Intraspecific chromosome variation in Cebus apella (cebidae,platyrrhini): The chromosomes of the yellow breasted capuchin Cebus apella xanthosternos wied, 1820

Chromosome studies in six wild-caught specimens of Cebus apella xanthosternos showed a distinctive chromosome pair number 11 that made it possible to distinguish this subspecies from other Cebus apella. The characteristic chromosome pair had intercalar heterochromatin unlike the “standard” chromosome type of Cebus apella and other species of the same genus, in which this chromosome pair shows a large, terminal, heterochromatic block. A comparison at the chromosomal level between different Cebus apella populations suggests that chromosome 11 in Cebus apella xanthosternos is a derived chromosome that has probably become fixed in this subspecies, either by selection or by drift in a small isolated population.     

RAPD variation in Mediterranean turtle <Emphasis Type="Italic">Testudo graeca</Emphasis> L. (Testudinidae)

The polymerase chain reaction with arbitrary primers (RAPD-PCR) was used to study intraspecific variation in Mediterranean turtle Testudo graeca, which is represented by the Dagestan (T. g. pallasi) and Nikolskii (T. g. nikolskii) subspecies in Russia. To study the phylogenetic relationships, the RAPD variation was also compared in two other T. graeca subspecies (T. g. ibera and T. g. terrestris), two closely related Testudo species (T. kleinmanni and T. marginata), and Central Asian turtle Agrionemys horsfieldii. Parameters of RAPD variation showed that the sample from different geographical regions of Dagestan was more polymorphic and heterogeneous than that from Central Asia. The two samples differed in the mean number of RAPD fragments N (48.76 vs. 40.40), number of polymorphic fragments P (78.7 vs. 32.3), and within-group similarity index APS (0.607 vs. 0.784). In T. g. pallasi, no significant difference in N, P, or APS was observed between samples from different localities of Dagestan or between groups of turtles with four- or five-clawed forelegs. A dendrogram of genetic similarity between the species and subspecies under study contained two clusters, one comprising all A. horsfieldii individuals and the other, all turtles of the genus Testudo. In the latter, T. marginata and T. kleinmanni showed higher similarity to each other than to T. graeca. The four T. graeca subspecies clustered separately from each other with a high reliability, T. g. nikolskii and T. g ibera (Turkey) being more similar to each other than to T. g. terrestris or T. g. pallasi. The possible causes of the presence of four claws on forelegs of turtles from Dagestan and the relationships among members of the genus Testudo were discussed.Translated from Genetika, Vol. 40, No. 12, 2004, pp. 1628–1636.Original Russian Text Copyright © 2004 by Semyenova, Korsunenko, Vasilyev, Pereschkolnik, Mazanaeva, Bannikova, Ryskov.     

Variability of Storage Proteins and Esterase Isozymes in Vicia Sativa Subspecies

The relationships among 20 samples belonging to 6 subspecies of Vicia sativa based on the variability of seed storage proteins and esterase isozyme electrophoretic patterns was discussed in relation to variation in their morphology and chromosome characters. Electrophoretic protein profiles of different accessions of the same subspecies showed identical (e.g. macrocarpa and cordata) or similar (e.g. amphicarpa) patterns, confirming the stablity of seed storage proteins within these subspecies. However, considerable variation of protein patterns were observed within accessions of both nigra and sativa subspecies, which could be correlated to different geographical origins. Esterase pattern revealed a sharp distinction for each subspecies according to the number and loci of allelic bands. The dendrogram delimited the subspecies incisa and sativa as two separate groups, while the other subspecies were grouped together in another group.     

Chromosomal distinction between the red-faced and black-faced black spider monkeys (Ateles paniscus paniscus and A. p. chamek)

The two subspecies of the black spider monkey, Ateles paniscus paniscus and A. p. chamek, can be distinguished by their chromosome number, 2n = 32 in the former and 2n = 34 in the latter. This difference most probably is the result of a tandem fusion between chromosomes 4 and 13 of the original Ateles karyotype (2n = 34) to form a unique metacentric chromosome in A. p. paniscus. Further differences between the subspecies concern the presence of additional interstial or terminal C-bands in chromosomes 3, 5, and 12 of A. p. paniscus. A third difference is that chromosome 12 is metacentric in A. p. paniscus but is submetacentric in A. p. chamek. A. p. chamek shows dimorphisms caused by pericentric inversions in pairs 1, 5, 6, and 7 as well as in the Y chromosome. Since the dimorphisms in pairs 5 and 7 are only found in homozygous condition, they may indicate the existence of geographic variation within this subspecies. Differences in external characteristics possibly reflect these chromosomal difference. The necessity to lend A. p. paniscus full specific status should be considered, since karyologically this is the most distinct one of all forms of Ateles. In captive breeding A. p. paniscus should evidently be treated as a separate population, as hybridization with A. p. chamek may result in offspring with reduced fertility. The intra-subspecific karyological variation in A. p. chamek and its possible consequences for taxonomy and captive breeding require further investigation.     

The origin of an unusual sex chromosome constitution in <Emphasis Type="Italic">Acomys</Emphasis> sp. (Rodentia,Muridae) from Tanzania

This paper describes a case which presents an evident variation from the “standard” XX/XY sex chromosomal constitution in a rodent, Acomys sp. This species known to be found in three localities of East Africa has only recently been separated from A. spinosissimus, its closest relative. In our study, five specimens of Acomys sp. and eight specimens of A. spinosissimus were live-trapped in five localities. Comparisons between the two taxa assed by G- banding show a complete homology in the chromosomal shape and banding pattern for 29 pairs of chromosomes corresponding to the complete autosomal set of A. spinosissimus. However, while all the A. spinosissimus analysed have 2n = 60 and a XY-XX system, in Acomys sp. males and females constitute mosaics for sex chromosomes in the bone marrow cells. Females (2n = 59, 60) have an excess (97%) of aneuploid cells with one single giant X chromosome, and males (2n = 60, 61) show X0/XY cells occurring in somatic tissues and XY cells in the germinal lineage. In addition, an odd heterochromatic submetacentric chromosome was identified in all the cells examined in two males and a female of Acomys sp. Since this chromosome was not related to sex determination and it is not present in all the analysed specimens, it can be considered as a B chromosome. Finally, the in situ fluorescence hybridisation (FISH) with telomeric probes showed a very intense interstitial telomeric signal (ITS) at the medial part on the long heterochromatic arm of the X chromosome. This could be due to recent chromosomal rearrangement.     

Comparative cytogenetics and heterochromatic patterns in two species of the genus Acanthostracion (Ostraciidae: Tetraodontiformes)

Some groups of fish, such as those belonging to the Order Tetraodontiformes, may differ significantly in the amount and location of heterochromatin in the chromosomes. There is a marked variation in DNA content of more than seven-fold among the families of this Order. However, the karyoevolutionary mechanisms responsible for this variation are essentially unknown. The largest genomic contents are present in species of the family Ostraciidae (2.20–2.60 pg). The present study cytogenetically characterized two species of the family Ostraciidae, Acanthostracion polygonius and A. quadricornis, using conventional staining, C-bandings, Ag-NOR, CMA₃/DAPI, AluI, PstI, EcoRI, TaqI and HinfI restriction enzymes (REs) and double FISH with 18S and 5S rDNA probes. The karyotypes of both species showed 2n = 52 acrocentric chromosomes (FN = 52; chromosome arms) and pronounced conserved structural characteristics. A significant heterochromatic content was observed equilocally distributed in pericentromeric position in all the chromosome pairs. This condition is unusual in relation to the karyotypes of other families of Tetraodontiformes and probability is the cause of the higher DNA content in Ostraciidae. Given the role played by repetitive sequences in the genomic reorganization of this Order, it is suggested that the conspicuous heterochromatic blocks, present in the same chromosomal position and with apparently similar composition, may have arisen or undergo evolutionary changes in concert providing clues about the chromosomal mechanisms which led to extensive variation in genomic content of different Tetraodontiformes families.     

高山物种栗色鼠尾草(Salvia castanea Diels)访花昆虫多样性与传粉行为变化

唇形科鼠尾草属是世界性分布、物种多样性丰富的大类群,具有独特的传粉模式和多样化的生态类型及繁殖策略,以往对鼠尾草属的花结构和雄蕊杠杆的生态功能、雄蕊杠杆机制对传粉者空间变异的进化响应和表型选择等方面已有较深入的研究,但至今对分布于不同区系代表性物种的传粉者组成、访花行为和繁育系统特征仍知之甚少。对分布于喜马拉雅东段至横断山高海拔地区栗色鼠尾草的传粉生态、交配系统和繁殖特性进行了研究,分析了2014年至2016年的年际间、2014年晴天和阴雨天的传粉者组成和传粉行为变化,探讨了这些变化对繁殖成功的影响。研究结果表明：3年共发现栗色鼠尾草有9种访花昆虫,传粉者组成及其行为变化较为明显。2014年有桔尾熊蜂Bombus friseanus、灰熊蜂B.grahami、圣熊蜂B.religiosus和中华蜜蜂Apis cerana 4种有效传昆虫,2015年仅有桔尾熊蜂是有效传粉者,而2016年的有效传粉昆虫改变为灰熊蜂和圣熊蜂。栗色鼠尾草的盗蜜现象较为普遍,主要盗蜜昆虫为灰熊蜂和桔尾熊蜂。桔尾熊蜂访花行为的年际变化较大,受天气条件的影响明显,同时其有效传粉行为可能显著影响了灰熊蜂的盗蜜行为。栗色鼠尾草的繁育系统为专性异交,主要依靠传粉者进行授粉,缺少传粉者时低程度的主动自花授粉可为其提供繁殖保障,且没有花粉限制和近交衰退。研究揭示了在高海拔地区,多变的天气条件可能显著影响着鼠尾草属植物的传粉者种类组成、访花行为和传粉效率,进而影响植物的繁殖成效和种群稳定。有效传粉频率是保证栗色鼠尾草较高自然结实率的主要因素,在一定程度上,盗蜜强度对繁殖成功具有中性的影响。本研究结果为阐明高山鼠尾草物种的繁殖如何受气候环境变化的影响,以及保证繁殖成功的可能策略奠定基础。     

Mismatch of morphological and molecular identifications in native and invasive subspecies of Codium fragile (Bryopsidophyceae,Chlorophyta)

Several subspecies are defined within Codium fragile, including the invasive C. fragile ssp. fragile, first reported in New Zealand in 1973. An endemic subspecies, C. fragile ssp. novae‐zelandiae, is also found throughout New Zealand. The two subspecies exhibit morphological and molecular variation, although these have never been evaluated together. We compared variation between subspecies at locations in Auckland, identifying subspecies using rps3‐rpl16 DNA sequence data, and assessing gross morphological differences, anatomical utricle characters and morphometrics. The taxonomic utility of the morphometric data sets was assessed by linear discriminant analysis. Utricle characters and measurements varied within individual thalli and between different preservation methods. The phenotypes of both subspecies were highly variable and influenced by environment. Accurate subspecies delimitation using morphological data was not possible; the discriminant analyses performed no better than chance for all combinations of the morphological data. Specimens from New Zealand, Canada, Australia and Ireland were sequenced using both the rps3‐rpl16 and tufA plastid markers. The tufA elongation factor was shown to be a good candidate for differentiating subspecies of C. fragile. This marker is twice the length of the rps3‐rpl16 spacer, shows greater variation between ssp. fragile and novae‐zelandiae, and is less prone to sequencing error. A simple restriction enzyme digest of the tufA amplicon can distinguish ssp. fragile and ssp. novae‐zelandiae. Our study expands the known range of the ssp. fragile in New Zealand, including the first record of this subspecies from the west coast of Auckland, and points to a need to re‐evaluate morphological and molecular criteria for subspecies currently defined within C. fragile.     

Early replication banding in <Emphasis Type="Italic">Leporinus</Emphasis> species (Osteichthyes,Characiformes) bearing differentiated sex chromosomes (ZW)

There are few examples of differentiated sex chromosomes in fishes. In the genus Leporinus, seven species present a highly differentiated ZW system, derived from heterochromatinization process. Cytogenetic analyses carried out in three of these fish species, Leporinus obtusidens, L. elongatus and L. reinhardti, through RBG-banding, showed late replication bands, coincident with heterochromatic regions in both Z and W chromosomes. A similar interstitial early replication segment was observed in the complex heterochromatic region along the Wq arms in the three species, which might correspond to a pseudoautosomal segment (SD, sex determining locus). Asynchrony related to the replication pattern among different Z chromosomes was not observed. When the identification of nuclear organizer regions by silver nitrate was performed over chromosomal preparations previously exposed to 5-bromo-2′-deoxyuridine (BrdU), remarkable positive signals at interstitial and telomeric position were observed on the q arms of W chromosomes in the species L. elongatus and L. reinhardti. The absence of 18S ribosomal RNA gene loci in this region, formerly demonstrated by FISH, indicates that this argentophilic behavior is putatively due to heterochromatin decondensation caused by BrdU incorporation, favoring such Ag+ reaction. Early and late replication bands were also observed in the heterochromatic portions of Z and W chromosomes, indicating that euchromatic and heterochromatic regions are interspersed. The present data suggest a significant level of heterochromatic complexity in the sex chromosomes of each species. On the other hand, the replication pattern shared by them supports a monophyletic origin.     

Mainland colonization by island lizards

Aim We investigate biogeographic relationships within the lizard genus Anolis Daudin, 1802 to test the hypothesis that the mainland (Central and South American) Norops‐clade species descended from a West Indian Anolis ancestor. Previous hypotheses have suggested that close island relatives of mainland Norops species (the Cuban Anolis sagrei and Jamaican A. grahami series) represent over‐water dispersal from a mainland ancestor. These previous hypotheses predict that the A. sagrei and A. grahami series should be phylogenetically nested within a Norops clade whose ancestral geography traces to the mainland. If Norops is West Indian in origin, then West Indian species should span the deepest phylogenetic divergences within the Norops clade. Location Central and South America and West Indian islands. Methods The phylogenetic relationships of Anolis lizards are reconstructed from aligned DNA sequences using both parsimony and Bayesian approaches. Hypotheses are tested in two ways: (1) by reconstructing the ancestral geographic location for the Norops clade using Pagel & Lutzoni's (2002) Bayesian approach, and (2) by testing alternative topological arrangements via Wilcoxon Signed‐Ranks tests ( Templeton, 1983 ) and Shimodaira–Hasegawa tests ( Shimodaira & Hasegawa, 1999 ). Results Our evidence supports an origin of mainland Norops anoles from a West Indian ancestor. A West Indian ancestor to the Norops clade is statistically supported, and alternatives to the biogeographic pattern [Cuban (Jamaican, Mainland)] are statistically rejected by Shimodaira–Hasegawa tests, although not by Wilcoxon Signed‐Ranks tests. Main conclusions Our data support the hypothesis of a West Indian origin for mainland Norops. This result contradicts previous hypotheses and suggests that island forms may be an important source for mainland biodiversity.     

Phylogeography of the white-throated dipper Cinclus cinclus in Europe

Cytochrome b gene sequence variation (902 bp) was used to investigate phylogenetic relationships and genetic differentiation among the four subspecies of European white-throated dipper Cinclus cinclus (Aves; Cinclidae). Six cytochrome b haplotypes were revealed, the most common one (H 13–4) was shared by all seven populations studied. Central European C. c. aquaticus was genetically more diverse than the other subspecies (although not significantly so, due to small sample sizes), whereas our sample of the nominate subspecies from the French Pyrenees showed no haplotype variation. Pairwise comparisons of the four subspecies showed significant genetic differentiation between the taxa except for a lack of differentiation of C. c. hibernicus versus C. c. aquaticus and C. c. cinclus. The genetic structure and the phylogeographic pattern were not related to the geographic distribution of the four subspecies thus disputing the validity of the current infraspecific taxonomy of C. cinclus at least in Europe.Béatrice Lauga and Christine Cagnon contributed equally to this paper.     

Cytological localization of the genes for the four classes of ribosomal RNA (25S, 18S, 5.8S and 5S) in polytene chromosomes of Phaseolus coccineus

Homologous tritiated 25S, 18S and 5.8S rRNAs were used separately for in situ hybridization to the polytene chromosomes of the embryo suspensor cells of Phaseolus coccineus. Hybridization occurred at the same chromosomal sites which were labeled in previous in situ hybridization experiments with 25+18S rRNAs in the same material (Avanzi et al., 1972), namely: nucleolus organizing system (satellite, nucleolar constriction and organizer) of chromosome pairs I (S₁) and V (S₂), proximal heterochromatic segment of the long arm of chromosome pair I, and terminal heterochromatic segment of chromosome pair II. Competition hybridization experiments confirmed for P. coccineus the high sequence homology between 25S and 18S rRNA already known for other plants.Homologous ¹²⁵I-5S rRNA was found to hybridize to three sites in the polytene chromosomes of P. cocdneus: the proximal heterochromatic segment in the long arm of chromosome pair I (which also bears the sequences complementary to 25S, 18S and 5.8S RNAs), most of the proximal heterochromatic segment plus a small portion of adjoining euchromatin in the long arm of chromosome pair VI and the large intercalary heterochromatic segment in the same chromosome pair. Simultaneous labeling of the two 5S RNA sites in chromosome VI was quite rare (3%), the rule being labelling of one site to the exclusion of the other, with a labeling frequency of 43.7% and 53.3% for sites no. 1 and no. 2 respectively. These results are interpreted as being due to differential hybridizability of chromosomal sites such as described in other materials.     

Chromosome differences in Peromyscus maniculatus populations at different altitudes in Colorado

Mice of the genus Peromyscus all have 48 chromosomes. Yet the appearance of the 48 chromosomes is highly variable from species to species (Hsu & Arrighi, 1966, 1968, 1971; Pathak et al., 1973) and even in different populations of the same species (Sparkes & Arakaki, 1966; Ohno et al., 1966; Hsu & Arrighi, 1968; Arakaki et al. 1970; Te & Dawson, 1971; Bradshaw & Hsu, 1972; Murray & Kitchin, 1976). The evolutionary significance of this variation and the mechanisms for its initiation and maintenance have been of interest for quite a few years. However, it was not until the sophisticated chromosome banding techniques became available that mammalian cytogeneticists were able to begin to study the chromosome variation of Peromyscus in some detail. The use of C-banding led Hsu & Arrighi (1971) to the finding that the short arms of chromosomes in three different species of Peromyscus contained constitutive heterochromatin. These results suggested that the variations in the number of acrocentric chromosomes in Peromyscus might be a result of different amounts of heterochromatin. Later studies (Duffey, 1972; Waterbury, 1972; and Pathak et al., 1973) were also consistent with this hypothesis.However, it was soon discovered that not all chromosomal differences among Peromyscus populations are due to heterochromatin changes. Studies by Arighi et al. (1976) and Murray & Kitchin (1976) showed that some chromosomal differences between species and subspecies of Peromyscus are due to pericentric inversions. Thus, it appears that both inversions and the addition of heterochromatin are involved in the evolution of the karyotype of Peromyscus.The purpose of our study was to investigate the chromosomes of Peromyscus maniculatus in different populations in Colorado (U.S.A.) and to test for relationships involving an altitudinal gradient. In the first part of this study, orcein stained chromosomes from three subspecies of mice sampled at nine different altitudes were examined for karyotype variability. In the second part of the study, karyotypes of two subspecies (P. m. rufinus and P. m. luteus), representing high and low altitude populations were examined with Q banding to determine the mechanisms responsible for chromosomal differences.     

In situ methylation of insect chromosomes with methylase HpaII

A method of in situ DNA methylation with the prokaryotic methylase HpaII has been developed on fixed mitotic and meiotic chromosomes of the insect species Baetica ustulata. Incorporation of methyl groups into the chromosomal DNA is revealed by autoradiography using a labelled substrate and by its ability to prevent endonuclease digestion. The method allows direct visualization of clusters of methylatable CCGG sites. The distribution of these clusters in the chromosome complement of Baetica shows two separate domains of heterochromatic DNA which differ in their methylation patterns. Each is distributed at equivalent locations in both homologous and nonhomologous chromosomes. The existence of two compartments, one methylated and the other unmethylated, in the heterochromatic DNA could be interpreted as a remnant of the ancestral echinoderm-like pattern of methylation.     

Genetic variation in Ecballium elaterium (Cucurbitaceae): Breeding system and geographic distribution

Dioecy, the separation of sexes, has arisen independently many times in the course of angiosperm evolution. Avoidance of inbreeding is clearly involved in the evolution of dioecy, and as a consequence we predict that dioecious populations should maintain higher levels of genetic variation than closely related nondioecious populations. We tested that prediction by comparing allozymic variation in two closely related taxa, the monoecious and dioecious subspecies of the Mediterranean cucurbit, Ecballium elaterium. Thirteen polymorphic loci were screened for seeds sampled from 10 monoecious and 13 dioecious populations spanning the geographic ranges of the subspecies in Spain. The dioecious subspecies showed strikingly greater allelic diversity and heterozygosity than the monoecious subspecies. A hierarchical F-statistic analysis clearly demonstrated considerable genetic variation within populations for the dioecious populations, whereas for the monoecious populations almost all genetic variation resulted from differences among populations. The general pattern of homozygosity within monoecious populations suggests that they are highly inbred. In order to assess historical influences on current patterns of genetic variation, we conducted a genetic-distance analysis. The observed relationship between genetic distance and geographic distance between populations supports the hypothesis that the subspecies' current allopatric distributions on the Iberian Peninsula are the result of separate waves of colonization from the north (monoecious) and south (dioecious).     

Embryonic stages and eye‐specific gene expression of the local cyprinoid fish Anabarilius grahami in Fuxian Lake,China

Anabarilius grahami is a cyprinoid fish endemic to Fuxian Lake, Yunnan, China. In this study, a comprehensive staging series of A. grahami was produced. The embryonic development of A. grahami was divided into six main periods: zygote period, cleavage period, blastula period, gastrula period, segmentation period and hatching period. Its embryonic development is essentially similar to that of zebrafish Danio rerio but relatively slower. The expression patterns of A. grahami sox2, pax6a, six3a and rx2 genes were also cloned and checked during eye development. The four genes showed similar expression patterns to their D. rerio homologues, suggesting the evolutionary conservation of the regulatory network of eye development.     

Characterization of polymorphic microsatellite loci in the tropical ant‐plant Leonardoxa africana (Fabaceae: Caesalpinioideae)

Ten microsatellite loci were isolated from the African ant‐plant Leonardoxa africana (Fabaceae: Caesalpinioideae). They differentiate the two most divergent subspecies of this polytypic complex, L. a. africana and L. a. gracilicaulis, showing promise for the study of gene flow. In each of these two subspecies, high levels of within‐population variation were observed, with a number of alleles ranging from one to 10 in ssp. africana and from one to 7 in ssp. gracilicaulis, and heterozygosity from 0 to 0.933 in ssp. africana and to 0.867 in ssp. gracilicaulis. All loci amplified successfully in the two other subspecies of L. africana.     

The karyotypes of the thorny catfishes <Emphasis Type="Italic">Wertheimeria maculata</Emphasis> Steindachner, 1877 and <Emphasis Type="Italic">Hassar wilderi</Emphasis> Kindle, 1895 (Siluriformes: Doradidae) and their relevance in doradids chromosomal evolution

We studied the karyotypes of two doradids, the rare and endangered Wertheimeria maculata and a derived Amazonian species, Hassar wilderi. Cytogenetic characterization was assessed using conventional staining (Giemsa), C-banding, and NOR banding. Both species had 2n = 58 chromosomes but differed in their chromosome formulae, 24 m + 14sm + 8st + 12a for W. maculata and 32 m + 16sm + 10st for H. wilderi. In W. maculata heterochromatin was mainly telomeric, and three chromosomes had a fully heterochromatic arm; in H. wilderi heterochromatin was also predominantly telomeric and evident in many more chromosomes. Hassar wilderi also presented one pair of homologues with a fully heterochromatic arm. In both species, nucleolar organizer regions were restricted to one pair of subtelocentric chromosomes. Assuming a basal position for W. maculata, we hypothesized that underlying conserved diploid and NOR-bearing chromosome numbers, chromosomal evolution in doradids has involved pericentric inversions and an increase of heterochromatic blocks.