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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Genetic characterization of Western European noble crayfish populations (Astacus astacus) for advanced conservation management strategies
Schrimpf, A. ; Piscione, M. ; Cammaerts, R. ; Collas, M. ; Herman, D. ; Jung, A. ; Ottburg, F. ; Roessink, I. ; Rollin, X. ; Schulz, R. ; Theissinger, K. - \ 2017
Conservation Genetics 18 (2017)6. - ISSN 1566-0621 - p. 1299 - 1315.
Artificial stocking - Management units - Microsatellite analysis - MtDNA sequences - Population genetic diversity - Species conservation

One central goal of conservation biology is to conserve the genetic diversity of species in order to protect their adaptive potential. The main objective of this study was to identify management units (MUs) for the threatened noble crayfish (Astacus astacus) in Western Europe by utilizing sequence and microsatellite analysis to determine populations in need of focused conservation programs. With the analysis of noble crayfish from 31 sampling sites from Belgium, France, The Netherlands and Germany, and further comparison of this data with a European-wide dataset, we propose four distinct MUs: the French Meuse (MU 1), the French Rhine (MU 2), the Belgian Scheldt and Meuse (MU 3) as well as populations from the French Seine (MU 4). This knowledge enables advanced A. astacus conservation management practises in these catchments by distinguishing between outbreeding and inbreeding populations and by preserving the maximum genetic diversity. When required, a high genetic diversity can be conserved by strengthen existing populations via stocking with populations that either bear the most common haplotype or population-specific private haplotypes in order to maintain recent and regional adaptions. Above all, stocking with populations that exhibit haplotypes from outside Western Europe should be avoided in these catchments. This study supports the preservation of the genetic diversity of noble crayfish in Western Europe and provides thus a proposition for advanced conservation management.

Utilizing the global land cover 2000 reference dataset for a comparative accuracy assessment of global 1 km land cover maps
Schultz, M. ; Tsendbazar, N.E. ; Herold, M. ; Jung, A. ; Mayaux, P. ; Goehman, H. - \ 2015
In: 36th International Symposium on Remote Sensing of Environment. - ISPRS (The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ) - p. 503 - 510.
Many investigators use global land cover (GLC) maps for different purposes, such as an input for global climate models. The current
GLC maps used for such purposes are based on different remote sensing data, methodologies and legends. Consequently,
comparison of GLC maps is difficult and information about their relative utility is limited. The objective of this study is to analyse
and compare the thematic accuracies of GLC maps (i.e., IGBP-DISCover, UMD, MODIS, GLC2000 and SYNMAP) at 1 km
resolutions by (a) re-analysing the GLC2000 reference dataset, (b) applying a generalized GLC legend and (c) comparing their
thematic accuracies at different homogeneity levels. The accuracy assessment was based on the GLC2000 reference dataset with
1253 samples that were visually interpreted. The legends of the GLC maps and the reference datasets were harmonized into 11
general land cover classes. There results show that the map accuracy estimates vary up to 10-16% depending on the homogeneity of
the reference point (HRP) for all the GLC maps. An increase of the HRP resulted in higher overall accuracies but reduced accuracy
confidence for the GLC maps due to less number of accountable samples. The overall accuracy of the SYNMAP was the highest at
any HRP level followed by the GLC2000. The overall accuracies of the maps also varied by up to 10% depending on the definition
of agreement between the reference and map categories in heterogeneous landscape. A careful consideration of heterogeneous
landscape is therefore recommended for future accuracy assessments of land cover maps.
* Corresponding author
1. INTRODUCTION
The consistent and continuous observation of land cover is one
of the most important foundations for understanding the Earth’s
environment and ecosystems (Verburg et al., 2011). Currently,
several global land cover datasets (GLC) have been developed
and these datasets are evolving towards higher spatial resolution
(Gong et al., 2013; Mora et al., 2014) . Most GLC maps were
developed by individual groups as one-time efforts and the
subsequent mapping standards reflect the varied interests,
requirements and methodologies of the originating programs
(Herold et al., 2006). These differences of GLC maps and the
effects of their quality on the model outcome are not always
considered when selecting a map as an input for specific
modeling applications (Verburg et al., 2011). Uncertainties of
GLC maps can result in considerable differences in modeling
outcomes (Hibbard et al., 2010; Nakaegawa, 2011; Verburg et
al., 2011).
The accuracies of GLC maps are assessed using independent
validation datasets and regional maps or cross validated against
training datasets. The results of accuracy assessments of
previous maps indicate that overall area-weighted accuracy is
around 70% for the existing GLC maps (Defourny et al., 2012).
However, the use of different approaches in the GLC map
production (e.g., classification scheme, data sources and
algorithms) as well as in validation data collection (e.g.,
sampling scheme, data source and method of reference
classification) raise inconsistency issues and make map
comparisons difficult. Several comparative analyses of land
cover maps were conducted at regional levels
Baseline leptin and leptin reduction predict improvements in metabolic variables and long-term fat loss in obese children and adolescents: a prospective study of an inpatient weight-loss program
Murer, S.B. ; Knopfli, B.H. ; Aeberli, I. ; Jung, A. ; Wildhaber, J. ; Wildhaber-Brooks, J. ; Zimmermann, M.B. - \ 2011
American Journal of Clinical Nutrition 93 (2011)4. - ISSN 0002-9165 - p. 695 - 702.
blood-brain-barrier - serum leptin - body-weight - insulin-resistance - loss maintenance - plasma leptin - overweight - adiposity - life - intervention
Background: It is unclear whether high plasma leptin in obese individuals represents leptin resistance or whether individuals with marked reductions in leptin concentrations in response to weight loss may be at greater risk of regaining weight. Moreover, whether changes in leptin predict metabolic improvements during weight loss is uncertain. Objective: The objective was to prospectively examine associations between plasma leptin, body fat, and weight and metabolic risk factors in obese children during weight loss. Design: In obese children and adolescents [n = 203; mean age: 14.1 y, >98th body mass index (BMI) percentile for age and sex] participating in a 2-mo inpatient weight-loss program, we measured changes in body composition (by dual-energy X-ray absorptiometry), plasma leptin, insulin, and lipids. After discharge, anthropometric measures and plasma leptin were remeasured at 6 (n = 139) and 12 (n = 100) mo. Results: During the 2-mo program, mean (±SD) weight and fat loss were 13.9 ± 4.0 kg and 9.2 ± 2.5 kg, respectively; and mean plasma leptin decreased by 76%. Weight and fat loss were sustained, and no significant differences in BMI-SD score (SDS) or body composition were found between 12 and 2 mo. Baseline leptin was a negative predictor for percentage fat loss at 2, 6, and 12 mo (P <0.05). The percentage change in leptin during the 2-mo intervention positively correlated with the relative change in fasting insulin, the relative change in LDL cholesterol at 2 mo, percentage fat loss, and change in BMI-SDS at 2 and 6 mo (P <0.02). Conclusions: Even in obese children with strongly elevated baseline leptin, large leptin reductions that predict short- and long-term loss of body fat and improvements in lipids and insulin sensitivity can be achieved. Thus, increased plasma leptin in obese children may not necessarily reflect leptin resistance; many children appear to remain leptin sensitive at this age.
During Rapid Weight Loss in Obese Children, Reductions in TSH Predict Improvements in Insulin Sensitivity Independent of Changes in Body Weight or Fat
Aeberli, I. ; Jung, A. ; Murer, S.B. ; Wildhaber, J. ; Wildhaber-Brooks, J. ; Knopfli, B.H. ; Zimmermann, M.B. - \ 2010
Journal of Clinical Endocrinology and Metabolism 95 (2010)12. - ISSN 0021-972X - p. 5412 - 5418.
coronary-heart-disease - subclinical hypothyroidism - thyroid-function - reference range - morbid-obesity - in-vivo - leptin - risk - adolescents - population
Background: Although serum TSH is often elevated in obesity and may be linked to disorders of lipid and glucose metabolism, the clinical relevance of these relationships remains unclear. Subjects: Subjects were obese children and adolescents (n = 206; mean age 14 yr) undergoing rapid weight and fat loss in a standardized, multidisciplinary, 2-month, in-patient weight loss program. Design: This was a prospective study that determined thyroid function, glucose and lipid parameters, leptin, anthropometric measures, and body composition measured by dual-energy x-ray absorption at baseline and at the end of the intervention. Results: At baseline, 52% of children had TSH concentrations in the high normal range (> 2.5 mU/liter), but TSH was not correlated with body weight, body mass index SD scores, lean body mass, or body fat percentage. At baseline, independent of adiposity, TSH significantly correlated with total cholesterol (P = 0.008), low-density lipoprotein cholesterol (P = 0.013), fasting insulin (P = 0.010), homeostatic model assessment (HOMA) (P = 0.004), and leptin (P = 0.006). During the intervention, mean body fat, TSH, HOMA, and fasting insulin decreased by 21, 11, 53, and 54%, respectively. Change (Delta) in TSH did not correlate with Delta body weight or Delta body composition, but Delta TSH significantly correlated with, Delta fasting insulin and Delta HOMA, independent of Delta body weight or Delta body composition (P <0.05). Conclusion: TSH concentrations are elevated in obese children but are not correlated with the amount of excess body weight or fat. During weight loss, independent of changes in body weight or composition, decreases in elevated serum TSH predict decreases in fasting insulin and HOMA. These findings suggest interventions that target high TSH concentrations during weight loss in obese subjects may improve insulin sensitivity. (J Clin Endocrinol Metab 95: 5412-5418, 2010)
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