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PubMed2006

Spectroscopic study on the zinc-contaminated soils for the determination of zinc speciation.

The purpose of this paper reported the zinc species in the highly contaminated soils from metallurgical area around Erh-Jen River in the southern of Taiwan. FTIR and XPS were used to investigate the zinc species in the contaminated soils. Through a FTIR analysis, appreciable of zinc bound by organic matter was found and their bonding structure consisted of antisymmetric and symmetric stretchings, Zn-HSsym and Zn-HSasym. With XPS analysis, the Angstrom scale depth scan was surveyed for investigation the zinc speciation. No signal of zinc was detected in the depth of 900A for the larger particle contaminated soils whereas the detectable signal of zinc was determined in the XPS experiment. With further regression and fitting results, the major zinc species presented in the surface of larger and fine particle contaminated soils consisted of reductive and oxidative zinc species. In the deeper depth of contaminated soils, an inverse spinel zinc ferrite was found in the case of larger particle soil. No inverse spinel zinc ferrite was detected in the case of fine particle soil and could be attributed to the relatively small particle size.

Industrial Waste↗
PubMed2005

Preservation and storage techniques for low-level aqueous mercury speciation.

Although researchers today generally employ appropriate techniques for the storage and preservation of aqueous samples for ambient-level mercury (ppb) speciation, these methods continue to be poorly documented. Numerous experiments were thus conducted to investigate the effects of acidification and bottle type on holding time for various mercury species [elemental mercury (Hg(0)), ionic mercury (Hg(II)), dimethyl mercury (DMHg), monomethyl mercury (MMHg), and dissolved-to-particulate ratio] as well as total mercury (THg). We documented that THg is stable for at least 300 days when stored at 0.4-0.5% acidity in either Teflon or glass bottles. In cases where THg is adsorbed to bottle walls, the addition of BrCl at least 24 h before analysis allowed all Hg to be quantitatively recovered. Polyethylene bottles allowed diffusion of Hg(0) through the bottle walls to or from the sample, depending on the Hg concentration of the sample and storage atmosphere. MMHg in freshwater samples can be stored refrigerated and unacidified for days to weeks with no observed degradation of MMHg. For long-term storage (at least 250 days), samples should be acidified with 0.4% HCl (v/v) and kept in the dark to avoid photodegradation (approximate t(1/2)=6 months). For saltwater samples, preservation with 0.2% (v/v) H(2)SO(4) is preferred to avoid exceeding the optimal chloride concentration if the distillation procedure is used for MMHg determination. For volatile species (Hg(0) and DMHg), samples should be collected in completely full glass bottles with Teflon-lined caps, as these species are lost rapidly (t(1/2)=10-20 h) from Teflon and polyethylene bottles. Because acids can enhance the rapid oxidation of volatile species, these samples should be stored refrigerated and unacidified and processed within 1-2 days if they cannot be purged and trapped in the field. Hg(II) and the dissolved-to-particulate ratio are more stable and can be stored for a period of days to weeks without preservation.

Environmental Monitoring↗
PubMed2005

Mercury distribution and speciation in Lake Balaton, Hungary.

The distribution and speciation of mercury in air, rain, lake water, sediment, and zooplankton in Lake Balaton (Hungary) were investigated between 1999 and 2002. In air, total gaseous mercury (TGM) ranged from 0.4 to 5.9 ng m(-3) and particulate phase mercury (PPM) from 0.01 to 0.39 ng m(-3). Higher concentrations of both TGM and PPM occurred during daytime. Higher concentrations of PPM occurred in winter. In rain and snow, total mercury ranged from 10.8 to 36.7 ng L(-1) in summer but levels up to 191 ng L(-1) in winter. Monomethylmercury (MMHg) concentrations ranged from 0.09 to 1.26 ng L(-1) and showed no seasonal variations. Total Hg in the unfiltered lake water varied spatially, with concentrations ranging from 1.4 to 6.5 ng L(-1). Approximately 70% of the total Hg is dissolved. MMHg levels ranged from 0.08 to 0.44 ng L(-1) as total and from 0.05 to 0.37 ng L(-1) in the dissolved form. Lower Hg concentrations in the water column occurred in winter. In suspended particulate matter and in sediment, total mercury ranged from 9 to 160 ng g(-1) dw, and MMHg ranged from 0.07 to 0.84 ng g(-1) dw. In zooplankton, an average mercury level of 31.0+/-6.8 ng g(-1) dw occurred, with MMHg accounting for approximately 17%. In sediments, suspended-matter- and zooplankton-high Hg and MMHg levels occurred at the mouth of the River Zala, but, in the lake, higher concentrations occurred on the Northern side, and an increasing trend from north-west to north-east was observed. In general, regarding Hg, Lake Balaton can be considered as a relatively uncontaminated site. The high-pH and well-oxygenated water as well as the low organic matter content of the sediment does not favour the methylation of Hg. In addition, bioconcentration and bioaccumulation factors are relatively low compared to other aquatic systems.

Air Pollutants↗
PubMed2005

Arsenic speciation in river and estuarine waters from southwest Spain.

An arsenic speciation survey was carried out in water samples from the Tinto and Odiel Rivers (southwest of Spain), as well as their common estuary. Both rivers are affected by acid mine drainage (AMD) and represent an input of heavy metals into the estuary, which also suffers from industrial water discharges. Samples were taken in December 2000 and July 2001. The arsenic species considered were arsenite (As(III)), arsenate (As(V)), monomethylarsonic (MMA) and dimethylarsinic (DMA) ions using coupled high-performance liquid chromatography-hydride generation-inductively coupled plasma-mass spectrometry (HPLC-HG-ICP-MS) for their determination. Parameters such as pH, salinity, redox potential and dissolved O2 were also measured. The results revealed that the acid mine drainage originating mainly during winter along the upper part of the Tinto River course causes high inorganic concentrations of dissolved arsenic, up to 600 microg l(-1) of As(III) and 200 microg l(-1) of As(V). In summer, As(III) levels decreased due to the diminution of the input from acid mine drainage and also because of oxidation, with a corresponding increase of As(V) level. Furthermore, the extreme acidic conditions of this river (pH 2.3-2-6) do not allow biological activity sufficient to produce significant concentrations of methylated arsenic species. The arsenic concentrations in the nearby Odiel River were always 5-10 times lower than in the Tinto River, with arsenic levels usually below 100 microg l(-1), dominated by As(V), indicating that it is less affected by acid mine drainage. The highest inorganic arsenic species concentrations were found where the river crosses a mining site, which corresponds to the highest As(III) values. Significant biological activity in this river produced methylated species that were detected along the water-course, with the highest concentrations at the lower course of the river, accounting for up to 53-61% of the total dissolved arsenic. At the common estuary formed by both rivers, only arsenate was detected in most samples at lower concentrations than in the riverine water samples. The tidal cycle showed a similar pattern of dilution of the arsenate when seawater comes into the estuary. Methylated species were not found either in summer or winter, at least at the 0.1 microg l(-1) level, possibly because of the high turbidity of the waters, producing an inhibition of the phytoplankton activity. In addition to the riverine inputs into the common estuary, industrial activity also represents an important source of arsenic as the discharge from a Cu smelter produced the highest arsenate level of all samples in estuary and also the only sample with significant arsenite concentration. Furthermore, the underlying iron-oxide-rich sediments represent an importance source of arsenic into the water column. In three nearby estuaries not affected by industrial activity or acid mine drainage, arsenic levels remained below detection limits.

Arsenicals↗
PubMed2005

Organotin speciation in Bizerte lagoon (Tunisia).

For the first time, organotins have been assessed in samples collected from Bizerte lagoon, in Tunisia, during two seasons (summer and winter). The organotin distribution was studied in marine sediments and mussels tissues of this lagoon. Butyl-, phenyl- and octyltins were determined using a rapid speciation analytical method based on one-step ethylation/extraction with sodium tetraethylborate in aqueous phase. Simultaneously to the ethylation, the extraction was performed by either liquid/liquid extraction (LLE) or head-space solid phase microextraction (HS-SPME). Gas chromatography with pulsed flame photometric detection (GC-PFPD) was used to perform quantitative determination. The technique has been validated using biological and sediment reference materials. The different samples from Bizerte lagoon were found to be moderately contaminated, especially by butyltins. This pollution was attributed to industrial activities, which are very important in this area. Organotins appeared accumulated in both sediments and mussels, while significant degradations of triorganotins to monosubstituted ones was observed in water.

Animals↗
PubMed2005

Determining speciation of Pb in phosphate-amended soils: method limitations.

Determining the effectiveness of in situ immobilization for P-amended, Pb-contaminated soils has typically relied on non-spectroscopic methods. However in recent years, these methods have come under scrutiny due to technical and unforeseen error issues. In this study, we analyzed 18 soil samples via X-ray diffraction (XRD), selective sequential extraction (SSE), and a physiologically based extraction test (PBET). The data were compared against each other and to previous data collected for the soil samples employing X-ray absorption fine structure spectroscopy coupled with linear combination fitting (XAFS-LCF), which spectroscopically speciates and quantifies the major Pb species in the samples. It was observed that XRD was incapable of detecting pyromorphite, the hopeful endpoint of the immobilization strategy for reduced Pb bioavailability in our studies. Further, the SSE and PBET extraction methods demonstrated an increase of recalcitrant Pb forms in comparison to the XAFS-LCF results suggesting that SSE and PBET methods induced the precipitation of pyromorphite during the extraction procedures. The theme of this paper illustrates the experimental concerns of several commonly employed methods to investigate immobilization strategies of amended, metal-contaminated systems which may not be in true equilibrium. We conclude that appropriate application of spectroscopic methods provides more conclusive and accurate results in environmental systems (i.e., Pb, Zn, Cd, etc.) examining P-induced immobilization.

Environmental Monitoring↗
PubMed2006

Arsenic speciation in moso bamboo shoot--a terrestrial plant that contains organoarsenic species.

Arsenic is predominantly found as an inorganic species in most terrestrial plants. However, we found that a significant proportion of organic arsenic was present in moso bamboo (Phyllostachys pubescens Mazel) shoot in a market survey of arsenic species in edible terrestrial plants. Moso bamboo shoots from different producing areas in China were collected for analysis to confirm the ubiquity of methylated arsenic species. The total arsenic concentrations of bamboo shoots were determined by hydride generation coupled atomic fluorescence spectrometry (HG-AFS), ranging from 27.7 to 94.0 microg/kg. Information about arsenic species was acquired from cold trap-hydride generation-atomic absorption spectrometry (CT-HG-AAS). Dimethylarsinic acid (DMA) was present in the amount of 13.9% to 44.9% of sum of the arsenic species in all these samples. Monomethylarsonic acid (MMA) and trimethylarsine oxide (TMAO) were also detected in certain samples in the range of 4.2-16.5% and 11.8-18.4%, respectively. In addition, bamboo shoots collected in winter were found to have more total arsenic and organic arsenic than those collected in spring. To investigate the source of the organic arsenic in moso bamboo shoots, arsenic species in the rhizosphere soils of the plants were examined. The absence of organic arsenic in soils would suggest the possibility of formation of methylated arsenic in the plants. In addition, studies of arsenic speciation in the peel and core of winter bamboo shoots showed that all the cores contained organic arsenic while no organic arsenic was detected in the peels. The study provides useful information for better understanding of the distribution of arsenic species in terrestrial plants.

Arsenicals↗
PubMed2006

Metal speciation in sulphidic sediments: a new method based on oxidation kinetics modelling in the presence of EDTA.

The solid phase partitioning of metals (Zn, Cu and Pb) was determined in four anoxic, metal polluted sediments by investigating at pH 8 the 1 day oxidation kinetics of the metal sulphide phases present in the sediments in a background solution containing excess EDTA. A mathematical model consisting of a combination of two pseudo-first order reactions was used to fit the metal release data as a function of oxidation time. The model permitted to fractionate the trace metals in a 'quickly-oxidizable' and a 'slowly-oxidizable' fraction, which could be assigned to two different trace metal pools, respectively (1) FeS minerals (e.g. amorphous FeS, mackinawite) and (2) discrete trace metal sulphide phases. The sum of the fractions associated with these sulphide pools was taken as an approximation for the sulphide-associated fraction of the trace metals and coincided (for the case of Zn and Pb) with the sulphide-associated fraction derived from the analysis of acid volatile sulphide (AVS) and simultaneously extracted metals (SEM). Oxidation kinetics modelling allowed also determining the sulphide-associated fraction of a broad range of trace metals (as demonstrated for Cu) more accurately than the AVS/SEM method, which suffers from non-efficient extraction of a number of trace metal sulphides. A correction was made for the determination of the sulphide-associated fraction by subtracting the trace metal fraction dissolved after 1 day under anoxic conditions in the background EDTA solution. The combination of (1) one day oxidation kinetics modelling and (2) correction for the 1 day anoxic EDTA-soluble fraction is a suitable method to determine accurately the true sulphide speciation of trace metals in anoxic sediments.

Edetic Acid↗
PubMed2007

Mobilization and speciation of chromium in compost: a methodological approach.

An integral approach to study the mobility of chromium in compost is presented. The approach is based on batch pH dependence leaching tests and the analysis of the leachates for total chromium, chromium(VI) and complexes of chromium(III) with natural organic matter. As leachings are performed with no aggressive reagents (ultrapure water with added nitric acid or potassium hydroxide), the method can be considered a good approach to simulate natural scenarios. The analysis of leachates is complemented with the determination of total chromium and total Cr(VI) in the solid sample. Speciation analysis are done by high performance liquid chromatography with inductively coupled plasma mass spectrometry as detection technique; Cr(VI) is determined by ion chromatography, whereas Cr(III) complexes with natural organic matter by size exclusion chromatography. In the compost studied, Cr(VI) accounted for 6% of the total chromium in the solid, whereas no significant amounts of Cr(VI) were mobilized in the pH range studied (4-10). Chromium is mobilized as Cr(III) bound to organic matter, both to humic and fulvic acids, with an increasing contribution of humic acids at higher pHs.

Benzopyrans↗
PubMed2005

Arsenic exposure, urinary arsenic speciation, and peripheral vascular disease in blackfoot disease-hyperendemic villages in Taiwan.

Long-term exposure to ingested inorganic arsenic is associated with peripheral vascular disease (PVD) in the blackfoot disease (BFD)-hyperendemic area in Taiwan. This study further examined the interaction between arsenic exposure and urinary arsenic speciation on the risk of PVD. A total of 479 (220 men and 259 women) adults residing in the BFD-hyperendemic area were studied. Doppler ultrasound was used to diagnose PVD. Arsenic exposure was estimated by an index of cumulative arsenic exposure (CAE). Urinary levels of total arsenic, inorganic arsenite (As(III)) and arsenate (As(V)), monomethylarsonic acid (MMA(V)), and dimethylarsinic acid (DMA(V)) were determined. Primary methylation index [PMI = MMA(V)/(As(III) + As(V))] and secondary methylation index (SMI = DMA(V)/MMA(V)) were calculated. The association between PVD and urinary arsenic parameters was evaluated with consideration of the interaction with CAE and the confounding effects of age, sex, body mass index, total cholesterol, triglycerides, cigarette smoking, and alcohol consumption. Results showed that aging was associated with a diminishing capacity to methylate inorganic arsenic and women possessed a more efficient arsenic methylation capacity than men did. PVD risk increased with a higher CAE and a lower capacity to methylate arsenic to DMA(V). The multivariate-adjusted odds ratios for CAE of 0, 0.1-15.4, and >15.4 mg/L x year were 1.00, 3.41 (0.74-15.78), and 4.62 (0.96-22.21), respectively (P < 0.05, trend test); and for PMI < or = 1.77 and SMI > 6.93, PMI > 1.77 and SMI > 6.93, PMI > 1.77 and SMI < or = 6.93, and PMI < or = 1.77 and SMI < or = 6.93 were 1.00, 2.93 (0.90-9.52), 2.85 (1.05-7.73), and 3.60 (1.12-11.56), respectively (P < 0.05, trend test). It was concluded that individuals with a higher arsenic exposure and a lower capacity to methylate inorganic arsenic to DMA(V) have a higher risk of developing PVD in the BFD-hyperendemic area in Taiwan.

Age Factors↗
PubMed2004

Cooperate or speciate: new theory for the distribution of passerine birds.

In cooperatively breeding birds, adults often forego reproduction and help care for the offspring of others. A universal explanation for this mode of breeding has eluded evolutionary biologists, who have considered it to be a rare, and largely Australian, phenomenon. In a recent paper, Andrew Cockburn reports that the number of known cooperative breeders among oscine passerine birds has more than doubled since the last substantial review, published 16 years ago. Cooperative breeding is often the ancestral trait, and predominantly cooperative genera are species poor compared with their pair-breeding counterparts. Cockburn argues that speciation is less likely in cooperative clades, because the philopatric tendencies of individuals make them poor dispersers, colonizers and migrants. This new hypothesis helps explain the distribution and composition of migrant and island avifauna. However, a major challenge remains to reconcile the roles of phylogenetic history and current ecology in promoting cooperative behaviour.

Journal Article↗
PubMed2004

SINEs of speciation: tracking lineages with retroposons.

The value of short interspersed elements (SINEs) for diagnosing common ancestry is being expanded to examine the differential sorting of lineages through the course of speciation events. Because most SINEs are neutral markers of identical descent, are not precisely excised from the genome and have a known ancestral condition, they are advantageous for reconciling gene trees and species trees with minimal phylogenetic error. A population perspective on SINE evolution combined with coalescence theory provides a context for investigating the phenomenon of ancestral polymorphism and its role in producing incongruent SINE insertion patterns among multiple loci. Studies of human Alu repeats demonstrate the value of young polymorphic SINEs for assessing human genomic diversity and tracking ancient demographics of human populations, whereas incongruent insertion patterns revealed by older fixed SINE loci, such as those in African cichlid fishes, contain information that might help identify ancient radiations that are otherwise obscured by accumulated mutations in sequence data. Here, we review the utility of retroposons for inferring common ancestry, discuss limits to the method, and clarify confusion by providing examples from the literature that illustrate how discordant multi-locus insertion patterns of retroelements can indicate lineage-sorting events that should not be misinterpreted as phylogenetic noise.

Journal Article↗
PubMed2004

Arsenic-sulfides confound anion exchange resin speciation of aqueous arsenic.

A field-portable anion exchange resin method (often cited as the Ficklin method (1983)) has been extensively used to distinguish between dissolved arsenite (As(III)) and arsenate (As(V)) species in natural waters. As(III) occurs largely as As(OH)(3), which is uncharged at ca. pH 7, while As(V) is negatively charged and will sorb to the resin. However, we show that negatively charged As(III)-sulfide (thioarsenite) species, important at sulfide concentrations >10 microM, also bind to the anion exchange resins, and therefore might be interpreted incorrectly as As(V). Furthermore, we show that nitrogen-purging, which results in a conversion of As(III)-sulfides to arsenite, can be used to obtain accurate arsenic speciation when resins are used on sulfidic water samples.

Adsorption↗
PubMed2004

Cloud point extraction for speciation of chromium in water samples by electrothermal atomic absorption spectrometry.

A new method based on the cloud point extraction (CPE) separation and electrothermal atomic absorption spectrometry (ETAAS) detection was proposed for the determination of chromium species. When the system temperature is higher than the cloud point extraction temperature (CPT) of selected surfactant p-octyl polyethyleneglycolphenyether (Triton X-100), the complex of Cr(VI) with dibromophenylfluorone (Br-PF) could enter surfactant-rich phase, whereas the Cr(III) remained in aqueous phase. Thus, an in situ separation of Cr(VI) and Cr(III) could be realized. Cr(VI) in surfactant-rich phase was analyzed by ETAAS and Cr(III) was calculated by subtracting of Cr(VI) from the total chromium which was directly determined by ETAAS. The main factors affecting the cloud point extraction, such as pH, concentration of Br-PF and Triton X-100, equilibration temperature and time, were investigated systematically. Under the optimized conditions, the quantitation limit for Cr(VI) as low as 0.01 microg/L was obtained by preconcentrating a 10 mL sample solution, and the relative standard deviation (n=6, c=2.0 microg/L) was 2.6%. The proposed method was applied to the speciation of chromium in different water samples and the recoveries in the range of 98.9-105.3% were obtained by spiking the real samples. In order to verify the accuracy of the method, a certified reference water sample was analyzed and the results obtained were in good agreement with the certified values.

Cations↗
PubMed2005

Influence of the sediment on lead speciation in the Tagus estuary.

The aim of this work is to study the influence of the Tagus estuarine sediment on lead speciation in the overlying natural water. The water sample in the presence of the sediment was contaminated three times with Pb(II) in a laboratory experiment. In different periods of time, at 1-7 days after each contamination, small volumes of water were titrated with lead. The titration was followed by anodic stripping voltammetry in differential pulse mode. Before and after contamination systematic analysis of the voltammetric parameters (peak current, peak potential and peak width) were carried out to get a clear picture of Pb(II) complexation in the soluble fraction in contact with the sediment. Two main types of organic ligands, macromolecular ligands and small compounds, were detected before contamination. Both of them form labile complexes (degree of lability within the timescale of some milliseconds). The small compounds, with a diffusion coefficient similar to that of the free metal ion, present a homogeneous behaviour in terms of Pb complexation. On the other hand macromolecular ligands, with a diffusion coefficient of 1.2 x 10(-6) cm2s(-1), can be described by two different binding groups, which might be of phenolic and carboxylic type as presented by humic matter. The sediment eliminated lead contamination (10(-6) moldm(-3) was the maximum concentration added) from 12 dm3 of water (surface of 8 dm2) within 2 days. It was also found that the sediment released organic ligands responsible for both labile and inert Pb complexes "seen" by voltammetry. The release of organic ligands that decreases the bioavailability of Pb(II) was clearly detected 1 week after contamination. Therefore, the sediment acts as a buffer for lead through two mechanisms against lead contamination: removing lead ions from the solution and releasing organic ligands to the water column. In a short period of time the sediment responds as a self-cleaning system for Pb(II) contamination in the estuarine water, which may have a very important influence in environmental pollution.

Diffusion↗
PubMed2006

Enhanced recovery of arsenite sorbed onto synthetic oxides by L-ascorbic acid addition to phosphate solution: calibrating a sequential leaching method for the speciation analysis of arsenic in natural samples.

Stripping voltammetry capable of detecting 0.3microg/L arsenate and arsenite was applied for speciation analysis of arsenic sorbed onto synthetic ferrihydrite, goethite at As/Fe ratio of approximately 1.5mg/g with or without birnessite after sequential extraction using 1M phosphate (24 and 16 h) and 1.2M HCl (1h). Precautions to avoid oxygen were undertaken by extracting under anaerobic conditions and by adding 0.1M l-ascorbic acid to 1M NaH(2)PO(4) (pH 5). Addition of l-ascorbic acid did not reduce As(V) to As(III). The recovery rate for As(III) using l-ascorbic acid for extraction (pH 5) but not for adsorption was 81% and 74% of total sorbed As, and was 99% and 97% of extracted As for ferrihydrite and goethite, respectively. Birnessite oxidized most As(III) during the adsorption procedure. l-ascorbic acid used both in adsorption and extraction procedures improved the recovery of As(III) to 79-94% for ferrihydrite-birnessite and 57-94% for goethite-birnessite systems with Fe/Mn ratios of 7, 70, 140 and 280g/g.

Adsorption↗
PubMed2004

Molecular and cytogenetic evidence for cryptic speciation within a rare endemic Malagasy lemur, the Northern Sportive Lemur (Lepilemur septentrionalis).

Evolutionary relationships of different populations of the threatened malagasy lemur Lepilemur septentrionalis were assessed by sequence analysis of mitochondrial DNA (D-loop region and partial Cyt b gene). One hundred and fifty nine samples were collected from five main different localities in the northern part of Madagascar. We applied the phylogenetic species concept based on fixed diagnostic differences to determine the status of different geographical populations. No nucleotide site diagnoses Ankarana from Andrafiamena or Analamera. However, numerous fixed differences separate Sahafary from all other populations. These results were corroborated by phylogenetic trees. As previous cytogenetic studies, our molecular data suggest that two cryptic species of Lepilemur occur in the extreme north of Madagascar. This speciation is probably caused by chromosomal rearrangements in at least one of the evolutionary lineages. Our study comprises another striking example of how molecular genetic assay can detect phylogenetic discontinuities that are not reflected in traditional morphologically based taxonomies. Our study indicates that the Sahafary population is a hitherto undescribed endangered endemic species which urgently needs conservation efforts.

Animals↗
PubMed2004

Phylogeny of a Macaronesian radiation: host-plant use and possible cryptic speciation in Liparthrum bark beetles.

The Macaronesian islands are well known for their unique endemic floras of woody plants. Many of these unusual plant groups provide important novel resources for bark and wood boring beetles which breed in dead or moribund parts of their host plants. The bark beetle genus Liparthrum exploits a wide range of unusual host plants and has its highest proportion of species living on the Macaronesian Islands. We used DNA sequences of the mitochondrial Cytochrome Oxidase I gene and the nuclear Elongation Factor 1 alpha gene, and morphological characters, to estimate the phylogenetic relationships among species endemic to these archipelagos, and to trace the evolution of host-plant use. All parsimony and Bayesian analyses of the combined data, and maximum likelihood analyses of the molecular data, showed that species associated with Euphorbia are monophyletic. We also found genetic and subtle morphological evidence for three cases of cryptic speciation in one polyphyletic species associated with different Euphorbia plants, showing that high levels of host specialisation can occur also in insects breeding in older and very dry, dead plant tissues.

Adaptation, Biological↗