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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Distribution of orbicules in Annonaceae mirrors evolutionary trend in angiosperms
Huysmans, S. ; Verstraete, B. ; Smets, E. ; Chatrou, L.W. - \ 2010
Plant Ecology and Evolution 143 (2010)2. - ISSN 2032-3913 - p. 199 - 211.
asimina-triloba annonaceae - pollen wall development - sporoderm development - developmental events - callose dissolution - flowering plants - tapetum types - magnoliales - rubiaceae - characters
Background and aims - Orbicules or Ubisch bodies have been recorded in many angiosperm families and although the first observations date back to 1865, their function in the anther remains enigmatic. In flowering plants a general evolutionary trend is observed from common occurrence of orbicules in early diverging lineages towards a more patchy distribution in derived clades of eudicots. Annonaceae was our family of choice for an in depth study of orbicule distribution in early diverging angiosperms since it met the following three criteria: (1) high tapetum diversity, (2) orbicule presence and absence recorded, and (3) recent phylogeny at genus level available. Key results - Our SEM data of eighteen species show that orbicules are more common in Annonaceae than previously perceived. The resulting orbicule distribution pattern on the family topology indicates a consistent absence of orbicules in the 'long branch clade' while orbicules are present in Anaxagorea, the ambavioids, and the 'short branch clade'. Presence of orbicules is the ancestral condition in the family. Morphologically, Annonaceae orbicules are small (<1 µm), spherical and smooth. Conclusions - The orbicule distribution pattern in Annonaceae reflects the general evolutionary trend in flowering plants. We hypothesize that orbicule presence can be considered as a powerful proxy for non-amoeboid tapetum characterization in Annonaceae.
Bias and conflict in phylogenetic inference of myco-heterotrophic plants: a case study in Thismiaceae
Merckx, V. ; Bakker, F.T. ; Huysmans, K. ; Smets, B.F. - \ 2009
Cladistics-The International Journal of the Willi Hennig Society 25 (2009)1. - ISSN 0748-3007 - p. 64 - 77.
long-branch attraction - 18s rdna sequences - parasitic plants - nucleotide substitution - flowering plants - tree selection - molecular-data - gene-transfer - data sets - burmanniaceae
Due to morphological reduction and absence of amplifiable plastid genes, the identification of photosynthetic relatives of heterotrophic plants is problematic. Although nuclear and mitochondrial gene sequences may offer a welcome alternative source of phylogenetic markers, the presence of rate heterogeneity in these genes may introduce bias/systematic error in phylogenetic analyses. We examine the phylogenetic position of Thismiaceae based on nuclear 18S rDNA and mitochondrial atpA DNA sequence data, as well as using parsimony, likelihood and Bayesian inference methods. Significant differences in evolutionary rates of these genes between closely related taxa lead to conflicting results: while parsimony analyses of 18S rDNA and combined data strongly support the monophyly of Thismiaceae, Bayesian inference, with and without a relaxed molecular clock, as well as the Swofford-Olsen-Waddell-Hillis (SOWH) test confidently reject this hypothesis. We show that rate heterogeneity in our data leads to long-branch attraction artifacts in parsimony analysis. However, using model-based inference methods the question of whether Thismiaceae are monophyletic remains elusive. On the one hand maximum likelihood nonparametric bootstrapping and parametric hypothesis tests fail to support a paraphyletic Thismiaceae, on the other hand Bayesian inference methods (both without and with a relaxed clock) significantly reject a monophyletic Thismiaceae. These results show that an adequate sampling, the use of rate homogeneous data, and the application of different inference methods are important factors for developing phylogenetic hypotheses of myco-heterotrophic plants
Diversification of myco-heterotrophic angiosperms: evidence from Burmanniaceae.
Merckx, V. ; Chatrou, L.W. ; Lemaire, B. ; Sainge, M.N. ; Huysmans, S. ; Smets, E.F. - \ 2008
BMC Evolutionary Biology 8 (2008). - ISSN 1471-2148 - 16 p.
long-distance dispersal - arbuscular mycorrhizal fungi - historical biogeography - molecular phylogenies - divergence times - chloroplast genome - flowering plants - absolute rates - sequence data - rain-forest
Background - Myco-heterotrophy evolved independently several times during angiosperm evolution. Although many species of myco-heterotrophic plants are highly endemic and long-distance dispersal seems unlikely, some genera are widely dispersed and have pantropical distributions, often with large disjunctions. Traditionally this has been interpreted as evidence for an old age of these taxa. However, due to their scarcity and highly reduced plastid genomes our understanding about the evolutionary histories of the angiosperm myco-heterotrophic groups is poor. Results - We provide a hypothesis for the diversification of the myco-heterotrophic family Burmanniaceae. Phylogenetic inference, combined with biogeographical analyses, molecular divergence time estimates, and diversification analyses suggest that Burmanniaceae originated in West Gondwana and started to diversify during the Late Cretaceous. Diversification and migration of the species-rich pantropical genera Burmannia and Gymnosiphon display congruent patterns. Diversification began during the Eocene, when global temperatures peaked and tropical forests occurred at low latitudes. Simultaneous migration from the New to the Old World in Burmannia and Gymnosiphon occurred via boreotropical migration routes. Subsequent Oligocene cooling and breakup of boreotropical flora ended New-Old World migration and caused a gradual decrease in diversification rate in Burmanniaceae. Conclusion - Our results indicate that extant diversity and pantropical distribution of myco-heterotrophic Burmanniaceae is the result of diversification and boreotropical migration during the Eocene when tropical rain forest expanded dramatically
TETRAD : electronic identification and on line telematic surveillance of animals and animal products during transports
Mulkens, F. ; Saatkamp, H.W. ; Goossens, K. ; Huysmans, K. ; Buys, N. ; Geers, R. - \ 2000
In: Proceedings of the 10th Internationa Congress on Animal Hygiene, ISAH 2000, Maastricht, The Netherlands, 2000 / Tielen, M.J.M., Voets, M.Th., - p. 195 - 199.
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