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Violaceae research projects Taxonomy and Phylogeography of West European Violets Kevin van den Hof - NHN Leiden Taxonomic delimitation of Viola subsection Rostratae has always been hampered, because of the relative few characters by which species in the subsection differ, the large amount of phenotypic plasticity within species, and interspecific hybridization. Subsection Rostratae is divided in four groups: the Arosulatae, Mirabilis, Repentes, and Rosulatae series. In this PhD project we focus on Viola persicifolia a member of the Arosulatae series. The Arosulatae group differs from the other series by lacking a basal non-flowering rosette of leaves. The group is restricted to the temperate regions of Eurasia and contains ca. ten species. V. persicifolia is paleotetraploid (2n = 20) and is involved in the alloploid origin of several species in the series. It is a wide spread but rare plant species occurring throughout Europe with the exception of the Mediterranean, the south-east and extreme north of Europe. In the Netherlands its occurrence has always been rare. Two varieties have been described in the Netherlands: V. persicifolia var. persicifolia and V. persicifolia var. lacteaeoides. The former variety is found in the Holocene part of the Netherlands on the borderlines of river and brook valleys. The latter is considered to be endemic for the Netherlands, and has its main distribution in the Pleistocene part of the Netherlands. It is mainly found on the lower parts of moorland on loamy and peaty soil. There are different opinions about the taxonomic status of both varieties. On one side it is argued that both varieties are taxonomically distinct, based on differences in morphology and distribution. Others argue that var. lacteaeoides is merely an ecotype and does not deserve a separate taxonomic status. The first objective will be a phylogeographic analysis of V. persicifolia to reconstruct the post-glacial migration routes into the Netherlands. This will lead to better insights on how it dispersed across Europe and how it arrived in the Netherlands. It will also be a useful tool to investigate the taxonomic status of varieties V. persicifolia var. persicifolia and V. persicifolia var. lacteaeoides, which is important for conservation guidelines. The second objective of this PhD project will be to come to a better delimitation of the species in subsection Rostratae occurring in the Netherlands. Therefore, V. persicifolia with its closest relatives and their hybrid products will be studied in a phylogenetic context. Currently I am searching for a chloroplast marker that shows enough intraspecific variation to reconstruct the post-glacial migration routes into the Netherlands.
Host tracking by Cymothoe (Nymphalidae) feeding on Rinorea (Violaceae): evolution & mechanisms of association Robin van Velzen - NHN Wageningen Identifying factors driving patterns of association between phytophagous insects and their host plants is one of the main themes in the field of insect-plant interactions. One hypothesis states that host shifts are predominant, and possibly adaptive, and mediated by the functional similarities of secondary chemistry in the hosts. An alternative hypothesis is that host shifts are rare, and insect lineages remain associated with their plants hosts, a process which may eventually result in parallel cladogenesis or cospeciation. This project considers the evolution of host plant associations of Cymothoe butterflies feeding on Rinorea. This phytophagous system is unique within current knowledge of Nymphalidae host plant relationships because of its high level of specificity and the large number of congeneric species involved. My research aims at using a comparative phylogenetic, experimental approach by combining insect and host-plant phylogenetic trees with data from host-plant phytochemistry and behavioural experiments. This will enable us to go beyond correlations and similarity, and provide actual experimental evidence for the role of phytochemicals as host-plant recognition templates. The project is intended to involve DNA barcoding and Bayesian phylogenetic methods, topology as well as model based methods for phylogenetic congruence testing, HPLC-DAD-SPE-NMR techniques to elucidate Rinorea phytochemicals, and behavioural experiments in the field. Currently, I am working on the molecular phylogenetics of Cymothoe using mtDNA COI and nrDNA wingless, CAD and IDH gene sequences. In addition, I am building a Cymothoe DNA barcode library in collaboration with the Canadian Centre for DNA Barcoding and a network of specialist collectors of African butterflies such as Torben Larsen, Gael vande Weghe, David Lees, Duke Knoop, Steve Collins and Steve Woodhall. The project is supervised by Freek Bakker and Marc Sosef. Collaborative contacts include Joop van Loon (Laboratory of Entomology, WUR), Niklas Wahlberg (Turku, Finland), Jerzy Jaroszewski (Copenhagen, Denmark), Gaston Achoundong (Yaoundé, Cameroon), Steph Menken (IBED, UvA) and Paul Hebert (Guelph, Canada).
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