TABLE CONTENTS

Evolution of Feeding Types and Plant-Parasitism in Tylenchina
(Nematoda: Rhabditida): Different Constraints Compared to Feedingindependent
Structures
Bert, W. (1), F. Leliaert (2), A.R. Vierstraete (3), J.R. Vanfleteren (3) & G. Borgonie (1)
(1) Nematology section, Department of Biology, Ghent University, Ledeganckstraat 35, 9000 Ghent,
Belgium; (2) Phycology Research Group and Centre for Molecular Phylogenetics and Evolution,
Department of Biology, Ghent University, Krijgslaan 281 S8, 9000 Ghent, Belgium; (3) Research
Group Aging Physiology and Molecular Evolution, Department of Biology, Ghent University,
Ledeganckstraat 35, 9000 Ghent, Belgium
Tylenchina are a morphologically and functionally diverse group of nematode species that
range from free-living bacteriovores, over transitory grazing root-hair feeders to highly
specialized plant-parasites with complex host associations. We performed phylogenetic
analyses of small subunit rDNA sequences from 97 species including an analysis that account
for the RNA secondary structure in the models of evolution. The present study confirms the
sister relationship of the bacteriovore Cephalobidae with the predominantly plant-parasitic
Tylenchomorpha. All analyses appoint the fungal-feeding Aphelenchidae and
Aphelenchoididae as being polyphyletic but the morphology based hypothesis of their
monophyly could not be significantly rejected. Within the Tylenchomorpha, the families that
exclusively parasitize higher plants are joined in a single clade. However, only the
monophyletic position of the (super)families Hoplolaimidae and Criconematoidea were
supported; Anguinidae Tylenchidae, Belonolaimidae and Pratylenchidae appeared to be
paraphyletic or polyphyletic. Parsimony and likelihood ancestral state reconstruction revealed
that burrowing endoparasitism and sedentary endoparasitism each evolved respectively at
least six and at least three times independently, mostly from migratory ectoparasitic
ancestors. Only root-knot nematodes have evolved from burrowing endoparasitic nematodes.
Traditional classifications are partially misled by this convergent evolution of feeding type
and associated morphology. Contrastingly, mapping attributes of the gonoduct cellular
architecture, including newly obtained data of 18 species belonging to the Aphelenchoidea,
Criconematoidea, Anguinidae and Panagrolaimidae, revealed a broad congruence of the
gonoduct characters and the molecular phylogenetic hypothesis. Yet, the proliferation of
uterus cells has evolved multiple times, associated with derived endoparasitic feeding
specialization and resulting reproduction mode. Ancestral state reconstruction further
revealed that the gonoduct of the morphologically and ecologically dissimilar tylenchid and
cephalobid nematodes evolved from a common ancestor.
Molecular Differences between Radopholus similis Isolates in Australia
Tan, M. (1), L. Cook (1), J. Cobon (2) & E. Aitken (1)
(1) The University of Queensland, St Lucia, Queensland 4066; (2) Queensland Department of Primary
Industries and Fisheries 80 Meiers Rd, Indooroopilly, Queensland 4068
Radopholus similis is one of the top ten most destructive plant-parasitic nematodes in the
world. In banana, control measures such as crop rotation, resistant cultivars, soil amendments
and chemical control can reduce nematode levels. Currently, nematicides are used, which are
potentially hazardous to the workers and the environment. Furthermore, their efficacy being
reduced due to enhanced biodegradation. In Australia, the nematode susceptible cultivar
Cavendish, constitutes 95% of the industry with the remaining 5% consisting of Lady Finger,
5 th International Congress of Nematology, 2008 188