Molecular analyses reveal consistent food web structure with elevation in rainforest Drosophila - parasitoid communities

The analysis of interaction networks across spatial environmental gradients is a powerful approach to investigate the responses of communities to global change. Using a combination of DNA metabarcoding and traditional molecular methods we built bipartite Drosophila – parasitoid food webs from six Australian rainforest sites across gradients spanning 850 m in elevation and 5°C in mean temperature. Our cost‐effective hierarchical approach to network reconstruction separated the determination of host frequencies from the detection and quantification of interactions. The food webs comprised 5–9 host and 5–11 parasitoid species at each site, and showed a lower incidence of parasitism at high elevation. Despite considerable turnover in the relative abundance of host Drosophila species, and contrary to some previous results, we did not detect significant changes to fundamental metrics of network structure including nestedness and specialisation with elevation. Advances in community ecology depend on data from a combination of methodological approaches. It is therefore especially valuable to develop model study systems for sets of closely‐interacting species that are diverse enough to be representative, yet still amenable to field and laboratory experiments

Effects of climate warming on hostparasitoid interactions

Parasitoids are key regulators of the population dynamics of their arthropod hosts, are integral to the structure and dynamics of food webs, and provide ecosystem services by suppressing agricultural pests. Despite their ecological and functional importance, relatively few studies have considered the effects of a warming climate on host-parasitoid interactions. The three primary modes through which parasitoids might respond to a warming climate are by (i) shifting distributions into cooler environments, (ii) altering phenology, and (iii) adjusting to persist in situ through phenotypic plasticity or evolutionary adaptation. Here, we focus on examples of altered distributions and phenology in response to climate warming. We suggest that the responses of parasitoids to elevated temperatures and the population dynamic consequences for their hosts will be linked to two key traits: the dispersal ability of both partners, and the host specificity of parasitoids. Effects of climate warming on host-parasitoid interactions will be complicated by interactions with other co-occurring environmental changes, such as elevated carbon dioxide and nitrogen, and to interactions with competitors, mutualists, and antagonists. These factors will complicate efforts to generate predictive models of host-parasitoid interactions, for example in the context of the ecosystem service of biological pest control. © 2013 The Royal Entomological Society

Molecular analyses reveal consistent food web structure with elevation in rainforest Drosophila – parasitoid communities

The analysis of interaction networks across spatial environmental gradients is a powerful approach to investigate the responses of communities to global change. Using a combination of DNA metabarcoding and traditional molecular methods we built bipartite Drosophila – parasitoid food webs from six Australian rainforest sites across gradients spanning 850 m in elevation and 5°C in mean temperature. Our cost-effective hierarchical approach to network reconstruction separated the determination of host frequencies from the detection and quantification of interactions. The food webs comprised 5–9 host and 5–11 parasitoid species at each site, and showed a lower incidence of parasitism at high elevation. Despite considerable turnover in the relative abundance of host Drosophila species, and contrary to some previous results, we did not detect significant changes to fundamental metrics of network structure including nestedness and specialisation with elevation. Advances in community ecology depend on data from a combination of methodological approaches. It is therefore especially valuable to develop model study systems for sets of closely-interacting species that are diverse enough to be representative, yet still amenable to field and laboratory experiment

Growth of GaN layers on GaAs and GaP (111) and (001) substrates by molecular beam epitaxy

Films of GaN have been grown using a modified MBE technique in which the active nitrogen is supplied from an RF plasma source. Wurtzite films grown on (001) oriented GaAs substrates show highly defective, ordered polycrystalline growth with a columnar structure, the (0001) planes of the layers being parallel to the (001) planes of the GaAs substrate. Films grown using a coincident As flux, however, have a single crystal zinc-blende growth mode. They have better structural and optical properties. To improve the properties of the wurtzite films we have studied the growth of such films on (111) oriented GaAs and GaP substrates. The improved structural properties of such films, assessed using X-ray and TEM method, correlate with better low-temperature FL

Thigh-length compression stockings and DVT after stroke

Controversy exists as to whether neoadjuvant chemotherapy improves survival in patients with invasive bladder cancer, despite randomised controlled trials of more than 3000 patients. We undertook a systematic review and meta-analysis to assess the effect of such treatment on survival in patients with this disease