The interactions of Rhizobium leguminosarum biovar trifolii in nodulation of annual and perennial Trifolium spp. from diverse centres of origin

2005 ◽  
Vol 45 (3) ◽  
pp. 199 ◽  
Author(s):  
J. G. Howieson ◽  
R. J. Yates ◽  
G. W. O'Hara ◽  
M. Ryder ◽  
D. Real
Keyword(s):  
N2 Fixation ◽  
Rhizobium Leguminosarum ◽  
Subterranean Clover ◽  
South American ◽  
Equatorial Africa ◽  
Centres Of Diversity ◽  
Mediterranean Regions ◽  
North And South America ◽  
North And South ◽  
Rhizobium Leguminosarum Biovar Trifolii

The release of effective inocula for new perennial clovers into cropping zones where subterranean clover is important might compromise N2 fixation by this valuable annual clover if symbiosis between the new inoculants and subterranean clover is not optimal. To assist our understanding of the interactions between clovers and their microsymbionts, rhizobial strains and clovers from South and equatorial Africa, North and South America, and the Euro–Mediterranean regions were tested. Glasshouse-based studies of the cross-inoculation characteristics of 38 strains of Rhizobium leguminosarum bv. trifolii associated with 38 genotypes of annual and perennial Trifolium spp. from these world centres of diversity were undertaken. Less than 7.5% of the perennial clover symbioses were effective whereas 40% of associations were effective for many of the annual clover species of Euro–Mediterranean origin. There was substantial specificity within the African clovers for effective nodulation. Rhizobial strains from the South American perennial T. polymorphum or from the African clovers were unable to nodulate subterranean clover effectively. Also, 7 of the 17 strains from these regions were unable to form nodules with the less promiscuous Mediterranean annual clovers, T. glanduliferum and T. isthmocarpum. Fifty-three of about 400 cross-inoculation treatments examined, which included annual and perennial clovers, were incapable of forming nodules, while only 65 formed effective nodules. There are 2 barriers to effective nodulation: a ‘geographic’ barrier representing the broad centres of clover diversity, across which few host-strain combinations were effective; and, within each region, a significant ‘phenological’ barrier between annual and perennial species. Clovers and their rhizobia from within the Euro–Mediterranean region of diversity were more able to cross the phenological barrier than genotypes from the other regions. It appears that only the relatively promiscuous clovers, whether annual or perennial, have been commercialised to date. The data indicate that, for perennial clovers, it will be a substantial challenge to develop inocula that do not adversely affect N2 fixation by subterranean clover and other annual clovers available commercially, especially if the perennial clovers were originally from Africa or America. Some future strategies for development of inoculants for clovers are proposed.

Redescription and new records of Ontholestes brasilianus Bernhauer, 1906 (Coleoptera: Staphylinidae: Staphylininae) 

Zootaxa ◽  
2018 ◽  
Vol 4388 (1) ◽  
pp. 143
Author(s):  
VINÍCIUS COSTA-SILVA ◽  
ANGÉLICO ASENJO ◽  
ALFRED F. NEWTON ◽  
PATRICIA J. THYSSEN
Keyword(s):  
South America ◽  
New Records ◽  
South American ◽  
South American Species ◽  
Additional Species ◽  
Palearctic Species ◽  
Mistaken Identification ◽  
North And South America ◽  
First Time ◽  
North And South

The genus Ontholestes Ganglbauer includes 35 species distributed mainly in Eurasia, with a few additional species in Africa and North and South America (Herman, 2001; Yang & Zhou, 2012; Smetana & Shavrin, 2013; Rougemont, 2016). According to Asenjo et al. (2013), the South American record of the Palearctic species Ontholestes murinus (Linnaeus, 1758) for Brazil made by J. Guérin (1953) seems doubtful. Ontholestes murinus was recorded for the first time outside the Palaearctic region by Smetana (1981), from Newfoundland, in Canada, as an adventive species (e.g., Downie and Arnett, 1996; Brunke et al., 2011), but its occurrence in Brazil remains to be confirmed; if the Guérin (1953) record was based on a mistaken identification or mislabeled specimen, this would reduce the number of species distributed in this region from two to one. With respect to O. brasilianus Bernhauer, although it has been confirmed for Peru, Brazil and Argentina (Herman, 2001; Asenjo et al., 2013; Newton, 2015; Newton & Caron, 2015), no specific localities of occurrence have been reported since its description in 1906. Thus, to solve problems of misidentification with Neotropical species of this genus, in this study we redescribe Ontholestes brasilianus and provide the first illustrations of the beetle including its aedeagus and a short key for South American species. Additionally, new records from South America are listed here. 

Boron deficiency in pasture based on subterranean clover (Trifolium subterraneum L.) is linked to symbiotic malfunction

2015 ◽  
Vol 66 (11) ◽  
pp. 1197 ◽  
Author(s):  
Leo J. Hamilton ◽  
Kevin F. M. Reed ◽  
Elainne M. A. Leach ◽  
John Brockwell
Keyword(s):  
N2 Fixation ◽  
Rhizobium Leguminosarum ◽  
Root Nodule ◽  
Effective Strain ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Boron Deficiency ◽  
Initial Application ◽  
Clover Root ◽  
Clover Seed

Field and glasshouse experiments confirmed the occurrence of boron (B) deficiency in subterranean clover (Trifolium subterraneum L.) pasture in eastern Victoria. Diminished productivity was linked to the small-seededness of clover and the poor effectiveness of clover root-nodule bacteria (rhizobia, Rhizobium leguminosarum bv. trifolii). Productivity, especially of clover and clover seed, increased following applications of up to 6 kg B ha–1 (P < 0.001). The response was delayed, occurring several years after the initial application of B, unless the land was resown with fresh clover seed inoculated with an effective strain of rhizobia. B deficiency in the nodulated legume induced conditions within the plant and or its rhizobia that led to impaired nitrogen (N2) fixation. Glasshouse research indicated that populations of soil-borne rhizobia taken from B-deficient soils were poorly effective in N2 fixation and that rhizobia from soils growing subterranean clover cv. Leura were significantly less effective (P < 0.05) than rhizobia from a soil growing cv. Mt Barker. Additionally, subterranean clover seed generated in B-deficient soils was at least one-third smaller than the seed of commercial seed but responded to inoculation with effective rhizobia. This indicated that any symbiotic malfunction of clover from B-deficient soils was not due to an inability to respond to nitrogen per se. On the other hand, cv. Leura from B-deficient soils fixed significantly less N2 than commercial cv. Leura when each was inoculated with rhizobia from B-deficient soils.

Nitrogen fixation characteristics of Rhizobium surviving in soils 'equilibrated' with sewage biosolids

2001 ◽  
Vol 52 (10) ◽  
pp. 963 ◽  
Author(s):  
Kellie J. Munn ◽  
Jeffrey Evans ◽  
Phillip M. Chalk
Keyword(s):  
N2 Fixation ◽  
Soil Type ◽  
Rhizobium Leguminosarum ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Subterranean Clover ◽  
Isotope Dilution Method ◽  
Dilution Method ◽  
Symbiotic Effectiveness ◽  
Amended Soils

To determine the effects of urban sewage biosolids on the symbiotic effectiveness of Rhizobium leguminosarum bv. trifolii and N2 fixation, glasshouse and laboratory studies were carried out with several soils, biosolids, and biosolid application levels. Symbiotic effectiveness of R. l. trifolii was estimated as the dry weight or N content of seedlings of subterranean clover grown with only N2 fixation and seed N as the available nitrogen sources. The N fixed by legumes in unamended and biosolid-amended soils was determined using the 15N isotope dilution method. Six soils were represented in the experiments. Each of these was equilibrated over a period of 12 months with dried, finely ground biosolids (DWS) from the Malabar sewage treatment plant, at biosolids levels ranging from the equivalent of 60 to 240 t DWS/ha. One of the soils was also equilibrated with each of 4 other biosolids. The maximal concentration of heavy metals in soil amended with biosolids was 1026 mg/kg. The effect of biosolids on symbiotic effectiveness depended on the soil type and biosolid applications level. Thus, biosolids reduced the symbiotic effectiveness of R. l. trifolii in 2 of the 6 soils, although at different levels of biosolid. In most soil treatments N2 fixation was detected in subterranean clover, confirming the persistence of symbiotically effective rhizobia in most biosolids-amended soils. In addition, in strongly acidic soils plant N and N2 fixation increased significantly with biosolids addition, probably in response to higher soil pH, exchangeable Ca, and available P. In the treatments in which the symbiotic effectiveness of R. l. trifolii was reduced by biosolids, this was reflected in poor N2 fixation. However, symbiotic effectiveness did not correlate well with N2 fixation, probably because increases in soil nitrate at higher biosolids levels inhibited N2 fixation. Nevertheless, there were instances at 240 t DWS/ha where this was unlikely to explain the decrease in N2 fixation. It was concluded that adverse effects of biosolids on symbiotic effectiveness depend first on soil type, and then on biosolid type and application level; and the response in symbiotic effectiveness to adding biosolids to soil needs to be determined for each distinctively different site of biosolids reuse.

scholarly journals 2-Nonanone is a Critical Pheromone Component for Cerambycid Beetle Species Native to North and South America

2021 ◽  
Author(s):  
Weliton D Silva ◽  
Lawrence M Hanks ◽  
Judith A Mongold-Diers ◽  
Anna C Grommes ◽  
José Maurício S Bento ◽  
...  
Keyword(s):  
Field Testing ◽  
South American ◽  
The North ◽  
The Family ◽  
Pheromone Components ◽  
Biogeographical Regions ◽  
Cerambycid Beetles ◽  
The Individual ◽  
North And South America ◽  
North And South

Abstract An increasing body of evidence indicates that cerambycid beetles native to different continents may share pheromone components, suggesting that these compounds arose as pheromone components early in the evolution of the family. Here, we describe the identification and field testing of the pheromone blends of two species in the subfamily Cerambycinae that share 2-nonanone as an important component of their male-produced aggregation-sex pheromones, the South American Stizocera consobrina Gounelle (tribe Elaphidiini) and the North American Heterachthes quadrimaculatus Haldeman (tribe Neoibidionini). Along with 2-nonanone, males of S. consobrina also produce 1-(1H-pyrrol-2-yl)-1,2-propanedione, whereas males of H. quadrimaculatus produce 10-methyldodecanol. Field bioassays conducted in Brazil (targeting S. consobrina) and Illinois (targeting H. quadrimaculatus) demonstrated that adults of both species were attracted only by the blends of both their pheromone components, and not to the individual components. The use of the pyrrole as a critical component for the former species is further evidence that this compound is a common pheromone structure among cerambycines in different biogeographical regions of the world.

scholarly journals Ancient mitochondrial DNA reveals convergent evolution of giant short-faced bears (Tremarctinae) in North and South America

2016 ◽  
Vol 12 (4) ◽  
pp. 20160062 ◽  
Author(s):  
Kieren J. Mitchell ◽  
Sarah C. Bray ◽  
Pere Bover ◽  
Leopoldo Soibelzon ◽  
Blaine W. Schubert ◽  
...  
Keyword(s):  
South America ◽  
North American ◽  
Convergent Evolution ◽  
Phylogenetic Analyses ◽  
Early Pleistocene ◽  
South American ◽  
The North ◽  
Molecular Phylogenetic ◽  
North And South America ◽  
North And South

The Tremarctinae are a subfamily of bears endemic to the New World, including two of the largest terrestrial mammalian carnivores that have ever lived: the giant, short-faced bears Arctodus simus from North America and Arctotherium angustidens from South America (greater than or equal to 1000 kg). Arctotherium angustidens became extinct during the Early Pleistocene, whereas Arctodus simus went extinct at the very end of the Pleistocene. The only living tremarctine is the spectacled bear ( Tremarctos ornatus ), a largely herbivorous bear that is today only found in South America. The relationships among the spectacled bears ( Tremarctos ), South American short-faced bears ( Arctotherium ) and North American short-faced bears ( Arctodus ) remain uncertain. In this study, we sequenced a mitochondrial genome from an Arctotherium femur preserved in a Chilean cave. Our molecular phylogenetic analyses revealed that the South American short-faced bears were more closely related to the extant South American spectacled bear than to the North American short-faced bears. This result suggests striking convergent evolution of giant forms in the two groups of short-faced bears ( Arctodus and Arctotherium ), potentially as an adaptation to dominate competition for megafaunal carcasses.

Floral Biology and Reproduction in Poa (Poeae: Gramineae)

1995 ◽  
Vol 43 (6) ◽  
pp. 577 ◽  
Author(s):  
AM Anton ◽  
HE Connor
Keyword(s):  
North America ◽  
South America ◽  
New World ◽  
Floral Biology ◽  
South American ◽  
Western North America ◽  
Dioecious Species ◽  
Indeterminate Form ◽  
North And South America ◽  
North And South

Flowers in the cosmopolitan genus Poa L. are predominantly hermaphrodite but many departures from this sex form occur in the New World. Dioecism is primarily a South American breeding system with about three times as many dioecious species as in the rest of the world. Gynomonoecism is a Central and South American trait heavily represented in Andean Peru and Bolivia. This zone of gynomonoecism separates dioecism in North and South America. Gynodioecism, a convenient evolutionary position on the pathway to dioecism, is relatively infrequent and in North America is of indeterminate form in several taxa. Apomixis has long been recognised in European Pea; in western North America, apospory has invaded dioecious species and generated populations of pistillate plants. In Peru and Bolivia, several taxa are composed exclusively of plants with pistillate flowers, but these have arisen from gynomonoecious progenitors. Poa is of Eurasian origin and migrated to North America and thence to South America. Sex-form kinds and frequencies are in stark contrast in the two parts of the continent, but are explicable in evolutionary terms. The selection pressures generating the deviations from hermaphroditism and their timing are unknown.

scholarly journals Puma genomes from North and South America provide insights into the genomic consequences of inbreeding

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Nedda F. Saremi ◽  
Megan A. Supple ◽  
Ashley Byrne ◽  
James A. Cahill ◽  
Luiz Lehmann Coutinho ◽  
...  
Keyword(s):  
North American ◽  
Landscape Connectivity ◽  
Western Hemisphere ◽  
Central American ◽  
South American ◽  
Isolated Populations ◽  
Genome Wide ◽  
North And South America ◽  
North And South ◽  
Close Inbreeding

Abstract Pumas are the most widely distributed felid in the Western Hemisphere. Increasingly, however, human persecution and habitat loss are isolating puma populations. To explore the genomic consequences of this isolation, we assemble a draft puma genome and a geographically broad panel of resequenced individuals. We estimate that the lineage leading to present-day North American pumas diverged from South American lineages 300–100 thousand years ago. We find signatures of close inbreeding in geographically isolated North American populations, but also that tracts of homozygosity are rarely shared among these populations, suggesting that assisted gene flow would restore local genetic diversity. The genome of a Florida panther descended from translocated Central American individuals has long tracts of homozygosity despite recent outbreeding. This suggests that while translocations may introduce diversity, sustaining diversity in small and isolated populations will require either repeated translocations or restoration of landscape connectivity. Our approach provides a framework for genome-wide analyses that can be applied to the management of similarly small and isolated populations.

scholarly journals Disproportionate extinction of South American mammals drove the asymmetry of the Great American Biotic Interchange

2020 ◽  
Vol 117 (42) ◽  
pp. 26281-26287 ◽  
Author(s):  
Juan D. Carrillo ◽  
Søren Faurby ◽  
Daniele Silvestro ◽  
Alexander Zizka ◽  
Carlos Jaramillo ◽  
...  
Keyword(s):  
South America ◽  
North American ◽  
Biotic Interactions ◽  
South American ◽  
Dispersal Rate ◽  
Great American Biotic Interchange ◽  
Drastic Increase ◽  
The Asymmetry ◽  
North And South America ◽  
North And South

The interchange between the previously disconnected faunas of North and South America was a massive experiment in biological invasion. A major gap in our understanding of this invasion is why there was a drastic increase in the proportion of mammals of North American origin found in South America. Four nonmutually exclusive mechanisms may explain this asymmetry: 1) Higher dispersal rate of North American mammals toward the south, 2) higher origination of North American immigrants in South America, 3) higher extinction of mammals with South American origin, and 4) similar dispersal rate but a larger pool of native taxa in North versus South America. We test among these mechanisms by analyzing ∼20,000 fossil occurrences with Bayesian methods to infer dispersal and diversification rates and taxonomic selectivity of immigrants. We find no differences in the dispersal and origination rates of immigrants. In contrast, native South American mammals show higher extinction. We also find that two clades with North American origin (Carnivora and Artiodactyla) had significantly more immigrants in South America than other clades. Altogether, the asymmetry of the interchange was not due to higher origination of immigrants in South America as previously suggested, but resulted from higher extinction of native taxa in southern South America. These results from one of the greatest biological invasions highlight how biogeographic processes and biotic interactions can shape continental diversity.

A low oxygen tolerant East Pacific flat clam (Posidonotis semiplicata) from the Lower Jurassic of the Canadian Cordillera

1996 ◽  
Vol 33 (7) ◽  
pp. 993-1006 ◽  
Author(s):  
M. Aberhan ◽  
J. Pálfy
Keyword(s):  
Lower Jurassic ◽  
South American ◽  
Benthic Organisms ◽  
Geographic Isolation ◽  
Low Oxygen ◽  
High Concentration ◽  
Mode Of Life ◽  
North And South America ◽  
North And South ◽  
Comprehensive Study

Flat clams represent a loosely defined group of thin-shelled, flat-valved bivalves. Their distribution and high concentration in some, especially Mesozoic, rocks have attracted interest, and several contrasting paleoecologic interpretations have been proposed to explain their occurrence. We present a comprehensive study of Posidonotis semiplicata (Hyatt), an Early Jurassic flat clam common in western North and South America. Posidonotis symmetrica (Hyatt), Posidonotis balteata (Crickmay), and Posidonotis cancellata (Leanza) are interpreted as subjective junior synonyms. In North America, P. semiplicata occurs in the upper Sinemurian to lower Toarcian of several Cordilleran allochthonous terranes. The South American record is restricted to upper Pliensbachian to lower Toarcian occurrences, suggesting that the species originated in the northeast Pacific in late Sinemurian time and spread to the southeast Pacific by the late Pliensbachian. The closely related Posidonotis dainellii (Losacco), sporadically known from the Tethys, is likely derived from P. semiplicata via migration through the Hispanic Corridor and subsequent geographic isolation. The functional morphology of P. semiplicata suggests an early ontogenic byssal attachment followed by a reclining mode of life with adaptation to soft substrates. The species is commonly found forming shell pavements in dark mudrocks with no, or very few, other benthic organisms. It provides an example of an epibenthic bivalve that favoured low-energy, dysaerobic environments, a niche preferentially exploited by flat clams.

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