Cytotaxonomic study of theVicia cracca complex 1. Czechoslovak taxa

Three races ofVicia cracca L. have been found on the territory of Czechoslovakia, two with the chromosome number 2n=14 and one with 2n=28. Diploid races seem to be more primitive and are less widely distributed. They occur mostly in the primary communities while the tetraploid race is very plastic in the ecological respect and is common both in primary and secondary communities. These races are characterized by some morphological and ecological features. As far as the vertical distribution is concerned, one of the diploid races and the tetraploid occur mostly in the lowland and in the colline zone, the second diploid race has a mountain character. The related tetraploid speciesVicia oreophila ?ertová, with the chromosome number 2n=28 is distributed at similar altitudes.     

mtDNA perspective of chromosomal diversification and hybridization in Peters' tent-making bat (Uroderma bilobatum: Phyllostomidae)

We compared sequence variation in the complete mitochondrial cytochrome-b gene with chromosomal and geographical variation for specimens of Peters' tent-making bat (Uroderma bilobatum). Three different chromosomal races have been described in this species: a 2n = 42 race from South America east of the Andes, a 2n = 44 from NW Central America and 2n = 38 from the rest of Central America and NW South America. The deepest nodes in the tree were found within the South American race (42 race), which is consistent with a longer history of this race. Average distance among races ranged from 2.5 to 2.9%, with the highest amount of intraracial variation found within the 2n = 42 race (1.7%), intermediate values within the 2n = 38 race (0.9%) and lowest within the 2n = 44 race (0.5%). Variation among chromosomal races accounted for over 55% of molecular variance, whereas variation among populations within races accounted for 6%. The 2n = 38 and 2n = 44 races hybridize in the coastal lowlands of Honduras, near the Gulf of Fonseca. Introgression between these two races is low (two introgressed individuals in 45 examined). Clinal variation across the hybrid zone for the cytochrome-b of U. bilobatum, is similar to clinal variation reported for chromosomes and isozymes of this species. Mismatch distribution analyses suggests that geographical isolation and karyological changes have interplayed in a synergistic fashion. Fixation of the alternative chromosomal rearrangements in geographical isolation and secondary contact is the most likely mechanism accounting for the hybrid zone between the 2n = 38 and 2n = 44 races. If a molecular clock is assumed, with rates ranging from 2.3 to 5.0% per million years, then isolation between these races occurred within the last million years, implying a relatively recent origin of the extant diversity in Uroderma bilobatum. None the less, the three chromosomal races probably represent three different biological species.     

Polyploidy in Ambrosia dumosa (Compositae: Ambrosieae)

Ambrosia dumosa (A. Gray ex Torr.) Payne is one of the most abundant shrubs of the Sonoran Desert. Allopatric and sympatric populations of this species frequently exhibit distinctive morphological features, particularly with regard to leaf-segment width, but also in blooming time and ecology. Chromosome numbers ofn = 18, 36, and 54 were frequently encountered in our preliminary investigations ofA. dumosa. Fifty-six chromosome number determinations have now accumulated for this taxon, and these additional counts confirm the existence of three major chromosome races withinA. dumosa. Diploids generally occur throughout the range of the species; hexaploids tend to be confined to the deserts of California; and tetraploids occur through most of the range of the species, with the exception of southern Baja California and Owens Valley, California. External morphology was found to be correlated with chromosome number only locally, but even in many local areas, morphological intergradation occurs between different chromosome races. It is therefore considered impractical to attempt a formal taxonomy which would recognize these chromosomal races.     

Changing status of the parasites of potato tuber mothPhthorimaea operculella [Lepidoptera: Gelechiidae] in Australia

Three introduced parasites ofPhthorimaea operculella (Zeller) are now widespread, and a fourth established in a limited area, in Australia.Apanteles subandinus Blanchard, which occurs from Tasmania to Queensland, is the most effective species and the outstanding parasite in Victoria. The extent of parasitism and the status of the various parasites were monitored from the time of their release until 1971. In many areas whereCopidosoma koehleri Blanchard was the only parasite found in 1966, a substantial increase in parasitism was recorded in subsequent years, following the liberation of other species. In the 1969–70 season there was an explosive increase inOrgilus lepidus Muesebeck, which became the dominant species in some coastal areas of New South Wales, displacingA. subandinus. Its change of status to a dominant position was associated with a change of sex ratio from 1.6 ♀: 1♂ to 1.0 ♀: 1 ♂.     

A new chromosomal race of the common shrew <Emphasis Type="Italic">Sorex araneus</Emphasis> (Lipotyphla,Mammalia) found in Russia

Karyotyping of the common shrews Sorex araneus from the poorly studied region of the Northwest of Russia revealed the belonging of individuals to two chromosomal races, Lemi and St. Petersburg. The Lemi race, previously known only from Finland, was discovered for the first time on the territory of Russia and thus replenished the list of S. araneus chromosomal races that are distributed within the Russian part of the species range (27 races out of 74 known in the whole species range at the moment). The studied individuals showed a high level of chromosomal polymorphism, caused by Rb translocations.     

Oogenesis and the Chromosomes of the Parthenogenic Root-knot Nematode Meloidogyne incognita

220 populations of Meloidogyne incognita and related forms from 46 countries reproduced by mitotic parthenogenesis (apomixis). Determination of somatic chromosome numbers from oogonia and oocytes revealed the existence of a predominant, possibly triploid race A with 3n = 40 to 46 and a rare, diploid race B with 2n = 32 to 36 chromosomes. There is no correlation between cytological races and the four recognized host races of this species. The characteristic behavior of prophase I chromosomes of maturing oocytes, which results in a prolonged prophase stage, is a unifying feature of all forms of M. incognita and supports monophyletic evolution, distinct from that of other Meloidogyne species. Extensive chromosomal polymorphism detected among populations can be helpful in elucidating the cytological pathway of evolution of the species.     

Effect of blast infection on the photosynthetic activity of rice seedlings

Photosynthesis was affected considerably when the cultivars Zenith, Lacrosse, Usen and Co. 13 belonging to indica and japonica groups of rice were inoculated with physiological races IC₁₃ and ID₁ ofPyricularia oryzae Cav. The 21-day seedlings after inoculation withP. oryzae and uninoculated control were exposed to¹⁴CO₂ under natural sunlight (190 Wm^-2). The extent of reduction in photosynthetic rate in the cultivars varied on inoculation with different races ofP. oryzae used, the reduction being more apparent with race ID₁.     

Chromosomal localization and genomic organization of cloned repetitive DNA fragments in mosquitoes (Diptera: Culicidae)

The chromosomal localization and genomic organization of three cloned repetitive DNA fragments (viz., H-76, H-61, and H-19) isolated from theAedes albopictus genome have been examined inAe. albopictus and six otherAedes species:Ae. aegypti, Ae. seatoi, Ae. flavopictus, Ae. polynesiensis, Ae. alcasidi andAe. katherinensis. The results fromin situ and Southern hybridization analyses show that the sequences homologous to cloned repetitive DNA fragments are dispersed throughout the genome in each species. The sequences homologous to these cloned repetitive DNA fragments are also found inHaemagogus equinus, Tripteroides bambusa andAnopheles quadrimaculatus and are dispersed in their genomes. Data indicate divergence in the amount and the structural organization of sequences homologous to these cloned fragments among mosquito species.     

The systematics of autopolyploidy in Epilobium latifolium (Onagraceae)

Diploid (2n = 36) plants ofEpilobium latifolium L. have been found in Alaska and the western Cordillera of North America, and tetraploids in Iceland, western Greenland, and southeastern Quebec. Study of the morphology of these chromosome races revealed a character, the number of pores in the pollen grains, by which they could be distinguished with an average probability of 75%. Tetraploids ofE. latifolium tend to have high percentages of 4-pored pollen, while the diploids usually have only 3-pored pollen. On this basis, the ranges of the races were extrapolated from herbarium material. Detailed comparisons of eight other features of the presumptive diploids and tetraploids showed no significant difference between them. The races appear to form worldwide, allopatric, ecogeographic phases. A high level (57.4%) of quadrivalent formation observed during tetraploid meiosis, and other considerations, indicate that the tetraploids arose by autopolyploidy. The recommendation is made that the races not be given formal taxonomic recognition.     

EXTREME KARYOTYPIC VARIATION IN A MUS MUSCULUS DOMESTICUS HYBRID ZONE: THE TOBACCO MOUSE STORY REVISITED

The Robertsonian fusion is a common chromosomal mutation among mammal species and is especially prevalent in the West European house mouse, Mus musculus domesticus. More than 40 races of the house mouse exist in Europe, including the famous “tobacco mouse” (Poschiavo race) of Val Poschiavo, Switzerland. Documented here is the discovery of an extreme case of karyotypic variation in the neighboring Upper Valtellina, Italy. In a 20-km stretch of the valley, 32 karyotypes were observed, including five chromosomal races and 27 hybrid types. One previously unknown race is reported, the “Mid Valtellina” race, with a diploid number of 2n = 24 and the Robertsonian fusions Rb(1.3), Rb(4.6), Rb(5.15), Rb(7.18), Rb(8.12), Rb(9.14), Rb(11.13), and Rb(16.17). The Poschiavo race (2n = 26), Upper Valtellina race (2n = 24), Lower Valtellina race (2n = 22) and all-acrocentric race (2n = 40) were also present. The races form a patchy distribution, which we term a “mottled hybrid zone.” Geographical position, isolation, extinction, recolonization, and selection against hybrids are all believed to be instrumental in the origin and evolution of this complex system. Previous studies of house mice from Upper Valtellina indicated that two of the races in the valley (the Upper Valtellina and Poschiavo races) may have speciated in the village of Migiondo. We discuss the possibility that there may have been a reinforcement event in this village.     

Comparative chromosomal analysis of populations of phytophilous chironomidae Glyptotendipes glaucus (Mg.) from Chernobyl affected territory

The karyopools of the phytophilous chiromomid species of Glyptotendipes glaucus (Mg.) were studied. Chironomids originated from a number of reservoirs located in the Novozybkovsky raion of the Bryansk region, which was affected by the Chernobyl radioactive release, and two reservoirs located in the Saratov region. Differences in the inversion spectrum and frequencies, both among Bryansk and between Bryansk and Saratov populations, were found. There were no new inversions in the Novozybkovsky populations; however, structurally small rearrangements in long chromosomes were noted. Typical abnormalities included mosaicism of the chromosome morphotypes in cells of the same saline gland, which was especially distinctive in the larvae from the forbidden zone; decondensation of the telomere regions of chromosomes; and mosaic asynapsis of the chromosome IV homologs (up to complete disjunction). Also, several larvae were polyploids. Other species of Glyptotendipes inhabiting the Novozybkovsky reservoirs were represented by the single species of G. paripes (near the Korchy settlement). The karyotypes of its several larvae were represented by an unorganized chromosomal substance. The other Glyptotendipes species seem to have lower adaptive abilities under the conditions in question and were eliminated from precatastrophe biotopes, while G. glaucus succeeded in adaptating to the new environment.     

A new species of Senna (Caesalpiniaceae) from coastal northern Bahia,Brazil

Irwin, Howard S. (Clark Garden, 193 I. U. Willets Road, Albertson, NY 11507) and Rupert C. Barneby (New York Botanical Garden, Bronx, NY 10458-9980). A new species of Senna (Caesalpiniaceae) from coastal northern Bahia, Brazil. Brittonia 37: 192–194. 1985. - Senna (sect. Chamaefistula ser. Laxiflorae) phlebadenia, closely akin to S. australis, but the only known species of the genus with secondary veins of leaflets excurrent into a marginal nectary, is described and illustrated from two collections from the coastal plain of Bahia northeast of Salvador.     

Use of synteny to identify candidate genes underlying QTL controlling stomatal traits in faba bean (Vicia faba L.)

Key message

We have identified QTLs for stomatal characteristics on chromosome II of faba bean by applying SNPs derived from M. truncatula , and have identified candidate genes within these QTLs using synteny between the two species.

Abstract

Faba bean (Vicia faba L.) is a valuable food and feed crop worldwide, but drought often limits its production, and its genome is large and poorly mapped. No information is available on the effects of genomic regions and genes on drought adaptation characters such as stomatal characteristics in this species, but the synteny between the sequenced model legume, Medicago truncatula, and faba bean can be used to identify candidate genes. A mapping population of 211 F₅ recombinant inbred lines (Mélodie/2 × ILB 938/2) were phenotyped to identify quantitative trait loci (QTL) affecting stomatal morphology and function, along with seed weight, under well-watered conditions in a climate-controlled glasshouse in 2013 and 2014. Canopy temperature (CT) was evaluated in 2013 under water-deficit (CTd). In total, 188 polymorphic single nucleotide polymorphisms (SNPs), developed from M. truncatula genome data, were assigned to nine linkage groups that covered ~928 cM of the faba bean genome with an average inter-marker distance of 5.8 cM. 15 putative QTLs were detected, of which eight (affecting stomatal density, length and conductance and CT) co-located on chromosome II, in the vicinity of a possible candidate gene—a receptor-like protein kinase found in the syntenic interval of M. truncatula chromosome IV. A ribose-phosphate pyrophosphokinase from M. truncatula chromosome V, postulated as a possible candidate gene for the QTL for CTd, was found some distance away in the same chromosome. These results demonstrate that genomic information from M. truncatula can successfully be translated to the faba bean genome.     

Comparative analysis of bacterial community-metagenomics in coastal Gulf of Mexico sediment microcosms following exposure to Macondo oil (MC252)

The indigenous bacterial communities in sediment microcosms from Dauphin Island (DI), Petit Bois Island (PB) and Perdido Pass (PP) of the coastal Gulf of Mexico were compared following treatment with Macondo oil (MC252) using pyrosequencing and culture-based approaches. After quality-based trimming, 28,991 partial 16S rRNA sequence reads were analyzed by rarefaction, confirming that analyses of bacterial communities were saturated with respect to species diversity. Changes in the relative abundances of Proteobacteria, Bacteroidetes and Firmicutes played an important role in structuring bacterial communities in oil-treated sediments. Proteobacteria were dominant in oil-treated samples, whereas Firmicutes and Bacteroidetes were either the second or the third most abundant taxa. Tenericutes, members of which are known for oil biodegradation, were detected shortly after treatment, and continued to increase in DI and PP sediments. Multivariate statistical analyses (ADONIS) revealed significant dissimilarity of bacterial communities between oil-treated and untreated samples and among locations. In addition, a similarity percentage analysis showed the contribution of each species to the contrast between untreated and oil-treated samples. PCR amplification using DNA from pure cultures of Exiguobacterium,  Pseudoalteromonas,  Halomonas and Dyadobacter, isolated from oil-treated microcosm sediments, produced amplicons similar to polycyclic aromatic hydrocarbon-degrading genes. In the context of the 2010 Macondo blowout, the results from our study demonstrated that the indigenous bacterial communities in coastal Gulf of Mexico sediment microcosms responded to the MC252 oil with altered community structure and species composition. The rapid proliferation of hydrocarbonoclastic bacteria suggests their involvement in the degradation of the spilt oil in the Gulf of Mexico ecosystem.     

Seasonal density,distribution and interactions of predatory and scavenger arthropods in accumulating poultry wastes in coastal and interior Southern California

Seasonal predatory and scavenger arthropod densities were studied at interior and coastal southern California poultry ranches. Though some seasonal population clumping occurred with some species, the distribution of predators and scavengers was fairly uniform within each ranch. Correlation analyses of key predators in theHisteridae, Staphylinidae, Hydrophylidae andDermaptera with the potential hosts,Musca domestica L.,Tinea fuscipunctella Haworth, andFannia spp. suggested that predator activity was seasonally influenced. Possible periodic avoidance of a particular host's habitat was detected as significant negative correlations. The data tend to support the importance of different species of predators in different seasons and the need for natural enemy complexes rather than single species for biological control.     

Cytotaxonomy ofCalliphoridae (Diptera)

A modification of the general system of classification ofCalliphoridae is proposed in this report. Information about the chromosome complements of about 90 species is provided including references to the earlier literature on chromosomes of this family. With one exception all species studied by us or by earlier investigators have 2n=12. The total complement length of 556 complements from 83 species averaged 66.4 μ. Most species have a short heteromorphic sex pair but the size and morphology vary considerably and one species,Hemipyrellia fernandica, seems to have a quadrivalent sex-chromosome complex in a 2n=14 complement. The autosomal pairs vary in both length and arm ratios between the species but seem to be more stable than the sex chromosomes. Only minor variations were found between different collections of the same species except for two collections ofCalliphora croceipalpis. Although presently available data on the chromosomes of Diptera species suggest that increases in total complement length accompany evolutionary progress, no such general trends were obvious in either the total complement lengths or chromosome morphology, either within or between the tribes ofCalliphoridae. Thus the karyotypical reorganizations in the family have apparently not been directly associated with changes in the general morphological features of the adults which may have responded in these respects more extensively to genetic mutations.     

Chromosome numbers,polyploidy, and hybridization in castilleja (scrophulariaceae ) of the Great Basin and Rocky Mountains

Chromosome numbers are reported for 190 collections ofCastilleja of the Great Basin-Rocky Mountains and adjacent regions in western North America. Polyploidy has played a major role in evolu tion of this genus. Of the 35 taxa represented, 14 are exclusively diploid (n =12). The remaining 21 taxa exhibit polyploidy: eight are tetraploid only, two are octopIoid only, while 11 of the more wide-ranging species have two or more levels of polyploidy. BothC. rhexifolia andC. sulphured have diploid, tetraploid, and octoploid races while the widespreadC. miniata has four (2x, 4x, 8x, and 10x). Where appropriate, the role of polyploidy and hybridization inCastilleja evolution and their relevance to taxonomy are discussed for individual species.