Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Ghost Introgression: Spooky Gene Flow in the Distant Past
    Ottenburghs, Jente - \ 2020
    Bioessays 42 (2020)6. - ISSN 0265-9247
    adaptation - demographic modelling - hybridization - macroevolution - phylogenetic networks - reproductive isolation - speciation

    Evolution is a continuous trial and error process in which most lineages go extinct without leaving fossil remains. Many of these lineages would be closely related and occasionally hybridized with lineages that gave rise to extant species. Hence, it is likely that one can find genetic signatures of these ancient introgression events in present-day genomes, so-called ghost introgression. The increasing availability of high-quality genome assemblies for non-model organisms and the development of more sophisticated methods for detecting introgression will undoubtedly reveal more cases of ghost introgression, indicating that the Tree of Life is even more reticulated than assumed. The presence of ghost introgression has important consequences for the study of numerous evolutionary processes, including adaptation, speciation, and macroevolutionary patterns. In addition, detailed studies of introgressed regions could provide insights into the morphology of the extinct lineage, providing an unexpected link between genomics and the fossil record. Hence, new methods that take into account ghost introgression will need to be developed.

    The Role of Transcriptional Regulation in Hybrid Vigor
    Botet, Ramon ; Keurentjes, Joost J.B. - \ 2020
    Frontiers in Plant Science 11 (2020). - ISSN 1664-462X
    Arabidopsis thaliana - breeding - gene expression - genetic regulation - heterosis - hybrid vigor - natural variation - speciation

    The genetic basis of hybrid vigor in plants remains largely unsolved but strong evidence suggests that variation in transcriptional regulation can explain many aspects of this phenomenon. Natural variation in transcriptional regulation is highly abundant in virtually all species and thus a potential source of heterotic variability. Allele Specific Expression (ASE), which is tightly linked to parent of origin effects and modulated by complex interactions in cis and in trans, is generally considered to play a key role in explaining the differences between hybrids and parental lines. Here we discuss the recent developments in elucidating the role of transcriptional variation in a number of aspects of hybrid vigor, thereby bridging old paradigms and hypotheses with contemporary research in various species.

    Data underlying the research of Geochemical multi-surface modeling of reactive zinc speciation in compost as influenced by extraction conditions
    Klinkert, Susan ; Comans, Rob ; Groenenberg, Bert Jan - \ 2020
    Wageningen University & Research
    compost - extraction conditions - fractionation - geochemical modelling - organic matter - zinc - speciation
    This dataset includes the data and calculations underlying the modeling work carried out for the scientific manuscript "Geochemical multi-surface modeling of reactive zinc speciation in compost as influenced by extraction conditions".
    Crossing species boundaries : the hybrid histories of the true geese
    Ottenburghs, Jente - \ 2016
    Wageningen University. Promotor(en): Herbert Prins; R.C. Ydenburg, co-promotor(en): Hendrik-Jan Megens. - Wageningen : Wageningen University - ISBN 9789462579781 - 268
    geese - anser - crossing - species - hybridization - speciation - phylogenomics - ganzen - anser - kruisen - soorten - hybridisatie - soortvorming - phylogenomica

    Hybridization, the interbreeding of different species, is a common phenomenon in birds: about 16% of bird species is known to have hybridized with at least one other species. Numerous avian hybrid zones have been studied from a morphological or genetic perspective, often documenting the interspecific exchange of genetic material by hybridization and backcrossing (i.e. introgression). The incidence of hybridization varies among bird orders with the Anseriformes (waterfowl: ducks, geese and swans) showing the highest propensity to hybridize. In this thesis, I provide a genomic perspective on the role of hybridization in the evolutionary history of one particular anseriform tribe, the Anserini or “True Geese”, which comprises 17 species divided over two genera: Anser and Branta . The diversification of this bird group took place in the late Pliocene and the early Pleistocene (between four and two million years ago), conceivably driven by a global cooling trend that led to the establishment of a circumpolar tundra belt and the emergence of temperate grasslands. Most species show a steady population increase during this period, followed by population subdivision during the Last Glacial Maximum about 110,000 to 12,000 years ago. The combination of large effective population sizes and occasional range shifts facilitated contact between the diverging goose species, resulting in high levels of interspecific gene flow. Introgressive hybridization might have enabled these goose populations to quickly adapt to changing environments by transferring of advantageous alleles across species boundaries, increasing standing genetic variation or expanding phenotypic variation of certain traits (e.g., beak morphology). Hybridization seems to be a common and integral component in the evolution and diversification of geese. The pervasiveness of rapid speciation and hybridization in geese complicates the attempt to capture their evolutionary history in a phylogenetic tree, advocating a phylogenetic network approach. Indeed, trying to capture the complex diversification of the True Geese in a branching tree can be regarded as a wild goose chase.

    Methodological approaches for fractionation and speciation to estimate trace element bioavailability in engineered anaerobic digestion ecosystems : An overview
    Hullebusch, Eric D. van; Guibaud, Gilles ; Simon, Stéphane ; Lenz, Markus ; Yekta, Sepehr Shakeri ; Fermoso, Fernando G. ; Jain, Rohan ; Duester, Lars ; Roussel, Jimmy ; Guillon, Emmanuel ; Skyllberg, Ulf ; Almeida, C.M.R. ; Pechaud, Yoan ; Garuti, Mirco ; Frunzo, Luigi ; Esposito, Giovanni ; Carliell-Marquet, Cynthia ; Ortner, Markus ; Collins, Gavin - \ 2016
    Critical Reviews in Environmental Science and Technology 46 (2016)16. - ISSN 1064-3389 - p. 1324 - 1366.
    Anaerobic digestion - analytical methods - bioavailability - fractionation - speciation - trace elements

    Optimal supply of trace elements (TE) is a prerequisite for microbial growth and activity in anaerobic digestion (AD) bioprocesses. However, the required concentrations and ratios of essential TE for AD biotechnologies strongly depend on prevailing operating conditions as well as feedstock composition. Furthermore, TE in AD bioreactors undergo complex physicochemical reactions and may be present as free ions, complex bound or as precipitates depending on pH, or on the presence of sulfur compounds or organic macromolecules. To overcome TE deficiency, various commercial mineral products are typically applied to AD processes. The addition of heavy metals poses the risk of overdosing operating systems, which may be toxic to microbial consortia and ultimately the environment. Adequate supplementation, therefore, requires appropriate knowledge not only about the composition, but also on the speciation and bioavailability of TE. However, very little is yet fully understood on this specific issue. Evaluations of TE typically only include the measurement of total TE concentrations but do not consider the chemical forms in which TE exist. Thus detailed information on bioavailability and potential toxicity cannot be provided. This review provides an overview of the state of the art in approaches to determine bioavailable TE in anaerobic bioprocesses, including sequential fractionation and speciation techniques. Critical aspects and considerations, including with respect to sampling and analytical procedures, as well as mathematical modeling, are examined. The approaches discussed in this review are based on our experiences and on previously published studies in the context of the “COST Action 1302: European Network on Ecological Roles of Trace Metals in Anaerobic Biotechnologies.”

    Asymmetric flow field-flow fractionation of manufactured silver nanoparticles spiked into soil solution
    Koopmans, G.F. ; Hiemstra, T. ; Regelink, I.C. ; Molleman, B. ; Comans, R.N.J. - \ 2015
    Journal of Chromatography. A, Including electrophoresis and other separation methods 1392 (2015). - ISSN 0021-9673 - p. 100 - 109.
    natural organic-matter - engineered nanoparticles - calcium-chloride - ionic-strength - humic acids - molar-mass - aggregation - retention - ph - speciation
    Manufactured metallic silver nanoparticles (AgNP) are intensively utilized in consumer products and this will inevitably lead to their release to soils. To assess the environmental risks of AgNP in soils, quantification of both their concentration and size in soil solution is essential. We developed a methodology consisting of asymmetric flow field-flow fractionation (AF4) in combination with on-line detection by UV–vis spectroscopy and off-line HR-ICP-MS measurements to quantify the concentration and size of AgNP, coated with either citrate or polyvinylpyrrolidone (PVP), in water extracts of three different soils. The type of mobile phase was a critical factor in the fractionation of AgNP by AF4. In synthetic systems, fractionation of a series of virgin citrate- and PVP-coated AgNP (10–90 nm) with reasonably high recoveries could only be achieved with ultrahigh purity water as a mobile phase. For the soil water extracts, 0.01% (w:v) sodium dodecyl sulfate (SDS) at pH 8 was the key to a successful fractionation of the AgNP. With SDS, the primary size of AgNP in all soil water extracts could be determined by AF4, except for PVP-coated AgNP when clay colloids were present. The PVP-coated AgNP interacted with colloidal clay minerals, leading to an overestimation of their primary size. Similar interactions between PVP-coated AgNP and clay colloids can take place in the environment and facilitate their transport in soils, aquifers, and surface waters. In conclusion, AF4 in combination with UV–vis spectroscopy and HR-ICP-MS measurements is a powerful tool to characterize AgNP in soil solution if the appropriate mobile phase is used.
    The butterfly plant arms-race escalated by gene and genome duplications
    Edger, P.P. ; Heidel-Fischer, H.M. ; Bekaert, K.M. ; Rota, J. ; Glockner, G. ; Platts, A.E. ; Heckel, D.G. ; Der, J.P. ; Wafula, E.K. ; Tang, M. ; Hofberger, J.A. ; Smithson, A. ; Hall, J.C. ; Blanchette, M. ; Bureau, T.E. ; Wright, S.I. ; dePamphilis, C.W. ; Schranz, M.E. ; Conant, G.C. ; Barker, M.S. ; Wahlberg, N. ; Vogel, H. ; Pires, J.C. ; Wheat, C.W. - \ 2015
    Proceedings of the National Academy of Sciences of the United States of America 112 (2015)27. - ISSN 0027-8424 - p. 8362 - 8366.
    evolutionaire genetica - co-evolutie - diversificatie - brassica - pieridae - papilionidae - glucosinolaten - fylogenie - evolutionary genetics - coevolution - diversification - brassica - pieridae - papilionidae - glucosinolates - phylogeny - diversity - defense - cytochrome-p450 - polymorphism - arabidopsis - metabolism - expression - speciation
    Coevolutionary interactions are thought to have spurred the evolution of key innovations and driven the diversification of much of life on Earth. However, the genetic and evolutionary basis of the innovations that facilitate such interactions remains poorly understood. We examined the coevolutionary interactions between plants (Brassicales) and butterflies (Pieridae), and uncovered evidence for an escalating evolutionary arms-race. Although gradual changes in trait complexity appear to have been facilitated by allelic turnover, key innovations are associated with gene and genome duplications. Furthermore, we show that the origins of both chemical defenses and of molecular counter adaptations were associated with shifts in diversification rates during the arms-race. These findings provide an important connection between the origins of biodiversity, coevolution, and the role of gene and genome duplications as a substrate for novel traits.
    Mesocosm validation of the marine No Effect Concentration of dissolved copper derived from a species sensivity distribution
    Foekema, E.M. ; Kaag, N.H.B.M. ; Kramer, K.J.M. ; Long, K. - \ 2015
    Science of the Total Environment 521-522 (2015). - ISSN 0048-9697 - p. 173 - 182.
    principal response curves - organic-matter - toxicity - water - carbon - speciation - exposure - ph
    The Predicted No Effect Concentration (PNEC) for dissolved copper based on the species sensitivity distribution (SSD) of 24 marine single species tests was validated in marine mesocosms. To achieve this, the impact of actively maintained concentrations of dissolved copper on a marine benthic and planktonic community was studied in 18 outdoor 4.6 m3 mesocosms. Five treatment levels, ranging from 2.9 to 31 µg dissolved Cu/L, were created in triplicate and maintained for 82 days. Clear effects were observed on gastropod and bivalve molluscs, phytoplankton, zooplankton, sponges and sessile algae. The most sensitive biological endpoints; reproduction success of the bivalve Cerastoderma edule, copepod population development and periphyton growth were significantly affected at concentrations of 9.9 µg Cu/L and higher. The No Observed Effect Concentration (NOEC) derived from this study was 5.7 µg dissolved Cu/L. Taking into account the DOC concentration of the mesocosm water this NOEC is comparable to the PNEC derived from the SSD.
    Genomics and the challenging translation into conservation practice
    Shafer, A.B.A. ; Wolf, J.B.W. ; Alves, P.C. ; Bergstrom, L. ; Bruford, M.W. ; Brannstrom, I. ; Colling, G. ; Dalen, L. van; Meester, L. de; Ekblom, R. ; Vergeer, P. - \ 2015
    Trends in Ecology and Evolution 30 (2015)2. - ISSN 0169-5347 - p. 78 - 87.
    genetic diversity - background selection - population genomics - insular population - dna - divergence - speciation - evolution - sequence - markers
    The global loss of biodiversity continues at an alarming rate. Genomic approaches have been suggested as a promising tool for conservation practice as scaling up to genome-wide data can improve traditional conservation genetic inferences and provide qualitatively novel insights. However, the generation of genomic data and subsequent analyses and interpretations remain challenging and largely confined to academic research in ecology and evolution. This generates a gap between basic research and applicable solutions for conservation managers faced with multifaceted problems. Before the real-world conservation potential of genomic research can be realized, we suggest that current infrastructures need to be modified, methods must mature, analytical pipelines need to be developed, and successful case studies must be disseminated to practitioners.
    Structural variations in pig genomes
    Paudel, Y. - \ 2015
    Wageningen University. Promotor(en): Martien Groenen, co-promotor(en): Ole Madsen; Hendrik-Jan Megens. - Wageningen : Wageningen University - ISBN 9789462572171 - 204
    varkens - dierveredeling - genomen - genomica - single nucleotide polymorphism - dna-sequencing - fenotypische variatie - chromosoomafwijkingen - evolutie - soortvorming - pigs - animal breeding - genomes - genomics - single nucleotide polymorphism - dna sequencing - phenotypic variation - chromosome aberrations - evolution - speciation


    Paudel, Y. (2015). Structural variations in pig genomes. PhD thesis, Wageningen University, the Netherlands

    Structural variations are chromosomal rearrangements such as insertions-deletions (INDELs), duplications, inversions, translocations, and copy number variations (CNVs). It has been shown that structural variations are as important as single nucleotide polymorphisms (SNPs) in regards to phenotypic variations. The general aim of this thesis was to use next generation sequencing data to improve our understanding of the evolution of structural variations such as CNVs, and INDELs in pigs. We found that: 1) the frequency of copy number variable regions did not change during pig domestications but rather reflected the demographic history of pigs. 2) CNV of olfactory receptor genes seems to play a role in the on-going speciation of the genus Sus. 3) Variation in copy number of olfactory receptor genes in pigs (Sus scrofa) seems to be shaped by a combination of selection and genetic drift, where the clustering of ORs in the genome is the major source of variation in copy number. 4) Analysis on short INDELs in the pig genome shows that the level of purifying selection of INDELs positively correlates with the functional importance of a genomic region, i.e. strongest purifying selection was observed in gene coding regions. This thesis provides a highly valuable resource for copy number variable regions, INDELs, and SNPs, for future pig genetics and breeding research. Furthermore, this thesis discusses the limitations and improvements of the available tools to conduct structural variation analysis and insights into the future trends in the detection of structural variations.

    Speciation and domestication in Suiformes: a genomic perspective
    Frantz, L.A.F. - \ 2015
    Wageningen University. Promotor(en): Martien Groenen, co-promotor(en): Ole Madsen; Hendrik-Jan Megens. - Wageningen : Wageningen University - ISBN 9789462572546 - 227
    domesticatie - suiformes - soortvorming - dierveredeling - genomica - evolutie - genenstroom - dna-sequencing - moleculaire fylogenetica - domestication - suiformes - speciation - animal breeding - genomics - evolution - gene flow - dna sequencing - molecular phylogenetics


    Frantz, L.A.F. (2015). Speciation and Domestication in Suiformes: a genomic perspective. PhD thesis, Wageningen University, the Netherlands

    The diversity of life on earth owes its existence to the process of speciation. The concept of speciation is primordial for evolutionary biologists because it provides a framework to understand how contemporary biodiversity came to be. Moreover, not only natural phenomena can result in the differentiation of life forms. Indeed, biodiversity can also be the result of direct and indirect human influence such as domestication. In this thesis, I investigate these evolutionary processes (speciation and domestication) in the Suiformes superfamily (pigs and related species). I use complete genome sequences to illuminate many specific aspects of the speciation and domestication in Suiformes as well as to draw general conclusions on these crucial processes. In chapter 2 I show how genomes provide an essential source of information to retrieve deep taxonomic relationships among Suiformes. This allows me to describe multiple novel aspects of their early evolutionary history such as the fact that Suiformes colonised North America at least twice. In this chapter, I further highlight and discuss novel methodological limitations that are inherent to phylogenomics. In chapters 3, 4 and 5 I use genome sequences to resolve the evolutionary history of the genus Sus (domestic pigs and wild boars species). More precisely, I show that, contrary to the expectation of simple models of speciation, the evolutionary history of these species involved alternating periods of gene-flow and genetic differentiation that are tightly linked to past climatic fluctuations that took place over the last 4 million years. In addition, these chapters also provide novel insights into the process of speciation by demonstrating that genetic differentiation between species can be achieved, even when gene-flow is strong. Lastly, in chapter 6 I tested multiple models of domestication for S. scrofa. In this chapter I show that models involving reproductive isolation between wild and domestic forms are incompatible with genomic data. Moreover, this chapter demonstrates that, while domestic pigs are morphologically homogenous, they are not genetically homogenous. Together, these findings have important implications for our understanding of the process of domestication because it shows that this process was not solely the result of captivity. Together, the results of this work not only provide a comprehensive evolutionary history for the Suiformes, but also novel insights into the complex processes (speciation and domestication) that are responsible for the diversity of life on earth.

    Data from: Testing models of speciation from genome sequences: divergence and asymmetric admixture in Island Southeast Asian Sus species during the Plio-Pleistocene climatic fluctuations
    Frantz, L.A.F. ; Madsen, O. ; Megens, H.J.W.C. ; Groenen, M. ; Lohse, H. - \ 2014
    Wageningen UR
    speciation - hybridization - population genetics - empirical - phylogeography - genomics / proteomics - conservation genetics
    In many temperate regions, ice ages promoted range contractions into refugia resulting in divergence (and potentially speciation), while warmer periods led to range expansions and hybridization. However, the impact these climatic oscillations had in many parts of the tropics remains elusive. Here, we investigate this issue using genome sequences of three pig (Sus) species, two of which are found on islands of the Sunda-shelf shallow seas in Island Southeast Asia (ISEA). A previous study revealed signatures of inter-specific admixture between these Sus species (Frantz et al. (2013) Genome sequencing reveals fine scale diversification and reticulation history during speciation in Sus. Genome biology, 14, R107). However, the timing, directionality and extent of this admixture remain unknown. Here we use a likelihood based model comparison to more finely resolve this admixture history and test whether it was mediated by humans or occurred naturally. Our analyses suggest that inter-specific admixture between Sunda-shelf species was most likely asymmetric and occurred long before the arrival of humans in the region. More precisely, we show that these species diverged during the late Pliocene but around 23% of their genomes have been affected by admixture during the later Pleistocene climatic transition. In addition, we show that our method provides a significant improvement over D-statistics which are uninformative about the direction of admixture.
    Neandertal Admixture in Eurasia Confirmed by Maximum-Likelihood Analysis of Three Genomes
    Lohse, K. ; Frantz, L.A.F. - \ 2014
    Genetics 196 (2014)4. - ISSN 0016-6731 - p. 1241 - 1251.
    ancestral population sizes - dna-sequences - divergence - speciation - history - number - recombination - coalescent - migration - inference
    Although there has been much interest in estimating histories of divergence and admixture from genomic data, it has proved difficult to distinguish recent admixture from long-term structure in the ancestral population. Thus, recent genome-wide analyses based on summary statistics have sparked controversy about the possibility of interbreeding between Neandertals and modern humans in Eurasia. Here we derive the probability of full mutational configurations in nonrecombining sequence blocks under both admixture and ancestral structure scenarios. Dividing the genome into short blocks gives an efficient way to compute maximum-likelihood estimates of parameters. We apply this likelihood scheme to triplets of human and Neandertal genomes and compare the relative support for a model of admixture from Neandertals into Eurasian populations after their expansion out of Africa against a history of persistent structure in their common ancestral population in Africa. Our analysis allows us to conclusively reject a model of ancestral structure in Africa and instead reveals strong support for Neandertal admixture in Eurasia at a higher rate (3.4-7.3%) than suggested previously. Using analysis and simulations we show that our inference is more powerful than previous summary statistics and robust to realistic levels of recombination.
    Adsorption of levofloxacin onto goethite: Effects of pH, calcium and phosphate
    Qin, X.P. ; Liu, F. ; Wang, G.C. ; Weng, L. ; Li, L. - \ 2014
    Colloids and Surfaces. B: Biointerfaces 116 (2014). - ISSN 0927-7765 - p. 591 - 596.
    fluoroquinolone antibacterial agents - water interface - ciprofloxacin removal - antibiotic ofloxacin - humic substances - iron-oxides - sorption - complexation - tetracycline - speciation
    Adsorption of levofloxacin (LEV), one of the extensively used antibiotics, onto goethite was investigated using batch experiments. The adsorption of LEV on goethite was pH-dependent. A maximum adsorption was reached at pH 6. Above or below pH 6, the adsorption decreased. In the presence of calcium (Ca2+), a decrease in adsorption was observed, due to probably formation of Ca2+-LEV complexes in solutions. Phosphate also showed a significant inhibition on LEV adsorption over a pH range of 3-10. Phosphate competed with LEV for binding sites on the surface of goethite, and the electrostatic competition between LEV and phosphate on goethite surface might be another reason for the decrease in adsorption. These results indicated that Ca2+ and phosphate have a great influence on the distribution of LEV in soils and waters, which will eventually affect its antibacterial activity in the environment. (C) 2013 Elsevier B.V. All rights reserved.
    A decade of uncertainty: Resolving the phyologenetic position of Diclinanona (Annonaceae), inlcuding taxonomic notes and a key to the species
    Erkens, R.H.J. ; Chatrou, L.W. ; Chaowasku, T. ; Westra, L.I.T. ; Maas, J.W. ; Maas, P.J.M. - \ 2014
    Taxon 63 (2014)6. - ISSN 0040-0262 - p. 1244 - 1252.
    palms sheds light - historical biogeography - global biogeography - evolution - diversification - speciation - genus - taxa - biodiversity - convergence
    The molecular phylogenetic placement of Diclinanona (Annonaceae) has been debated in the literature for a decade. On the basis of morphological studies the genus was thought to be related to genera now all placed in subfam. Annonoideae. This early hypothesis was supported by the first phylogenetic analyses of Annonaceae. However, more recently a placement in subfam. Malmeoideae was hypothesised based on an analysis of more plastid data, thus contradicting older but also new morphological findings and previous phylogenetic work. The current study uses newly sequenced plastid data for two species of Diclinanona to show that the earlier hypothesised placement was correct and discusses the (little) anatomical and morphological data on Diclinanona that is available in a phylogenetic framework. Furthermore, an online revision of the three species of Diclinanona is presented in order to update the taxonomic knowledge of this genus.
    Genetic divergence and evidence for sympatric host-races in the highly polyphagous brown tail moth, Euproctis chrysorrhoea (Lepidoptera: Erebidae)
    Marques, J.F. ; Wang, H.L. ; Svensson, G.P. ; Frago Clols, E. ; Anderbrant, O. - \ 2014
    Evolutionary Ecology 28 (2014)5. - ISSN 0269-7653 - p. 829 - 848.
    plant-feeding insects - tree arbutus-unedo - evolutionary history - mitochondrial - populations - speciation - refugia - time - diversification - differentiation
    The brown tail moth (BTM) Euproctis chrysorrhoea (Linnaeus 1758) (Lepidoptera: Erebidae) is a forest and ornamental pest in Europe and the United States. Its extreme polyphagy, and documented phenological shift associated with host use suggest the presence of distinct host-races. To test this hypothesis, we sampled BTM infesting different host species in several locations along its distribution, and used DNA sequence data (a total of 1,672 bp from cytochrome c oxidase subunit I, elongation factor 1-alpha, and wingless) to produce haplotype networks and reconstruct the phylogenetic relationships between individuals. Population genetic diversity indices pointed out a higher genetic diversity in Europe, particularly in the samples from southern Spain and southern England. Lower F ST values were found between geographically closer populations when compared to more distant ones, but analyses of molecular variance and Mantel tests failed to reveal geographically associated genetic differentiation. However, haplotype networks and phylogenetic reconstructions revealed a previously unknown genetic differentiation within the BTM, with one lineage circumscribed to southern Europe. Although BTM haplotypes did not cluster according to their host plant, host-associated haplotypes were observed within certain geographic regions. Hence, our data support the existence of host-races of BTM within southern Spain and southern England, where populations from different hosts occur in sympatry.
    Characterization of colloidal Fe from soils using field-flow fractionation and Fe K-edge X-ray absorption spectroscopy
    Regelink, I.C. ; Voegelin, A. ; Weng, L. ; Koopmans, G.F. ; Comans, R.N.J. - \ 2014
    Environmental Science and Technology 48 (2014)8. - ISSN 0013-936X - p. 4307 - 4316.
    iron-oxide nanoparticles - natural organic-matter - acid forest soils - exafs spectroscopy - mineral nanoparticles - trace-metals - speciation - surface - ferrihydrite - associations
    Colloids may facilitate the transport of trace elements and nutrients like phosphate in soil. In this study, we characterized soil colloids (
    Differences in olfactory species recognition in the females of two Australian songbird species
    Krause, E.T. ; Brummel, C. ; Kohlwey, S. ; Baier, M.C. ; Müller, C. ; Bonadonna, F. ; Caspers, B.A. - \ 2014
    Behavioral Ecology and Sociobiology 68 (2014)11. - ISSN 0340-5443 - p. 1819 - 1827.
    finches taeniopygia-guttata - zebra finches - odor recognition - kin recognition - wild - birds - nest - cues - discrimination - speciation
    Although birds have recently been shown to possess olfactory abilities and to use chemical cues in communication, limited effort has been made to demonstrate the use of odorants in social contexts. Even less is known regarding the use of odorants in species recognition. The ability to recognize conspecifics should be more pronounced in social species. This study investigated the importance of olfactory cues in species recognition in females of two estrildid finch species with different levels of sociality. Combining odor preference tests with chemical analyses, we surveyed whether female zebra finches and diamond firetails are able to distinguish between the species based on volatile traits and whether individuals exhibit species-specific differences in body odorants. Zebra finches are more social than diamond firetails; nevertheless, both species have an overlapping distribution area. Applying an experimental Y-maze paradigm, we showed that zebra finches can use differences in their species odor fingerprints and displayed a significant preference for the odor of conspecifics over that of heterospecifics, whereas diamond firetails did not reveal a preference. Using gas chromatography and mass spectrometry, we demonstrated that body odorants of the two species were significantly different in relative composition. This finding demonstrates the potential importance of olfactory cues in species recognition, at least in social bird species. Even these two closely related species displayed remarkable differences in their responsiveness to similar chemical cues, which might be caused by species-specific differences in ecology, physiology, or evolution. Keywords Songbird . Zebra finch . Taeniopygia guttata . Diamond firetail . Stagonopleura guttata . Sociality . Olfaction . Smell . Scent . Olfactory fingerprint
    Oral bioaccessibility and human exposure to anthropogenic and geogenic mercury in urban, industrial and mining areas
    Rodrigues, S.M. ; Coelho, C. ; Cruz, N. ; Monteiro, R.J.R. ; Henriques, B. ; Duarte, A.C. ; Romkens, P.F.A.M. ; Pereira, E. - \ 2014
    Science of the Total Environment 496 (2014). - ISSN 0048-9697 - p. 649 - 661.
    atomic-absorption-spectrometry - potentially toxic elements - chloralkali plant - inorganic mercury - part i - contaminated soils - asturias spain - speciation - sediments - portugal
    The objective of this study was to characterize the link between bioaccessibility and fractionation of mercury (Hg) in soils and to provide insight into human exposure to Hg due to inhalation of airborne soil particles and hand-to-mouth ingestion of Hg-bearing soil. Mercury in soils from mining, urban and industrial areas was fractionated in organometallic forms; mobile; semi-mobile; and non-mobile forms as well as HCl-extractable Hg. The in vitro bioaccessibility of Hg was obtained by extracting soils with (1) a simulated human gastric fluid (pH 1.5), and (2) a simulated human lung fluid (pH 7.4). Total soil Hg concentrations ranged from 0.72 to 1.8 mg kg- 1 (urban areas), 0.28 to 94 mg kg- 1 (industrial area) and 0.92 to 37 mg kg- 1 (mining areas). Both organometallic Hg as well as 0.1 M HCl extractable Hg were lower (<0.5% of total Hg) than Hg extracted by gastric fluid (up to 1.8% of total Hg) and lung fluid (up to 12% of total Hg). In addition, Hg extracted by lung fluid was significantly higher in urban and industrial soils (average 5.0–6.6% of total Hg) compared to mining soils. Such differences were related to levels of mobile Hg species in urban and industrial soils compared to mining soils. These results strengthen the need to measure site-specific Hg fractionation when determining Hg bioaccessibility. Results also show that ingestion and/or inhalation of Hg from soil particles can contribute up to 8% of adult total Hg intake when compared to total Hg intake via consumption of contaminated fish and animal products from contaminated areas.
    Chemical communication in tilapia: A comparison of Oreochromis mossambicus with O. niloticus
    Hubbard, P.C. ; Mota, V.C. ; Keller-Costa, T. ; Paulo da Silva, J. ; Canário, A.V.M. - \ 2014
    General and Comparative Endocrinology 207 (2014). - ISSN 0016-6480 - p. 13 - 20.
    maturation-inducing hormone - african cichlid fish - mozambique tilapia - olfactory sensitivity - speciation - pheromone - signals - urine - radiations - evolution
    In allopatric speciation species differentiation generally results from different selective pressures in different environments, and identifying the traits responsible helps to understand the isolation mechanism(s) involved. Male Mozambique tilapia (Oreochromis mossambicus) use urine to signal dominance; furthermore, 5b-pregnane-3a,17,20b-triol-3a-glucuronide (and its a-epimer, 5b-pregnane-3a,17,20atriol-3a-glucuronide), in their urine is a potent pheromone, the concentration of which is correlated with social status. The Nile tilapia (Oreochromis niloticus) is a close relative; species divergence probably resulted from geographical separation around 6 million years ago. This raises the question of whether the two species use similar urinary chemical cues during reproduction. The olfactory potency of urine, and crude extracts, from either species was assessed by the electro-olfactogram and the presence of the steroid glucuronides in urine from the Nile tilapia by liquid-chromatography/mass-spectrometry. Both species showed similar olfactory sensitivity to urine and respective extracts from either species, and similar sensitivity to the steroid glucuronides. 5b-Pregnan-3a,17a,20b-triol-3a-glucuronide was present at high concentrations (approaching 0.5 mM) in urine from Nile tilapia, with 5b-pregnan-3a,17a,20a-triol-3a-glucuronide present at lower concentrations, similar to the Mozambique tilapia. Both species also had similar olfactory sensitivity to estradiol-3-glucuronide, a putative urinary cue from females. Together, these results support the idea that reproductive chemical cues have not been subjected to differing selective pressure. Whether these chemical cues have the same physiological and behavioural roles in O. niloticus as O. mossambicus remains to be investigated.
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