We describe a well-preserved pelvis from the Maastrichtian S^anpetru Formation of the Hat¸ eg Basin in Romania. The fossil closely resembles the pelvis of Gargantuavis philoinos from the Ibero-Armorican Peninsula, but differs in a smaller size and a few morphological features. It constitutes the first record of Gargantuavis outside the Ibero-Armorican Island and is more complete than any of the previously known Gargantuavis pelves. The new fossil allows the recognition of characteristics previously unknown for Gargantuavis. These include the presence of large supratrochanteric processes, the absence of a widened midsection of the synsacrum (which indicates the absence of a glycogen body), and the absence of fusion between the pelvic bones at the level of the acetabulum. The latter two features suggest that Gargantuavis is not closely related to the Ornithurae and the taxon may even fall outside the Ornithothoraces, the clade including Enantiornithes and Ornithuromorpha. Recognition of Gargantuavis in the fauna of the Hat¸ eg Island is of particular significance, because various theropods have been described from the Upper Cretaceous of Romania. The Romanian pelvis is of similar size to Elopteryx nopcsai, which was described as avian and is based on hindlimb elements, and it also shows some similarities to the pelvis of the unusual theropod Balaur bondoc. The new fossil furthermore disproves the hypothesis that the flight capabilities of Gargantuavis were lost in an insular environment of the Ibero-Armorican Island, and raises the possibility that Gargantuavis, Elopteryx, and Balaur belong to a distinctive theropod clade of the Late Cretaceous European archipelago.
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RBINS Staff Publications 2018
Generalist arthropod herbivores rapidly adapt to a broad range of host plants. However, the extent of transcriptional reprogramming in the herbivore and its hosts associated with adaptation remains poorly understood. Using the spider mite Tetranychus urticae and tomato as models with available genomic resources, we investigated the reciprocal genomewide transcriptional changes in both spider mite and tomato as a consequence of mite's adaptation to tomato. We transferred a genetically diverse mite population from bean to tomato where triplicated populations were allowed to propagate for 30 generations. Evolving populations greatly increased their reproductive performance on tomato relative to their progenitors when reared under identical conditions, indicative of genetic adaptation. Analysis of transcriptional changes associated with mite adaptation to tomato revealed two main components. First, adaptation resulted in a set of mite genes that were constitutively downregulated, independently of the host. These genes were mostly of an unknown function. Second, adapted mites mounted an altered transcriptional response that had greater amplitude of changes when re-exposed to tomato, relative to nonadapted mites. This gene set was enriched in genes encoding detoxifying enzymes and xenobiotic transporters. Besides the direct effects on mite gene expression, adaptation also indirectly affected the tomato transcriptional responses, which were attenuated upon feeding of adapted mites, relative to the induced responses by nonadapted mite feeding. Thus, constitutive downregulation and increased transcriptional plasticity of genes in a herbivore may play a central role in adaptation to host plants, leading to both a higher detoxification potential and reduced production of plant defence compounds.
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