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ABSTRACT: We characterized ten polymorphic microsatellite loci from the tree-hole tick, Ixodes arboricola. Loci were screened in 11-18 individuals from three Belgian populations and five to ten alleles were found at each locus. Seven loci did not show deviations from Hardy-Weinberg equilibrium conditions and there were no indications for null alleles at these loci. The three other loci showed significant heterozygote deficiencies in at least one population, and a high potential for the occurrence of null alleles. We observed no effect of potential host DNA on the scoring of the microsatellites. Cross-amplification of the microsatellites was tested in eight specimens of three congeneric species: I. ricinus, I. hexagonus and I. frontalis. Depending on the species, six or seven of the loci were amplified in ≥4 of the 8 specimens and were polymorphic in each of these species (except for Ixaf 11 in I. frontalis and I. ricinus). These loci thus provide a tool for population genetic analysis of I. arboricola. The suitability of these markers needs to be further investigated in its congeners.
Experimental and Applied Acarology 05/2013; · 1.39 Impact Factor
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ABSTRACT: The green lacewing Chrysoperla carnea is a complex of cryptic species whose differentiation has been so far based upon morphology, ecophysiology, behaviour and preliminary mitochondrial DNA data using cytochrome oxidase subunit II (COII) and NADH dehydrogenase subunit II. In this work we extended the DNA data by screening nucleotide sequences of COII, cytochrome oxidase I, cytochrome b and the large ribosomal subunit of the mtDNA. These new data suggest that C. carnea s.s. is a well-supported, separate taxon, but that other taxa of the complex are not consistently differentiated by the current DNA data.
Journal of Zoological Systematics and Evolutionary Research 02/2013; 44(2):180-184. · 1.95 Impact Factor
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ABSTRACT: Arion subfuscus sensu lato (s. l.) refers to a cryptic slug species complex that is native to Europe and which, from there, has been introduced
into the northeastern U.S. The species complex was detected in California for the first time in 2005 and recently 12 specimens
were collected during statewide surveys. The genital morphology of these specimens suggested that only A. subfuscus sensu stricto (s. s.) was present and partial sequences of mitochondrial 16S rDNA (443bp) showed that they all belonged
to a single haplotype of the mitochondrial lineage, S1 sensu Pinceel et al. (Genetica 125: 155–171, 2005). This result was
corroborated by a parallel analysis of a 655bp COI DNA barcode. The 16S rDNA S1 haplotype (S1-03) of the Californian specimens
is hitherto known only from the northeastern U.S. Hence, it is likely that populations may have been introduced to California
from the northeastern states, rather than directly from the native area of the S1 haplogroup in Europe.
Keywords
Arion subfuscus
-Introduced slugs-Cryptic species-Morphology-Molecular identification-Source location of introduction
Biological Invasions 04/2012; 13(1):61-66. · 2.90 Impact Factor
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ABSTRACT: If alternative phenotypes in polymorphic populations do not mate randomly, they can be used as model systems to study adaptive diversification and possibly the early stages of sympatric speciation. In this case, non random mating is expected to support genetic divergence among the different phenotypes. In the present study, we use population genetic analyses to test putatively neutral genetic divergence (of microsatellite loci) among three colour morphs of the lizard Podarcis melisellensis, which is associated with differences in male morphology, performance and behaviour. We found weak evidence of genetic divergence, indicating that gene flow is somewhat restricted among morphs and suggesting possible adaptive diversification.
Genetica 03/2010; 138(3):387-93. · 2.15 Impact Factor
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ABSTRACT: Three paratypes of Arion fagophilus were electrophoretically compared with nine other West European species of the genus Arion. Esterases, glutamate-oxaloacetate-transaminase, a-amylase, superoxide dismutase, phosphoglucomutase, fumarase, α-glycerophosphate dehydrogenase and phosphogluconate dehydrogenase were screened in the hepatopancreas and general proteins in the albumen gland. A. fagophilus appears to be a very well defined species, which may be assigned to the subgenus Kobeltia. The subgeneric division of the genus Arion is preliminary discussed with respect to electrophoretic and chromosomal data. It is concluded to retain four subgenera, which may be grouped two by two: Mesarion and Arion s. s. on one hand, and Kobeltia and Carinarion on the other. It is remarked that the electrophoretic differences between Norwegian and Belgian A. ater suggest a separation into two taxa.
Journal of Zoological Systematics and Evolutionary Research 04/2009; 25(3):169 - 180. · 1.95 Impact Factor
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ABSTRACT: Molecular sequence data are often aligned on the basis of secondary and/or tertiary structure models. However, these models are regularly updated and sometimes differ depending on the way in which they were constructed. We examined whether the choice of a particular 18S rRNA secondary structure model as alignment basis influences phylogeny inference. We therefore compared 18S rRNA phylogenies derived from alignments based on different models. We used: 1. Maximum parsimony; 2. The neighbour-joining method; 3. The maximum-likelihood approach; and 4. Evolutionary parsimony. This demonstrated that the secondary structure model on which an alignment is based may influence: 1. The tree topologies found by these four methods; 2. The numbers of most parsimonious trees found; and 3. The statistical values calculated by the evolutionary parsimony method.
Journal of Zoological Systematics and Evolutionary Research 04/2009; 34(3):135 - 143. · 1.95 Impact Factor
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ABSTRACT: We describe polymerase chain reaction primers and amplification conditions for 13 highly polymorphic microsatellite DNA loci isolated from the Dalmatian wall lizard, Podarcis melisellensis. The number of alleles per locus ranged from 12 to 41, with levels of observed heterozygosity between 0.62 and 0.94. Most of these loci were successfully cross-amplified in the closely related species P. sicula, but levels of polymorphism were always lower.
Molecular Ecology Resources 01/2009; 9(1):299-301. · 3.06 Impact Factor
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ABSTRACT: Extremely high levels of intraspecific mtDNA differences in pulmonate gastropods have been reported repeatedly and several hypotheses to explain them have been postulated. We studied the phylogeny and phylogeography of 51 populations (n = 843) of the highly polymorphic terrestrial slug Arion subfuscus (Draparnaud, 1805) across its native distribution range in Western Europe. By combining the analysis of single stranded conformation polymorphisms (SSCP) and nucleotide sequencing, we obtained individual sequence data for a fragment of the mitochondrial 16S rDNA and a fragment of the nuclear ITS1. Additionally, five polymorphic allozyme loci were scored. Based on the 16S rDNA phylogeny, five monophyletic haplotype groups with sequence divergences of 9-21% were found. Despite this deep mitochondrial divergence, the haplotype groups were not monophyletic for the nuclear ITS1 fragment and haplotype group-specific allozyme alleles were not found. Although there is evidence for an accelerated mtDNA clock, the divergence among the haplotype groups is older than the Pleistocene and their current allopatric ranges probably reflect allopatric divergence and glacial survival in separate refugia from which different post-glacial colonization routes were established. A range-overlap of two mtDNA groups (S1 and S2, 21% sequence divergence) stretched from Central France and Belgium up to the North of the British Isles. The nuclear data suggest that this secondary contact resulted in hybridization between the allopatrically diverged groups. Therefore, it seems that, at least for two of the groups, the deep mtDNA divergence was only partially accompanied by the formation of reproductive isolation.
Journal of Evolutionary Biology 10/2005; 18(5):1264-80. · 3.28 Impact Factor
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ABSTRACT: As Darwinulidae (Ostracoda) are considered to be ancient asexuals with a wide geographical and ecological distribution, they are expected to have accumulated mutations during a long timeframe. However, previous studies on genetic variability suggested a low genetic divergence within the darwinulid species Darwinula stevensoni. Here, overall genotopic diversity of D. stevensoni is estimated with the Random Amplified Polymorphic DNA (RAPD) technique. Using six primers revealing 47 consistently scorable polymorphic loci, substantial clonal diversity within this species is detected. Five of the seven surveyed populations are multiclonal. Moreover, the seven populations have a different clonal composition with almost all of the observed clonal genotypes being restricted to single populations, indicating the absence of a single widespread 'clone'. The observed clonal diversity seems to refute the existence of a widespread general purpose genotype for D. stevensoni. However, in light of previously detected uniformity at functional loci, we reconsider the definition of a GPG. We suggest that it need not imply a genome-wide fixed genotype, but rather consists of a set of ecologically relevant genes.
Heredity 09/2004; 93(2):154-60. · 4.60 Impact Factor
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ABSTRACT: The importance and abundance of cryptic species among invertebrate taxa is well documented. Nowadays, taxonomic, phylogenetic and conservation biological studies frequently use molecular markers to delineate cryptic taxa. Such studies, however, often face the problem of the differential resolution of the molecular markers and techniques involved. This issue is explored in the present study of cryptic taxa within the terrestrial slug complex Arion subfuscus/fuscus in continental north-west Europe. To this end, morphological, allozyme and mitochondrial 16S rDNA sequence data have been jointly evaluated. Using allozyme data and gonad type, two distinct groups were consistently delineated, even under sympatric conditions. The 16S rDNA data strongly supported both those groups and even suggested the presence of three distinct taxa within one of them. However, in view of: (1) the allopatric distribution of three OTUs, (2) the lack of allozyme or morphological differentiation, and (3) the extremely high degree of intraspecific mtDNA variation reported in pulmonate gastropods, they are, for the time being, not regarded as valid species under the biological species concept. By means of 16S rDNA and allozyme data, the position of type and topotype material of A. subfuscus s.s. and A. fuscus relative to the newly defined OTUs was determined, thus clarifying the nomenclature of this species complex. Additionally, gonad type proved to be a useful character for distinguishing the two species in north-west Europe. © 2004 The Linnean Society of London, Biological Journal of the Linnean Society, 2004, 83, 23–38.
Biological Journal of the Linnean Society 08/2004; 83(1):23 - 38. · 2.19 Impact Factor
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ABSTRACT: The land snail Leptaxis azorica, endemic on the Azores, was subjected to an electrophoretic (allozymes) and morphometric (genital tract) analysis. Genetic distances suggest the presence of four distinct lineages and are compatible with colonisation proceeding from the eastern, older islands (Santa Maria and São Miguel) to the west (Flores and Corvo). On São Miguel, genetic and morphometric differentiation is concordant with the separate colonisation of two islands that gave rise to the current island 50,000 years ago. The maximum time available for differentiation in isolation (0.55 million years) suggests a high rate of allozyme change between the two lineages on São Miguel. This may be related to population isolation and bottlenecks caused by human and volcanic activity on São Miguel in relatively recent times. This is more prominent in the eastern region where populations are also characterised by reduced genetic variation (loss of alleles and heterozygosity) compared to populations elsewhere.
Heredity 10/2003; 91(3):239-47. · 4.60 Impact Factor
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ABSTRACT: The mollusc fauna of 64 sites in 31 tidal marshes was surveyed along a salinity gradient from freshwater to marine conditions in the river Scheldt (Belgium–The Netherlands). A total of 10649 specimens involving 31 taxa were identified. Salinity turned out to be a major factor in mollusc assemblages in the Scheldt estuary, but other factors can not be excluded. In the marine part five species were common, compared to the brackish part where only Assiminea grayana was abundant. In the freshwater zone species richness was highest (24). There was a significant correlation between flooding frequency and species richness in the tidal freshwater marsh `Durmemonding'. Finally, the survey confirmed the distribution of the amphibious hygromiid snail Pseudotrichia rubiginosa, a species which in Belgium only occurs in the marshes of the tidal freshwater part of the Scheldt and its tributaries.
Hydrobiologia 03/2002; 474(1):189-196. · 1.78 Impact Factor
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ABSTRACT: Variation in esterase expression (EST) has been investigated in 360 specimens of the periwinkle Littorina littorea collected at nine sites along the polluted western Scheldt and the relatively clean eastern Scheldt estuary. Mean number of EST bands differed among the sites, while a Dice similarity based multi-dimensional scaling along with a minimum spanning tree procedure, revealed an estuary based structuring, clustering the most polluted and least saline like sites together. The underlying factors and mechanisms (i.e. selection, regulation) which are responsible for this structuring remain to be determined.
Marine Environmental Research 11/2001; 52(4):373-82. · 2.28 Impact Factor
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ABSTRACT: In this study we present the results of an intersex survey of Littorina littorea along the heavily polluted Western Scheldt estuary (the Netherlands), and record for the first time the intersex phenomenon in L. littorea from Dutch waters. Intersex differed significantly between localities and was the highest in the vicinity of the harbours of Antwerp and Vlissingen, as reflected by the I
Marine Environmental Research 10/2001; 52(3):249-55. · 2.28 Impact Factor
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ABSTRACT: Heavy metals were determined in the soft tissue and shells of the littorinid, Littoraria scabra, and in the sediments of four mangrove areas along the Dar es Salaam coastline where L. scabra was collected. Several metals accumulate, preferentially in the animals' soft body parts, but do not seem to affect the shell morphology of this species. Sediment-metal levels, measured in the direct vicinity of Dar es Salaam have increased dramatically over the last decade. Nonetheless, these levels are still lower compared to metal-sediment levels reported in polluted European and American estuaries. Soft-tissue metal levels detected in L. scabra are, nevertheless, with the exception of Cr and Zn, comparable to metal levels reported in other gastropod species.
Environment International 05/2001; 26(4):243-9. · 5.30 Impact Factor
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Hereditas 02/2001; 134(3):267-70. · 0.79 Impact Factor
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ABSTRACT: Inductively coupled plasma atomic emission spectrophotometry (ICP-AES) was used to determine heavy metal concentrations in the shells and soft tissues of the periwinkle Littorina littorea, collected at seven sites along the Scheldt estuary. Several metals accumulate in the animals soft body parts, and are related to the seawards decreasing pollution gradient. No clear correlation with a previously detected shell size patterning could be established.
Science of The Total Environment 11/2000; 262(1-2):111-21. · 3.29 Impact Factor
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ABSTRACT: The phenetic analysis of non-nodulatingAcacia species by Harrier et al. (1997) was repeated to illustrate how different computer programs may generate alternative UPGMA trees for the very same data, even in the absence of data input order effects (ties). For example, all Harrier et al.''s UPGMA dendrograms produced by software from the Scottish Agricultural Statistics Service differed from those obtained by the packages NTSYS and MVSP87. Particularly, the positions ofA. albida, A. rovumae, andA. pentagona, as well as the relationships betweenDiacanthae andTriacanthae were affected by this phenomenon. Hence, whenever clustering techniques are used, care should be taken to consider possible software-dependent caveats and artefacts. Nevertheless, all programs provided clusterings that largely coincided with the subgeneric and sectional groupings proposed by Vassal (1972) although the positions of some species varied depending on whether morphological or molecular data were considered (e.g.A. albida andA. rovumae).
Plant Systematics and Evolution 08/2000; 220(3):139-146. · 1.34 Impact Factor
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ABSTRACT: During the winter of 1996, a heavy storm crossed the coasts of the Azores. A comparison of wave-exposed and wave-sheltered samples of the intertidal planktonic developing periwinkle Littorina
striata
(Mollusca: Caenogastropoda), collected before and after this storm revealed: (1) an overall difference in relative and absolute aperture area between wave-exposed and wave-sheltered samples; and (2) depending on the technique used a storm (MANOVA/CDA/1994 vs 1996 nested ANOVA) or no storm (1992, 1993, 1994, 1996, nested ANOVA) effect was noted. Preference should be given to the latter analysis as it is more correct in the present context. Nesting of the factor ‘year’ in the factor ‘storm’, allows detection of the true storm effect, disentangling it from other year exposure interactions, while the inclusion of more than one pre-storm sample allows differentiation of storm effects from ‘normal’ temporal variation.
Journal of the Marine Biological Association of the UK 11/1999; 79(06):1129 - 1130. · 1.00 Impact Factor
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ABSTRACT: Nonspecific esterases (EST) are often used to measure genetic variation, yet they may be influenced by environmental factors such as food, climate and age. This may produce misleading similarity indices and genetic diversity estimates (i.e., clone or strain diversities in uniparental organisms). Therefore, polyacrylamide gel electrophoresis (PAGE) and isoelectric focusing (IEF) were used to investigate environmental effects on the EST variation in natural Carinarion populations, as well as in 45 individuals that were raised individually on carrots to produce offspring by selfing. Food effects on EST profiles in these progenies were examined by raising them on different food items (lettuce, nettle, or paper). Our results indicated that: (i) Arion (Carinarion) fasciatus and A. (C.) silvaticus show species-specific EST profiles, (ii) A. fasciatus-like outcrossers most probably are conspecific with A. fasciatus s.s., (iii) not all EST variation has a Mendelian basis since lettuce and nettle altered EST profiles, and (iv) food effects on EST profiles differed strongly between individuals. Although food-induced EST profiles did not affect taxonomic interpretations, they did inflate genetic diversity estimates and thus provided misleading population-genetic data.
Electrophoresis 04/1999; 20(3):473-9. · 3.30 Impact Factor
