Speciation Of Forms Research Articles

Persistence and fate of chlortetracycline in the aquatic environment under sub-tropical conditions: generation and dissipation of metabolites

The persistence of chlortetracycline in the aquatic environment, including the generation and dissipation of its metabolites, were investigated over a period of 90 days using microcosm experiments, with a view to establishing the metabolites generated and their persistence under conditions closely resembling the actual aquatic environment in terms of chemical and microbial composition. The concentrations of chlortetracycline and its metabolites were monitored in the water phase as well as the sediment phase. Data are presented showing that the degradation of chlortetracycline in each phase conforms to a triphasic linear rate law, confirming the existence of three speciation forms in each phase, attributed to one free dissolved form, and two colloidal particle adsorbed forms. Data are also presented showing that the two adsorbed forms are the most persistent, with life-times of 204.1 and 20.3 days respectively in the water phase, and 215.1 and 19.8 days respectively in the sediment phase. Life-times of 5.01 and 3.7 days respectively were obtained for the free dissolved forms in the water phase and sediment phase respectively. Data are further presented showing that of the several metabolites of chlortetracycline reported previously, only 4-epi-chlortetracycline and iso-chlortetracycline could be detected, and that these two degradation products undergo microbial mineralization without transformation to other intermediate degradation products in significant or detectable amounts.

Effect of Selenium Form and Salicylic Acid on the Accumulation of Selenium Speciation Forms in Hydroponically Grown Lettuce

Selenium (Se) uptake by plants depends on its form and salicylic acid (SA) can increase the efficiency of plant biofortification in Se. This study investigated the effects of selenite (Na2SeO3) and selenomethionine (SeMet) applied individually or together with SA on a total content of Se, Se speciation forms, yield and content of sugars and ascorbic acid of lettuce, as well as activity of selenocysteine methyltransferase (smt) and methionine methyltransferase (mmt) genes of the Se metabolic pathway. Lettuce was grown in the nutrient film technique (NFT) system. Se and SA were used at doses of 0.5 and 10.0 mg dm−3 of the nutrient solution, respectively. The treatments were: 1. control, 2. Na2SeO3, 3. Na2SeO3 + SA, 4. SeMet, 5. SeMet + SA, 6. SA. Se was accumulated more in the roots than the leaves. SeMet was more effective in biofortification than Na2SeO3. SA enhanced Se uptake, especially organic Se. Plants supplied with SeMet alone or SeMet + SA accumulated in their leaves mainly SeMet and methylselenocysteine (MeSeCys), while those treated with Na2SeO3 or Na2SeO3 + SA accumulated MeSeCys and selenite (SeO3−2). The roots showed no expression of smt, while the expression of two mmt genes was independent of either Se or SA. The leaves of plants supplied with Na2SeO3 demonstrated the strongest expression of mmt and smt.

Efficient Removal of Toxic mMetal Ions (Pb(II) and Hg(II) Ions in Single Component Systems by Adsorption on Romanian Clay Material

In this study, a local natural clay material was used for the efficient removal of Pb(II)ions and Hg(II) ions from aqueous media, in batch system. The adsorptive potential of clay material was testes at different initial solution pH, adsorbent dosage, contact time and initial heavy metal ions concentration and room temperature (20  2C). The highest adsorption efficiency of clay material was found at initial pH of 7.0 in case of Pb(II) ions, and 2.0 in case of Hg(II) ions, while the adsorbent dosage had the same value (4 g/L) for both metal ions. The adsorption equilibrium is very fast and was reach within 10 min. The modelling of experimental data showed that the adsorption processes followed the Freundlich isotherm model and pseudo-second order kinetic model. Detailed analysis of the experimental data indicate that the retention of Pb(II) and Hg(II) ions from aqueous solution on clay materials involves two processes, one of adsorption and the other of precipitation, whose succession depends on the speciation form of the metal ion in aqueous solution. However, the high adsorption capacity and short contact time are important characteristics which suggest the potential use of this clay material in environmental remediation processes.

New insight studies of the secondary phase formation under repository conditions

ABSTRACTIn a deep geological repository (DGR) scenario, uranium oxidized in aqueous systems will be stabilized as UO22+ (hexavalent uranium), as a consequence of tetravalent uranium oxidation by radiolytic byproducts. Uranyl cationic species (UO22+) in different speciation forms are expected to be found at the whole pH range conditions. The importance of UO22+ lies in its potential incorporation of trace radioelements onto secondary uranyl phases. In view of the difficulty of U chemistry in natural groundwater, it is necessary to improve speciation assessment techniques so as to understand chemical processes. Raman spectroscopy has been shown as a powerful tool to analyze the speciation of various actinyl (UO22+,NpO2+ and PuO22+) and to determine the distribution of those elements which are more likely to be stable in a near-field groundwater environment. Therefore, the aim of this work is to follow UO22+ changes as a consequence of γ radiation in aqueous media under DGR conditions, and to understand the behavior of UO22+ as a function of aqueous media, which help to understand and predict the potential precipitation of the solid phases formed. In this work, the use of Raman spectroscopy adapted to the empirical analysis of different nuclear applications for initial uranium concentrations 0.04M at ambient atmosphere is shown, i.e. as monitoring tool for UO22+ precipitation as a function of pH, studying UO2(NO3)2·6H2O stability in aqueous solutions representative of groundwater, in particular at ionic strength I = 0.02 – 0.4 M and pH from 7 to 13.2; and to evaluate the effect of γ radiation fields. At 10−4-10-3 M of radiolytically formed H2O2 concentration, the amount of uranium in solution decreased, as a results of secondary phases precipitation. The results obtained will be useful to the performance assessment studies of the Spent Nuclear Fuel (SNF) stored in DGRs. The work performed provides a partial picture of secondary phase formations, as a result of corrosion of SNF in a DGR.

Absorption spectra of pyruvic acid in water: insights from calculations for small hydrates and comparison to experiment.

Pyruvic acid is abundant in the atmosphere and in seawater, being a decay product of living organisms. Although very small in size (10 atoms), pyruvic acid exhibits conformational complexity in the gas phase and in solution, which is reflected in the UV spectrum. The gas phase UV spectrum of pyruvic acid differs from the spectrum of pyruvic acid in water. The main atmospherically relevant absorption peak in the gas phase is blue shifted by about 0.43 eV (40 nm difference in the peak location) in water. The origin of the blue shift has not been established thus far. This paper aims at a microscopic understanding of the absorption spectrum of pyruvic acid in aqueous media by a combined experimental and theoretical approach. 1H NMR experiments were performed to reveal the contribution of the different conformers in solution as a function of pH. Computationally, hydrates of sizes up to 5 water molecules using two different species of pyruvic acid, the neutral acid and the anionic form were considered. Vertical excitation energies using the ADC(2) method (algebraic-diagrammatic construction through second order) of these structures provide insights into the blue shift of the atmospherically relevant absorption peak. Additionally, molecular dynamics simulation on MP2 (Møller-Plesset perturbation theory) ground state of small clusters of pyruvic acid with four water molecules were calculated and used in computing the vertical excitation spectrum along the dynamics. This is found to describe very accurately the experimental spectrum. Overall, the results show that small hydrate models including the roles of both neutral and deprotonated speciated forms provide a good quantitative description and a microscopic interpretation of the experimental spectrum of pyruvic acid in aqueous solution.

Occurrence of antibiotics residues in hospital wastewater, wastewater treatment plant, and in surface water in Nairobi County, Kenya.

The occurrence of 17 antibiotics belonging to sulfonamides, β-lactams, macrolides and aminoglycosides classes, and trimethoprim in raw hospital wastewater, wastewater treatment plant (WWTP), and surface water was determined. Residual antibiotics were quantified by LC/MS/MS. Residues of antibiotics in hospital wastewater were 3-10 times higher than that detected in WWTP and surface water. Trimethoprim, spectinomycin, ampicillin, and oxacillin were detected in all the sampled water. Sulfamethoxazole was detected at the highest concentration of 20.6, 7.8, and 6.8 μg L-1 in hospital wastewater, WWTP and in surface water, respectively. Other detected sulfonamides were sulfamethazine, sulfadiazine, and sulfanilamide at a concentration range of 0.4-15.7 μg L-1. Detected trimethoprim ranged from 0.4-6.6 μg L-1, the rest of the detected antibiotics were up to 1.0 μg L-1. The speciation of the sulfonamides at pH values relevant to sampled water was evaluated by use of pKa values. These compounds existed largely as anionic and neutral species indicating high mobility as these speciation forms are less sorbed in environmental matrices. Continuous monitoring of antibiotics residues in wastewater, surface water, and other environmental matrices is very important due to their adverse health and environmental effects. The information is useful in designing strategies for antibiotics pollution control and also in policy formulation.

Dispersal out of Wallacea spurs diversification of Pteropus flying foxes, the world's largest bats (Mammalia: Chiroptera).

Islands provide opportunities for isolation and speciation. Many landmasses in the Indo-Australian Archipelago (IAA) are oceanic islands, and founder-event speciation is expected to be the predominant form of speciation of volant taxa on these islands. We studied the biogeographic history of flying foxes, a group with many endemic species and a predilection for islands, to test this hypothesis and infer the biogeographic origin of the group. Australasia, Indo-Australian Archipelago, Madagascar, Pacific Islands. Pteropus (Pteropodidae). To infer the biogeographic history of Pteropus, we sequenced up to 6169 bp of genetic data from 10 markers and reconstructed a multilocus species tree of 34 currently recognized Pteropus species and subspecies with 3 Acerodon outgroups using BEAST and subsequently estimated ancestral areas using models implemented in BioGeoBEARS. Species-level resolution was occasionally low because of slow rates of molecular evolution and/or recent divergences. Older divergences, however, were more strongly supported and allow the evolutionary history of the group to be inferred. The genus diverged in Wallacea from its common ancestor with Acerodon; founder-event speciation out of Wallacea was a common inference. Pteropus species in Micronesia and the western Indian Ocean were also inferred to result from founder-event speciation. Dispersal between regions of the IAA and the islands found therein fostered diversification of Pteropus throughout the IAA and beyond. Dispersal in Pteropus is far higher than in most other volant taxa studied to date, highlighting the importance of inter-island movement in the biogeographic history of this large clade of large bats.

Cd uptake by Phytolacca americana L. promoted by cornstalk biochar amendments in Cd-contaminated soil

Cadmium (Cd) contamination is the most extensive pollution in China farmland. A greenhouse pot trial was conducted to investigate the effects of cornstalk biochar on Cd accumulation by Phytolacca americana L. (pokeweed) in Cd-contaminated soil. The Cd concentration increased in leaves, shoots, and roots of plants amended with 5% biochar by 79%, 113%, and 32%, respectively, compared with the pokeweed without biochar. The Cd availability, soil Cd speciation, soil fertility, root biomass, and Cd chemical forms in root were investigated to explore the mechanism by which Cd uptake increased in presence of biochar. The extractability of Cd by DTPA decreased in presence of biochar by 30% compared with that of soil without biochar. The increases occurred with dose of biochar increased in available phosphorus, labile organic carbon, and C/N atom ratio. Although, the dry weight of the aboveground part of the pokeweed decreased by 38.5%, however, the weight of roots increased by 20.8%. Root biomass and microbial activity reached maximum in the treatment that recieved 5% biochar. Cd forms extracted by NaCl and acetic acid (HAc) were predominant in root. When 5% biochar applied to soil, HAc-extracted Cd took up maximum of the increase in root.

Combined exposure to lead, cadmium, mercury, and arsenic and kidney health in adolescents age 12–19 in NHANES 2009–2014

BackgroundOccupational and environmental exposures to toxic metals are established risk factors for the development of hypertension and kidney disease in adults. There is some evidence of developmental metal nephrotoxicity in children and from animal studies; however, to our knowledge no previous studies have examined associations between co-exposure to nephrotoxic environmental metals and children's kidney health. ObjectiveThe objective of this study was to assess the association between co-exposure to lead (Pb), cadmium (Cd), mercury (Hg), and arsenic (As), measured in urine and blood, and kidney parameters in US adolescents. MethodsWe performed a cross-sectional analysis of a subsample of 2709 children aged 12–19 participating in the National Health and Nutrition Examination Survey (NHANES) between 2009 and 2014. We analyzed urine levels of 4 nephrotoxic metals selected a priori (As, Cd, Pb and Hg), Umix, and 3 nephrotoxic metals in blood (Cd, Pb, and Hg), Bmix, using a weighted quantile sum (WQS) approach. We applied WQS regression to analyze the association of Bmix and Umix with estimated glomerular filtration rate (eGFR), serum uric acid (SUA), urine albumin, blood urea nitrogen (BUN), and systolic blood pressure (SBP), adjusting for sex, race/ethnicity, age, head of household's education level, height, BMI, serum cotinine, and NHANES cohort year. Umix and urine albumin models were also adjusted for urine creatinine, and Bmix models were also adjusted for fish consumption. Subanalyses included stratification by sex and an arsenic-only model including six speciated forms of As measured in urine. ResultsIn WQS regression models, each decile increase of Umix was associated with 1.6% (95% CI: 0.5, 2.8) higher BUN, 1.4% (95% CI: 0.7, 2.0) higher eGFR, and 7.6% (95% CI: 2.4, 13.1) higher urine albumin. The association between Umix and BUN was primarily driven by As (72%), while the association with eGFR was driven by Hg (61%), and Cd (17%), and the association with urine albumin was driven by Cd (37%), Hg (33%), and Pb (25%). There was no significant relationship between Umix and SUA or SBP. In WQS models using the combined blood metals, Bmix, each decile increase of Bmix was associated with 0.6% (95% CI: 0.0, 1.3) higher SUA; this association was driven by Pb (43%), Hg (33%), and Cd (24%) and was marginally significant (p = 0.05). No associations were observed between Bmix and urine albumin, eGFR, BUN, or SBP. ConclusionsThe findings suggest metals including As, Pb, Hg, Cd and their combinations may affect renal parameters, although potential reverse causation cannot be ruled out due to the cross-sectional study design. Implications of early life low-level exposure to multiple metals on kidney function may have far-reaching consequences later in life in the development of hypertension, kidney disease, and renal dysfunction. Longitudinal studies should further evaluate these relationships.

MODIFICATION OF HUMIC SUBSTANCES FOR DEVELOPMENT OF MATERIALS FOR ENVIRONMENTAL TECHNOLOGIES

Humic substances are high molecular weight refractory polycationites formed during decay of living organic matter and through biosynthesis of low molecular weight organic substances (metabolites or decay products of living organisms). Presence of many functional groups in the structure of humic substances determines their ability to interact with metal ions forming stable complexes and influencing metal ion speciation in the environment and mobility, behaviour and speciation forms in the environment. Presently humic substances are a product of industrial scale and quantities in amounts of hundreds of tons are produced. The aim of this study is to analyse derivatization possibilities of humic substances. To achieve this aim derivatization of humic substances using acylation (at first introduction of acetylgroups, but also changing length acyl chains are considered) are used. Also alkylation is used. Mild oxidation can help to obtain modified products with reduced molecular weight. Another approach includes introduction of new functional groups and structures. To achieve this aim, conjugates with short peptides, amines and sugar derivatives using coupling with water-soluble carbodiimides are obtained. As basic characteristics elemental analysis as well as functional analysis have been used, supported with Fourier transform infrared (FTIR), 13C nuclear magnetic resonance spectrometry and other methods. Derivatives of humic substances containing sulpho, amino, and hydroxylgroups and thiolgroups were synthesized and their properties were analyzed in respect to their their elemental composition; functional group content changes in spectral characteristics. The derivatives of humic substances showed significant differences in the number and in ability to interact with the metal ions, which were reflected in their complexation properties towards metal ions. FTIR spectra gave evidence of the presence of metal ions, strongly bound and protected in inner sphere complexes. The obtained derivatives of humic substances can be used for remediation of environment contaminated with heavy metal ions.

The importance of reactive oxygen species on the aqueous phototransformation of sulfonamide antibiotics: kinetics, pathways, and comparisons with direct photolysis

Sulfonamide antibiotics (SAs) are increasingly detected as aquatic contaminants and exist as different dissociated species depending on the pH of the water. Their removal in sunlit surface waters is governed by photochemical transformation. Here we report a detailed examination of the hydroxyl radical (•OH) and singlet oxygen (1O2) mediated photooxidation of nine SAs: sulfamethoxazole, sulfisoxazole, sulfamethizole, sulfathiazole, sulfamethazine, sulfamerazine, sulfadiazine, sulfachloropyridazine and sulfadimethoxine. Both •OH and 1O2 oxidation kinetics varied depending on the dominant protonated states of the SA in question (H2SAs+, HSAs0 and SAs−) as a function of pH. Based on competition kinetic experiments and matrix deconvolution calculations, HSAs0 or SAs− (pH ∼5–8) were observed to be more highly reactive towards •OH, while SAs− (pH ∼8) react the fastest with 1O2 for most of the SAs tested. Using the empirically derived rates of reaction for the speciated forms at different pHs, the environmental half-lives were determined using typical 1O2 and •OH concentrations observed in the environment. This approach suggests that photochemical 1O2 oxidation contributes more than •OH oxidation and direct photolysis to the overall phototransformation of SAs in sunlit waters. Based on the identification of key photointermediates using tandem mass spectrometry, 1O2 oxidation generally occurred at the amino moiety on the molecule, whereas •OH reaction experienced multi-site hydroxylation. Both these reactions preserve the basic parent structure of the compounds and raise concerns that the routes of phototransformation give rise to intermediates with similar antimicrobial potency as the parent SAs. We therefore recommend that these phototransformation pathways are included in risk assessments concerning the presence and fate of SAs in waste and surface waters.

Speciation Theory of Carcinogenesis Explains Karyotypic Individuality and Long Latencies of Cancers.

It has been known for over 100 years that cancers have individual karyotypes and arise only years to decades after initiating carcinogens. However, there is still no coherent theory to explain these definitive characteristics of cancer. The prevailing mutation theory holds that cancers are late because the primary cell must accumulate 3–8 causative mutations to become carcinogenic and that mutations, which induce chromosomal instability (CIN), generate the individual karyotypes of cancers. However, since there is still no proven set of mutations that transforms a normal to a cancer cell, we have recently advanced the theory that carcinogenesis is a form of speciation. This theory predicts carcinogens initiate cancer by inducing aneuploidy, which automatically unbalances thousands of genes and thus catalyzes chain-reactions of progressive aneuploidizations. Over time, these aneuploidizations have two endpoints, either non-viable karyotypes or very rarely karyotypes of new autonomous and immortal cancers. Cancer karyotypes are immortalized despite destabilizing congenital aneuploidy by clonal selections for autonomy—similar to those of conventional species. This theory predicts that the very low probability of converting the karyotype of a normal cell to that of a new autonomous cancer species by random aneuploidizations is the reason for the karyotypic individuality of new cancers and for the long latencies from carcinogens to cancers. In testing this theory, we observed: (1) Addition of mutagenic and non-mutagenic carcinogens to normal human and rat cells generated progressive aneuploidizations months before neoplastic transformation. (2) Sub-cloning of a neoplastic rat clone revealed heritable individual karyotypes, rather than the non-heritable karyotypes predicted by the CIN theory. (3) Analyses of neoplastic and preneoplastic karyotypes unexpectedly identified karyotypes with sets of 3–12 new marker chromosomes without detectable intermediates, consistent with single-step origins. We conclude that the speciation theory explains logically the long latencies from carcinogen exposure and the individuality of cancers. In addition, the theory supports the single-step origins of cancers, because karyotypic autonomy is all-or-nothing. Accordingly, we propose that preneoplastic aneuploidy and clonal neoplastic karyotypes provide more reliable therapeutic indications than current analyses of thousands of mutations.

The Heavy Metals Speciations in Bottom Sediments of Vyshny Volochek Reservoir

The water ecosystem of the Vyshny Volochek Reservoir is characterized based on the study of the distribution of heavy metals speciations in the solid phase and pore waters of bottom sediments. Using the sequential extraction procedure, it is shown that Mn is mainly present in exchangeable and carbonate-bound forms; significant roles for Fe, Zn, Pb, and Co are played by forms that are bound to iron and manganese hydroxides and Cu and Ni are mainly bound to organic matter. Thermodynamic calculations have established the prevailing share of the following forms in pore waters: free ions for Zn, Ni, Co, and Cd, carbonate complexes for Pb, and fulvic complexes for Cu. It has been revealed that the speciation forms of heavy metals in bottom sediments depend on the lithological features and content of organic matter in sediments.

HEAVY METAL SPECIATION IN BOTTOM SEDIMENTS OF THE VYSHNEVOLOTSKY RESERVOIR

The study of heavy metal speciation in bottom sediments of the Vyshnevolotsky water reservoir is presented in this paper. Sequential selective procedure was used to determine the heavy metal speciation in bottom sediments and thermodynamic calculation — to determine ones in interstitial water. It has been shown that Mn are mainly presented in exchangeable and carbonate forms; for Fe, Zn, Pb и Co the forms are related to iron and manganese hydroxides is played an important role; and Cu and Ni are mainly associated with organic matter. In interstitial waters the main forms of heavy metal speciation are free ions for Zn, Ni, Co and Cd, carbonate complexes for Pb, fulvate complexes for Cu. Effects of particle size and organic matter content in sediments on distribution of mobile and potentially mobile forms of toxic elements have been revealed.

Researching of tritium speciation in soils of “Balapan” site

Speciation of tritium (3Н) in soils from the “Balapan” site in Semipalatinsk are presented in this study. Three interrelated objects were chosen for further study: “Atomic” lake, the Shagan River and an external reservoir. The main speciation forms of 3Н in soil were: 3Н in surface-adsorbed water, 3Н in interlayer water, hydroxylic 3Н, organically bound 3Н and crystalline-bound 3Н.Results will allow an estimation of contamination mechanism to be made, and will also allow the potential for migration and bioavailability of 3Н to be assessed.

The absorption of iodine from 5-iodosalicylic acid by hydroponically grown lettuce

Abstract The aim of the study was to determine the effect of various doses of 5-iodosalicylic acid (5I-SA; organoiodine compound) on the growth, chemical composition, and efficiency of iodine biofortification of lettuce cultivated in a nutrient film technique hydroponic system. The additional purpose was to compare the impact of 5I-SA with the effect of a selected KIO3 dose applied separately or together with salicylic acid (SA). The following combinations were tested with the introduction of 5I-SA and KIO3 (together with SA) into the nutrient solution: 1./Control, 2./KIO3 (40.0 μM I.), 3./KIO3 + SA (40.0 μM I and 40.0 μM SA), 4./5I-SA (1.6 μM I), 5./5I-SA (8.0 μM I), and 6./5I-SA (40.0 μM I). A strong toxic effect on plants was revealed only in the case of the highest iodine dose applied as 5I-SA (40.0 μM I). In the remaining combinations, lettuce head weight and its phenotype did not differ from the control. However, an unfavourable effect of 40.0 μM I applied as KIO3 on the chemical composition of plants (the content of sugars, phenolic compounds, and mineral nutrients) was not noted for 5I-SA applied in 1.6 and 8.0 μM I doses. The values of iodine transfer factor for the latter two combinations were higher than after the application of KIO3 or KIO3 + SA. Application of KIO3 + SA increased the uptake and accumulation of iodine in lettuce leaves as compared to the treatment with KIO3 alone. A higher content of 5I-SA was noted in roots than in leaves. The obtained share of 5I-SA in total iodine content indicates that most of this compound is in plants converted into other speciation forms.

Speciation forms of phosphorus in bottom sediments of three selected anthropogenic reservoirs with different trophy degree

Abstract The study presents the results of the research into different phosphorus forms in the bottom sediments of anthropogenic limnic ecosystems i.e. the reservoirs of Pławniowice, Rybnik and Goczałkowice (SP). The bottom sediments of dam reservoirs were investigated by chemical extraction procedure for phosphorus forms. The lowest value of the mean AAP form percentage in the Pławniowice bottom sediments reflected the effect of reclamation with the hypolimnetic removal that had been conducted in the reservoir since 2003. The highest percentage of the RDP form (2%) was found in the Goczałkowice bottom sediments. The order of the specific speciation forms in the bottom sediments of the examined reservoirs was: Rybnik: AAP > EP > WDP > RDP; 4,630> 3,740 > 117 > 65 > 3.5 mgP/kg Pławniowice: AAP > EP > WDP > RDP; 916 > 783 > 107 > 15 > 1.4 mgP/kg Goczałkowice: AAP > WDP > EP > RDP; 686 > 628 > 51 > 7 > 0.14 mgP/kg The mutual correlations between the phosphorus speciation forms (AAP : EP : WDP : RDP) were as follows: Rybnik: 1,323 : 1,068 : 33 : 18 : 1; Pławniowice: 654 : 559 : 76 : 11 : 1; Goczałkowice: 4,900 : 4,485 : 364 : 50 : 1. The comparison of the mean concentration values for specific phosphorus forms in the bottom sediments of the three investigated reservoirs demonstrated that the Rybnik sediments had the highest contents of phosphorus. The contents in Pławniowice and Goczałkowice were 5-7 times lower

Reproductive Isolation through Experimental Manipulation of Sexually Antagonistic Coevolution in Drosophila melanogaster

Promiscuity can drive the evolution of sexual conflict before and after mating occurs. Post mating, the male ejaculate can selfishly manipulate female physiology, leading to a chemical arms race between the sexes. Theory suggests that drift and sexually antagonistic coevolution can cause allopatric populations to evolve different chemical interactions between the sexes, thereby leading to postmating reproductive barriers and speciation. There is, however, little empirical evidence supporting this form of speciation. We tested this theory by creating an experimental evolutionary model of Drosophila melanogaster populations undergoing different levels of interlocus sexual conflict. We found that allopatric populations under elevated sexual conflict show assortative mating, indicating premating reproductive isolation. Further, these allopatric populations also show reduced copulation duration and sperm defense ability when mating happens between individuals across populations compared to that within the same population, indicating postmating prezygotic isolation. Sexual conflict can cause reproductive isolation in allopatric populations through the coevolution of chemical (postmating prezygotic) as well as behavioural (premating) interactions between the sexes. Thus, to our knowledge, we provide the first comprehensive evidence of postmating (as well as premating) reproductive isolation due to sexual conflict.

Habitat preference and flowering-time variation contribute to reproductive isolation between diploid and autotetraploid Anacamptis pyramidalis.

Tetraploid lineages are typically reproductively isolated from their diploid ancestors by post-zygotic isolation via triploid sterility. Nevertheless, polyploids often also exhibit ecological divergence that could contribute to reproductive isolation from diploid ancestors. In this study, we disentangled the contribution of different forms of reproductive isolation between sympatric diploid and autotetraploid individuals of the food-deceptive orchid Anacamptis pyramidalis by quantifying the strength of seven reproductive barriers: three prepollination, one post-pollination prezygotic and three post-zygotic. The overall reproductive isolation between the two cytotypes was found very high, with a preponderant contribution of two prepollination barriers, that is phenological and microhabitat differences. Although the contribution of post-zygotic isolation (triploid sterility) is confirmed in our study, these results highlight that prepollination isolation, not necessarily involving pollinator preference, can represent a strong component of reproductive isolation between different cytotypes. Thus, in the context of polyploidy as quantum speciation, that generates reproductive isolation via triploid sterility, ecological divergence can strengthen the reproductive isolation between cytotypes, reducing the waste of gametes in low fitness interploidy crosses and thus favouring the initial establishment of the polyploid lineage. Under this light, speciation by polyploidy involves ecological processes and should not be strictly considered as a nonecological form of speciation.

Sympatric speciation of the plague microbe Yersinia pestis: Monohostal specialization in the host–parasite marmot–flea (Marmota sibirica–Oropsylla silantiewi) system

An ecological scenario of the origin of the plague microbe that is interpreted in the light of modern Darwinism (synthetic theory of evolution) is presented. It is shown that the plague microbe emerged from a clone of the psychrophilic saprozoonotic pseudotuberculosis microbe Yersinia pseudotuberculosis O:1b in the mountain steppe landscapes of Central Asia in the Sartan time, 22000-15000 years ago, in the monohostal Mongolian marmot (Marmota sibirica)-flea (Oropsylla silantiewi) host-parasite system. It was noted that the evolutionary process described corresponds to the sympatric form of speciation by transition ofthe clone of migrant founders to a new, already-existing ecological niche. It was established that monohostal specialization of the plague microbe was made possible due to heterothermia (5-37 degrees C) of marmots in the hibernation period. The factors of the speciation process--isolation, the struggle for existence, and natural selection--were analyzed.