2. Concerning O. rupestris and Oligoryzomys sp. 2, species with the lowest diploid numbers of the genus, a total of 8 probes hybridized to 11 segments on the largest pair of ORU 1 and 9 probes hybridized to 12 segments on OSP 1. Also, OMO 6 painted three segments in ORU, corresponding to the proximal segment of ORU 2q, and the whole of ORU 19 and 20. In OSP, the segment corresponding to ORU 20 was homologous to OSP 1p. OMO X showed signals of hybridization in both X and Y chromosomes. Extensive chromosomal rearrangements, that could not be detected by classical cytogenetic techniques, such as pericentric inversions or repositioning of centromeres, Robertsonian rearrangements and tandem fusions/fissions, as well as gain/activation or loss/inactivation of centromeres and telomeric sequences have driven the huge genome reshuffling in these closely related species.     

The Evolution of the Y Chromosome with X-Y Recombination

A theoretical population genetic model is developed to explore the consequences of X-Y recombination in the evolution of sex chromosome polymorphism. The model incorporates one sex-determining locus and one locus subject to natural selection. Both loci have two alleles, and the rate of classical meiotic recombination between the loci is r. The alleles at the sex-determining locus specify whether the chromosome is X or Y, and the alleles at the selected locus are arbitrarily labeled A and a. Natural selection is modeled as a process of differential viabilities. The system can be expressed in terms of three recurrence equations, one for the frequency of A on the X-bearing gametes produced by females, one for each of the frequency of A on the X- and Y-bearing gametes produced by males. Several special cases are examined, including X chromosome dominance and symmetric selection. Unusual equilibria are found with the two sexes having very different allele frequencies at the selected locus. A significant finding is that the allowance of recombination results in a much greater opportunity for polymorphism of the Y chromosome. Tighter linkage results in a greater likelihood for equilibria with a large difference between the sex chromosomes in allele frequency.     

石蝴蝶属八种植物的染色体数目报道

观察了苦苣苔科石蝴蝶属(Petrocosmea)8种植物的染色体.发现它们的染色均属小型染色体,数目一致,皆为2n=34.     

The Chromosome Numbers of 10 Species in the Genus Campylotropis (Fabaceae)

This paper reports chromosome numbers of ten species and one variety of the genus Campylotropis from China (Table 1, Plate 1 ). They are C. argentea Schindl., C. bonatiana( pamp: ) Schindl., C. henryi Schindl., C. hirtella (Franch.)Schindl., C. macrocarpa(Bunge )Rehd., C. diversifolia( Hemsl. )Schindl., C. polyantha (Franch.) Schindl., C. polyantha( Franch. )Schindl. var. leiocarpa ( Pamp. ) Pet. -Stib., c. prainii ( Coll. et Hemal. ) Schindl., C. pinetorum (kurz)Schindl. ssp. velutina (Dunn)Schindl., c. trigonoclada(Franch. ) Schindl. The chromosome numbers of these ten species are all 2n= 22 or n= 11, but a few individuals in C. polyantha(Franch. )Schindl. var. leiocarpa(Pamp. )Pet. -Stib., were found aneuploid with 2n=23. The chromosome numbers of c. polyantha and C. macrocarpa have been reported by Maw-shing (1986)andLee(1972), while those of all the other species are first reported.     

A Taxonomic Study on the Genus Dryopteris Subgenus Erythrovariae (H. Ito) Fraser-Jenkins from Yunnan

In the present paper, the circum cription of the genus Dryopteris subgenus Erythrovariae (H. Ito) Fraser-Jenkins is revised, and a taxonomic study on the subgenus from Yunnan Province is carried out .The subgenus contains 2 sections, 12 species in Yunnan, of which D. yongdeensis W. M. Chu is a new species, D. championii, D. erythrosora, D. gymnosora, D. indusiata and D. integriloba are first recorded from Yunnan. The confusion between Dryopteris labordei and D. gymnosora is clarified, the former being treated as an independentspecies.     

刺膝螽属一新亚属和一新种(直翅目:螽斯总科:蛩螽科)

记述中国刺膝螽属Cyrtopsis Bey-Bienko,19621新亚属和1新种,制作了亚属及种的检索表,模式标本保存在中国科学院上海昆虫博物馆。     

Chromosome Studies in the Genus Plasmodium

SUMMARY. A study has been made of the number and morphology of the chromosomes of five species of malarial parasites as seen in living material with phase contrast microscopy. Plasmodium knowlesi , of monkeys, is essentially similar to other primate malarial parasites previously studied, having two chromosomes of unequal length. P. lophurae , from ducks, P. relictum from pigeons and sparrows, and P. floridense from a lizard all have two small chromosomes of equal size. These facts, with ether data, indicate that the genus may consist of two species complexes. P. berghei , studied in white mice and rats, has a karyotype similar to the avian and saurian malarial parasites. The suggestion is made that P. berghei , on a basis of chromosome pattern and other characteristics, is probably more closely related to the avian and saurian species of Plasmodium than to other mammalian species.     

Review of the Central American Species of the Subgenus Quedionuchus of the Genus Quedius (Col. Staphylinidae)

All species of the subgenus Quedionuchus Shp. of the genus Quedius Steph. (Staphylinidae), known to occur at present in Central America are treated. A key is given. Seven species are described as new: Q. ollin (Mexico), tecpatl (Mexico), cipactli (Guatemala), xochitl (Mexico), ehecatl (Mexico), calli (Mexico) and coatl (Mexico). Lectotypes are designated for the following 4 species: nigerrimus (Shp.), angustus (Shp.), femoralis (Shp.) and spinipes (Shp.). The species are described and illustrated, and the known data on their bionomics and geographical distribution are given.     

Co-amplification of tail-to-tail copies of MuRVY and IAPE retroviral genomes on the Mus musculus Y Chromosome

We have isolated a clone from a C57BL/6 genomic library that contains both part of the Y Chromosome-specific 8.7 kbp MuRVY genome (Hutchinson and Eicher, J. Virol. 63, 4043, 1989) and a full-length 8.3 kbp Intracisternal A Particle genome (IAPE-Y), in a tail-to-tail organization. Although IAPs are encoded by a disperse multigene family (∼1000 copies per haploid genome), we present evidence that a significant proportion of the IAP-related sequences are present on the Y Chromosome (Chr) and that a >25 kbp genomic sequence, which contains the two proviral genomes, has been amplified on the Y Chr. Two discrete amplified families of MuRVY retroviral genomes distinguishable by a polymorphic restriction site were detected, suggestive that amplification occurred in incremental stages. The presence of MuRVY-related DNA sequences, but absence of IAPE-Y-related DNA sequences in Mus spretus suggests that the IAPE-Y retrotransposition event occurred after the evolutionary divergence of the lineages leading to Mus musculus and Mus spretus, and that the amplification of MuRVY occurred independently in the two lineages. Received: 28 July 1995 / Accepted: 1 September 1995     

Phylogenetic Analysis and Karyotype Evolution in the Genus Clivia(Amaryllidaceae)

Phylogenetic relationships of five taxa of Clivia, one probablenew species plus four recognized species, and three outgroupspecies were studied using sequences of the nuclear ribosomal5S non-transcribed spacer and the internal transcribed spacer(ITS) of 45S rDNA. Analysis of the data sets separately generatedsome well-supported groupings and congruent phylogenies. Cliviaminiata and C. gardenii are closely related. ‘Robust Gardenii’,the putative new species, is a sister clade of this group. Clivianobilis is distantly related to these three taxa and C. caulescensoccupies an intermediate position between the two groups. Chromosomelocations and distribution patterns of the 5S nuclear ribosomalgene in the species of Clivia were investigated using fluorescenceinsitu hybridization (FISH). In all species, only one pair of5S rDNA signals was observed. These were located on the shortarm of chromosome 8, at the position of the interstitial C-bands.The phylogenies obtained from the DNA sequences together withthe chromosome data accumulated here and previously publishedinformation on the location of the 45S rDNA sites have beenused to postulate evolutionary trends in Clivia chromosomes.Copyright 2001 Annals of Botany Company Clivia, chromosome evolution, 45S and 5S rDNA, ITS, FISH, molecular phylogeny     

Revision of New World Species of the Shore-fly Subgenus Allotrichoma Becker of the Genus Allotrichoma with Description of the Subgenus Neotrichoma (Diptera, Ephydridae, Hecamedini)

The New World species of the subgenera Allotrichoma Becker and Neotrichoma (new subgenus) are revised, including a phylogenetic analysis of the species groups and subgenera within the genus Allotrichoma. For phylogenetic perspective and to document the monophyly of the genus Allotrichoma and its included subgenera and species groups, we also provide a cladistic analysis of genera within the tribe Hecamedini. The ingroup included seven exemplar congeners from within Allotrichoma. Outgroup sampling included exemplars of other genera within Hecamedini and from the putative sister group, Lipochaetini, and to root the analysis, we used an exemplar of the tribe Discocerinini. Analyses with successive weighting and implied weighting recovered a monophyletic Allotrichoma and indicated clades within the genus. Eight new species are described (type locality in parenthesis): Allotrichoma bifurcatum (Utah. Utah: Lake Shore (40°06.9'N, 111°41.8'W; 1370 m)), Allotrichoma dynatum (Oregon. Benton: Finley National Wildlife Refuge (44°24.6'N, 123°19.5'W)), Allotrichoma occidentale (Oregon. Lake: Lakeview (44 km E; Drake Creek; 42°11'N, 119°59.3'W)), Allotrichoma robustum (California. Kern: Kern River (35°16.1'N, 119°18.4'W)), Allotrichoma sabroskyi (New Mexico. Sandoval: La Cueva (Junction of Highways 126 and 4; 35°52'N, 106°38.4'W; 2342 m)), Allotrichoma wallowa (Oregon Baker: Goose Creek (35 km E Baker City; 44°49.2'N, 117°27.79'W; 825 m)), Allotrichoma baliops (Florida. Monroe: Key West (Willie Ward Park; 24°32.9'N, 81°47.9'W)), and Allotrichoma insulare (Dominica. Cabrits Swamp (15°35'N, 61°29'W)). Within Allotrichoma, we recognize three subgenera of which one, Neotrichoma (type species: Allotrichoma atrilabre), is newly described. All known species from the New World are described with an emphasis on structures of the male terminalia, which are fully illustrated. Detailed locality data and distribution maps for the New World species are provided. A lectotype is designated for Discocerina simplex Loew and a neotype is designated for Allotrichoma bezzii Becker. Allotrichoma filiforme Becker, Allotrichoma trispinum Becker, and Allotrichoma dahli Beschovski are reported as new synonyms of Allotrichoma simplex (Loew) and Allotrichoma yosemite Cresson is a new synonym of Allotrichoma atrilabre Cresson. We also clarify the status of previously described species, including those with Holarctic distributions. For perspective and to facilitate genus-group and species-group recognition, the tribe Hecamedini is diagnosed and a key to included genera is provided.