Stefan Van Dongen

University of Antwerp, Antwerpen, Flanders, Belgium

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Publications (135)397.73 Total impact

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    ABSTRACT: The often observed directional asymmetry (DA) in human limb bones may have a genetic/developmental basis and/or could emerge from different mechanical loadings across sides due to handedness. Because behavioural lateralization in itself has a genetic basis, it has been suggested that DA in limbs could develop prenatally as a pre-adaptation to adult life. However, the presence of consistent differences in the size of left and right limb bones in early development is understudied. We study asymmetry in limb bones during early development (10-20 weeks of gestation) in a sample of 178 aborted foetuses. Statistically significant DA was found in several upper and lower limb bones, where the right-hand side was consistently larger than the left. We argue that this pattern is probably the consequence of developmental processes related to internal asymmetric positioning of organs.
    Laterality 02/2014; 19(5). DOI:10.1080/1357650X.2014.891606 · 1.13 Impact Factor
  • Stefan Van Dongen
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    ABSTRACT: Abstract Background: Studies of the process of human mate selection and attractiveness have assumed that selection favours morphological features that correlate with (genetic) quality. Degree of masculinity/femininity and fluctuating asymmetry (FA) may signal (genetic) quality, but what information they harboured and how they relate to fitness is still debated. Aim: To study strength of associations between facial masculinity/femininity, facial FA, attractiveness and physical strength in humans. Subjects and methods: Two-hundred young males and females were studied by measuring facial asymmetry and masculinity on the basis of frontal photographs. Attractiveness was determined on the basis of scores given by an anonymous panel, and physical strength using hand grip strength. Results: Patterns differed markedly between males and females and analysis method used (univariate vs multivariate). Overall, no associations between FA and attractiveness, masculinity and physical strength were found. In females, but not males, masculinity and attractiveness correlated negatively and masculinity and physical strength correlated positively. Conclusion: Further research into the differences between males and females in associations between facial morphology, attractiveness and physical strength is clearly needed. The use of a multivariate approach can increase our understanding of which regions of the face harbour specific information of hormone levels and perhaps behavioural traits.
    Annals of Human Biology 02/2014; DOI:10.3109/03014460.2013.847120 · 1.15 Impact Factor
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    ABSTRACT: Ratios of digit lengths are studied intensively as markers of prenatal sex hormone levels. Study sexual dimorphism in ratios of metacarpals, which received less attention. We studied six metacarpal ratios in deceased human fetuses of ages 10 to 42weeks. We found no indication of a sexual dimorphism at this early stage of development.
    Early human development 01/2014; 90(3). DOI:10.1016/j.earlhumdev.2014.01.004 · 1.93 Impact Factor
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    ABSTRACT: Most gait-scoring scales for pigs have a limited number of categories, supposedly to improve repeatability. However, reducing the number of categories could lead to loss of information if the observers' discriminative capacities are underused. With a recently estimated within-herd prevalence of sow lameness of 8.8% to 16.9% in the European Union and the associated losses, the availability of reliable tools for the timely detection of initial cases warrants attention. This study investigated the intra- and inter-observer repeatability (intra-OR and inter-OR) of three gait-scoring scales for sows: a continuous 'tagged' visual analogue scale (tVAS, measured in mm), a 5-point and a 2-point ordinal scale (5P and 2P), all with the same descriptors. Veterinary medicine students (n=108) were trained to use the scales and then asked to score 90 videos (30 per scale) of sows with normal and abnormal gait. Thirty-six videos were shown once and 18 were randomly shown three times, of which one mirrored horizontally. The students' opinions on the scales were also collected. Intra- and inter-OR were higher with the tVAS than the 2P scale (inter-OR: 0.73 v. 0.60; P<0.05. Intra-OR: 0.80 v. 0.67; P<0.05). Intra-OR was higher with the 5P (0.81) than the 2P scale (0.67; P<0.05). For all three scales, repeatabilities were lower (P<0.05) for non-lame sows (gait score of ⩽45 mm on the tVAS) than for sows showing some signs of lameness (gait score>45 mm). Video order (first 45 v. last 45 clips), mirroring, users' opinions on the scales, and previous declared experience in handling pigs or scoring lameness in other species had no effect on repeatabilities. Correlations between the students' and experts' scores were high (tVAS=0.92; 5P=0.91; 2P=0.88) but the association for the 2P was not linear and the frequency distribution showed lower correlations for a group of students. This study confirms recent evidence that it is possible to design high-resolution gait-scoring scales that do not reduce observer repeatability. Visual gait-scoring scales with fewer than five categories are likely to entail loss of information on lameness in individual sows.
    animal 01/2014; DOI:10.1017/S1751731113002462 · 1.78 Impact Factor
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    ABSTRACT: Aneuploidies cause gene-dosage imbalances that presumably result in a generalized decreased developmental homeostasis, which is expected to be detectable through an increase in fluctuating asymmetry (FA) of bilateral symmetric traits. However, support for the link between aneuploidy and FA is currently limited and no comparisons among different aneuploidies have been made. Here, we study FA in deceased human fetuses and infants from a 20-year hospital collection. Mean FA of limb bones was compared among groups of aneuploidies with different prenatal and postnatal survival chances and two reference groups (normal karyogram or no congenital anomalies). Limb asymmetry was 1.5 times higher for aneuploid cases with generally very short life expectancies (trisomy 13, trisomy 18, monosomy X, triploidy) than for trisomy 21 patients and both reference groups with higher life expectancies. Thus, FA levels are highest in groups for which developmental disturbances have been highest. Our results show a significant relationship between fluctuating asymmetry, human genetic disorders and severity of the associated abnormalities.
    Scientific Reports 01/2014; 4:3703. DOI:10.1038/srep03703 · 5.08 Impact Factor
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    ABSTRACT: Fluctuating asymmetry (FA), as an indirect measure of developmental instability (DI), has been intensively studied for associations with stress and fitness. Patterns, however, appear heterogeneous and the underlying causes remain largely unknown. One aspect that has received relatively little attention in the literature is the consequence of direct mechanical effects on asymmetries. The crucial prerequisite for FA to reflect DI is that environmental conditions on both sides should be identical. This condition may be violated during early human development if amniotic fluid volume is deficient, as the resulting mechanical pressures may increase asymmetries. Indeed, we showed that limb bones of deceased human fetuses exhibited increased asymmetry, when there was not sufficient amniotic fluid (and, thus, space) in the uterine cavity. As amniotic fluid deficiency is known to cause substantial asymmetries and abnormal limb development, these subtle asymmetries are probably at least in part caused by the mechanical pressures. On the other hand, deficiencies in amniotic fluid volume are known to be associated with other congenital abnormalities that may disturb DI. More specifically, urogenital abnormalities can directly affect/reduce amniotic fluid volume. We disentangled the direct mechanical effects on FA from the indirect effects of urogenital abnormalities, the latter presumably representing DI. We discovered that both factors contributed significantly to the increase in FA. However, the direct mechanical effect of uterine pressure, albeit statistically significant, appeared less important than the effects of urogenital abnormalities, with an effect size only two-third as large. We, thus, conclude that correcting for the relevant direct factors allowed for a representative test of the association between DI and stress, and confirmed that fetuses form a suitable model system to increase our understanding in patterns of FA and symmetry development.
    PLoS ONE 11/2013; 8(11):e81824. DOI:10.1371/journal.pone.0081824 · 3.53 Impact Factor
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    Matteo Breno, Jessica Bots, Stefan Van Dongen
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    ABSTRACT: Directional asymmetry (DA), where at the population level symmetry differs from zero, has been reported in a wide range of traits and taxa, even for traits in which symmetry is expected to be the target of selection such as limbs or wings. In invertebrates, DA has been suggested to be non-adaptive. In vertebrates, there has been a wealth of research linking morphological asymmetry to behavioural lateralisation. On the other hand, the prenatal expression of DA and evidences for quantitative genetic variation for asymmetry may suggest it is not solely induced by differences in mechanic loading between sides. We estimate quantitative genetic variation of fetal limb asymmetry in a large dataset of rabbits. Our results showed a low but highly significant level of DA that is partially under genetic control for all traits, with forelimbs displaying higher levels of asymmetry. Genetic correlations were positive within limbs, but negative across bones of fore and hind limbs. Environmental correlations were positive for all, but smaller across fore and hind limbs. We discuss our results in light of the existence and maintenance of DA in locomotory traits.
    PLoS ONE 10/2013; 8(10):e76358. DOI:10.1371/journal.pone.0076358 · 3.53 Impact Factor
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  • 64th Annual Meeting of the European Federation of Animal Science, Nantes, France; 08/2013
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    ABSTRACT: Fluctuating asymmetry (the directionally random asymmetry of bilateral structures, FA) is commonly used as a measure of developmental instability, and may increase with stress. As several studies reported a relation between FA and developmental abnormalities, we investigate whether FA could be an additional perhaps more sensitive marker of developmental toxicity. The aim of this work is analyzing patterns of FA in multiple traits in a large dataset of rabbit fetuses, which were prenatally exposed to a toxic compound and sacrificed just before natural delivery. Gravid females were exposed to three doses of this compound, inducing abnormalities in the fetuses at the high dose only. The average FA, however, was already higher than control in rabbit fetuses of the low-dose group but did not further increase with higher concentrations. Moreover, the increase in FA differed between traits, with the hindlimbs showing the strongest response. In addition, we did not find any association between FA and the presence of fetal abnormalities at the individual level. Although these results suggest that FA may act as "an early warning system," we did not find a dose-response relationship with increasing stress and effects were trait-specific. Further testing is needed before FA may be considered as a sensitive marker in developmental toxicity studies.
    Birth Defects Research Part B Developmental and Reproductive Toxicology 08/2013; 98(4). DOI:10.1002/bdrb.21067 · 1.17 Impact Factor
  • Matteo Breno, Jessica Bots, Stefan Van Dongen
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    ABSTRACT: The mechanisms of developmental buffering and its relevance to the evolutionary process have recently attracted a lot of attention in both developmental and evolutionary biology. Among other things, whether the two components of developmental buffering [i.e. canalization and developmental stability (DS)] have a common basis has long been the subject of debate. In the present study, we examine the association between fluctuating asymmetry (i.e. the directionally random asymmetry of bilateral structures), a measure of DS, and between-individual variation of long bones in over 1000 rabbit foetuses. The lack of correlations between fluctuating asymmetry and between-individual variation at the individual, litter and treatment level, in combination with the absence of correspondence among covariance matrices, supports distinct developmental mechanisms for DS and canalization. We discuss our results in the context of recent insights into the mechanisms of developmental buffering.
    Biological Journal of the Linnean Society 06/2013; 109(2-2):434-440. DOI:10.1111/bij.12058 · 2.54 Impact Factor
  • Matteo Breno, Jessica Bots, Stefan Van Dongen
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    ABSTRACT: The genetic basis of developmental instability (DI) remains largely unknown as a result of its morphological expression, fluctuating asymmetry (FA), poorly reflecting DI, especially if few traits are studied. The typically low values of heritability of FA (h2FA) can be translated into higher values of DI (h2DI) by the hypothetical repeatability, yet leading to wide confidence intervals. Thus, high sample sizes and/or several traits are indispensible for reaching meaningful conclusions. To obtain more insights into quantitative genetic variation of DI, we investigated between-family variance in DI in six long bones of 1126 foetuses of the New Zealand white rabbit from a full-sib experiment. We applied different approaches to obtain genetic parameters for DI. Heritabilities and the coefficients of between-family variation (CVB) were calculated for six individual traits and composite indices. The results obtained, despite a likely upward bias as a result of maternal and non-additive effects, lend support to the presence of moderate additive genetic variance for DI. It is suggested that, in foetal traits, the environmental variance was minimal, leading to a high likelihood of detecting genetic variation in DI, thus creating an ideal model system for studying the genetic basis of DI.
    Biological Journal of the Linnean Society 05/2013; 109(1):33-42. DOI:10.1111/bij.12051 · 2.54 Impact Factor
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    ABSTRACT: Although bird-tick systems affect the human risk of tick-borne diseases, very little is known about the ecological factors that shape the spatio-temporal variation of tick infestations in terrestrial songbirds. We present a risk model that explains the levels of infestation of Ixodes ricinus, the main vector of Borrelia burgdorferi s.l., during the breeding season of the great tit (Parus major), one of Europe's most abundant avian reservoir hosts of Borrelia burgdorferi s.l.. Tit tick burden were modeled as a function of variables summarizing vegetation, climate, proxies for mammal abundance and characteristics of individual birds and their nests. Tick loads were positively associated with the relative humidity prior to capture of the bird and the cover of bracken inside its territory. The number of cold winter days prior to the bird's breeding season showed a negative association with tick loads. None of the proxies for mammal abundance correlated with tick loads. Tick loads decreased with age in female tits, whereas they increased with age in male tits. Tick burdens in the parental tits were positively associated with their brood size and negatively correlated with the average nestling body weight. Possible mechanisms include: how tit foraging influences tick encounter rates, host tick resistance mechanisms and the environmental conditions that simultaneously affect tick exposure risk and brood characteristics. We believe this study provides the first detailed insights into the ecological factors that shape tick burden in a terrestrial songbird.
    International journal for parasitology 04/2013; DOI:10.1016/j.ijpara.2013.02.007 · 3.40 Impact Factor
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    ABSTRACT: The study of asymmetry can provide insights into genetic and environmental influences on organismal development. Directional asymmetry (DA) can be either adaptive or non-adaptive, whereas fluctuating asymmetry (FA) – defined as small non-directional departures from symmetry in bilateral traits – is thought to be an indicator of genetic or environmental stress experienced during development. Using data from 28 European populations, we assessed the degree of DA and FA in the lateral plates of threespine sticklebacks Gasterosteus aculeatus and surveyed the direction of DA and differences in levels of DA and FA in different habitat types (viz. marine, lake and river populations). DA differed between habitats, with right-biased DA found in the marine populations and no directional bias found in lake and river populations. Differences in DA among habitats may be a by-product of habitat-specific developmental instability resulting in asymmetry, or it may indicate habitat-specific differences in selection against/for symmetry, as has been proposed in previous research of sticklebacks. Also, the presence of FA varied depending upon habitat type, but it also depended on plate morph – a variable confounded with the habitat effect. While we cannot rule out factors such as stress as a cause of population differences in FA, it may also simply be a by-product of other evolutionary processes (e.g. lateral plate number reduction) without functional basis.
    Journal of Zoology 04/2013; 289(4). DOI:10.1111/jzo.12005 · 1.95 Impact Factor
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    ABSTRACT: Thirteen microsatellite loci for the threatened orange coral, Astroides calycularis have been designed. The polymorphism of these thirteen loci was tested in 24 polyps from different colonies. The results show that the allele numbers for each loci ranged from 2 to 14 (mean Na=5.1), with an average observed heterozygosity of 0.47 (He=0.45). These new loci could be useful for studies on conservation genetic research on populations of this species and help improve the resolution of individual identification. Primers were also tested in four different species of Tubastrea, the Dendrophillyd genus more phylogenetically close to Astroides, with successful amplifications for the majority of the loci.
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    ABSTRACT: While fluctuating asymmetry (FA; small, random deviations from perfect symmetry in bilaterally symmetrical traits) is widely regarded as a proxy for environmental and genetic stress effects, empirical associations between FA and stress are often weak or heterogeneous among traits. A conceptually important source of heterogeneity in relationships with FA is variation in the selection history of the trait(s) under study, i.e. traits that experienced a (recent) history of directional change are predicted to be developmentally less stable, potentially through the loss of canalizing modifiers. Here we applied X-ray photography on museum specimens and live captures to test to what extent the magnitude of FA and FA-stress relationships covary with directional shifts in traits related to the flight apparatus of four East-African rainforest birds that underwent recent shifts in habitat quality and landscape connectivity. Both the magnitude and direction of phenotypic change varied among species, with some traits increasing in size while others decreased or maintained their original size. In three of the four species, traits that underwent larger directional changes were less strongly buffered against random perturbations during their development, and traits that increased in size over time developed more asymmetrically than those that decreased. As we believe that spurious relationships due to biased comparisons of historic (museum specimens) and current (field captures) samples can be ruled out, these results support the largely untested hypothesis that directional shifts may increase the sensitivity of developing traits to random perturbations of environmental or genetic origin.
    PLoS ONE 03/2013; 8(3):e57966. DOI:10.1371/journal.pone.0057966 · 3.53 Impact Factor
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    ABSTRACT: Mouthpart deformities in chironomids have been reported to indicate adverse effects of environmental pollutants. The authors assessed rates of mouthpart deformities in tributyltin-exposed, inbred, and outcrossed Chironomus riparius larvae over multiple generations. The authros found that the occurrence of mouthpart deformities was significantly correlated with inbreeding, whereas no correlation was found with the tributyltin exposure. The present study confirms the strong effect of high inbreeding rates on developmental deformities in chironomids. Environ. Toxicol. Chem. © 2012 SETAC.
    Environmental Toxicology and Chemistry 02/2013; 32(2). DOI:10.1002/etc.2071 · 2.83 Impact Factor
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    ABSTRACT: Homeotic transformations of vertebrae are particularly common in humans and tend to come associated with malformations in a wide variety of organ systems. In a dataset of 1,389 deceased human foetuses and infants a majority had cervical ribs and approximately half of these individuals also had missing twelfth ribs or lumbar ribs. In ~10 % of all cases there was an additional shift of the lumbo-sacral boundary and, hence, homeotic transformations resulted in shifts of at least three vertebral boundaries. We found a strong coupling between the abnormality of the vertebral patterns and the amount and strength of associated malformations, i.e., the longer the disturbance of the vertebral patterning has lasted, the more associated malformations have developed and the more organ systems are affected. The germ layer of origin of the malformations was not significantly associated with the frequency of vertebral patterns. In contrast, we find significant associations with the different developmental mechanisms that are involved in the causation of the malformations, that is, segmentation, neural crest development, left-right patterning, etc. Our results, thus, suggest that locally perceived developmental signals are more important for the developmental outcome than the origin of the cells. The low robustness of vertebral A-P patterning apparent from the large number of homeotic transformations is probably caused by the strong interactivity of developmental processes and the low redundancy of involved morphogens during early organogenesis. Additionally, the early irreversibility of the specification of the A-P identity of vertebrae probably adds to the vulnerability of the process by limiting the possibility for recovery from developmental disturbances. The low developmental robustness of vertebral A-P patterning contrasts with a high robustness of the A-P patterning of the vertebral regions. Not only the order is invariable, also the variation in the number of vertebrae per region is small. This robustness is in agreement with the evolutionary stability of vertebral regions in tetrapods. Finally, we propose a new hypothesis regarding the constancy of the presacral number of vertebrae in mammals.
    Evolutionary Biology 12/2012; 39(4):456-471. DOI:10.1007/s11692-012-9196-1 · 3.27 Impact Factor
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    ABSTRACT: Because broiler chickens are juvenile animals undergoing physical development, stocking density during rearing may influence this development. Some of these physical changes may cause welfare problems, for example, decreased bone quality, which may lead to fracture during catching and transport. Others do not influence welfare directly but can be used as indicators of the animal's ability to cope with its environment (e.g., fluctuating asymmetry). The present study evaluates the effect of stocking density on bone quality and fluctuating asymmetry. Birds were stocked at densities of 2.4, 5.8, 8.8, 12.1, 13.6, 15.5, 18.5, and 21.8 birds/m(2) from 1 until 39 d of age. Increased stocking density had a negative effect on some aspects of bone quality (tibia curvature and shear strength). Tibias were shorter at high density, possibly due to increased curvature. Several other bone quality aspects (tibia weight, torsion, and dyschondroplasia, and femur curvature and epiphysis shape) remained unaffected. Middle-toe length was the only character that showed a significant increase with increasing density when each character was analyzed separately. Nevertheless, a composite index of fluctuating asymmetry, which combined data on all 11 measured characters, tended to increase with stocking density. Such increased fluctuating asymmetry may indicate decreased welfare. However, one of the assumptions of fluctuating asymmetry is that the animal is subjected to the same environmental influences on both sides. This assumption may not be fulfilled when leg deformations occur, as these may lead to asymmetric changes in bone growth by altering the division of force over the 2 legs. In addition, leg deformations decrease the accuracy of bone length measurements made in a straight line. This raises some concerns on the applicability of fluctuating asymmetry measurements on broiler chicken legs, especially because stocking density did not effect the asymmetry of the head.
    Poultry Science 08/2012; 91(8):1759-67. DOI:10.3382/ps.2011-01859 · 1.54 Impact Factor

Publication Stats

3k Citations
397.73 Total Impact Points

Institutions

  • 1995–2014
    • University of Antwerp
      • Department of Biology
      Antwerpen, Flanders, Belgium
  • 2010
    • Estación Biológica de Doñana
      Hispalis, Andalusia, Spain
  • 2007
    • Institute for Agricultural and Fisheries Research
      • Animal Sciences Unit
      Meirelbeke, Flanders, Belgium
  • 2002
    • Janssen Pharmaceutica
      Beersse, Flanders, Belgium
  • 1998–2001
    • Lund University
      • Department of Biology
      Lund, Skåne, Sweden