Network reorganization and breakdown of an ant-plant protection mutualism with elevation.

Both the abiotic environment and the composition of animal and plant communities change with elevation. For mutualistic species, these changes are expected to result in altered partner availability, and shifts in context-dependent benefits for partners. To test these predictions, we assessed the network structure of terrestrial ant-plant mutualists and how the benefits to plants of ant inhabitation changed with elevation in tropical forest in Papua New Guinea. At higher elevations, ant-plants were rarer, species richness of both ants and plants decreased, and the average ant or plant species interacted with fewer partners. However, networks became increasingly connected and less specialized, more than could be accounted for by reductions in ant-plant abundance. On the most common ant-plant, ants recruited less and spent less time attacking a surrogate herbivore at higher elevations, and herbivory damage increased. These changes were driven by turnover of ant species rather than by within-species shifts in protective behaviour. We speculate that reduced partner availability at higher elevations results in less specialized networks, while lower temperatures mean that even for ant-inhabited plants, benefits are reduced. Under increased abiotic stress, mutualistic networks can break down, owing to a combination of lower population sizes, and a reduction in context-dependent mutualistic benefits

Spatial covariance of herbivorous and predatory guilds of forest canopy arthropods along a latitudinal gradient

In arthropod community ecology, species richness studies tend to be prioritised over those investigating patterns of abundance. Consequently, the biotic and abiotic drivers of arboreal arthropod abundance are still relatively poorly known. In this cross-continental study, we employ a theoretical framework in order to examine patterns of covariance among herbivorous and predatory arthropod guilds. Leaf-chewing and leaf-mining herbivores, and predatory ants and spiders, were censused on > 1000 trees in nine 0.1 ha forest plots. After controlling for tree size and season, we found no negative pairwise correlations between guild abundances per plot, suggestive of weak signals of both inter-guild competition and top-down regulation of herbivores by predators. Inter-guild interaction strengths did not vary with mean annual temperature, thus opposing the hypothesis that biotic interactions intensify towards the equator. We find evidence for the bottom-up limitation of arthropod abundances via resources and abiotic factors, rather than for competition and predation.publishedVersio

Plant-herbivore interactions along ecological gradients in tropical rainforest: Drivers of network structure and specialisation

This thesis concerns the community ecology of Lepidopteran herbivores and their host plants in rainforests of Papua New Guinea. We specifically focus on examining the drivers of plant-herbivore interaction network structure and herbivore specialisation across rainforest succession and elevation. Using one of the most comprehensive and unique datasets of its kind, gathered using a 'whole forest' approach, we investigate how networks are structured in young secondary, mature secondary and primary forest. Furthermore, we revisit a classic ecological question, exploring specialisation of herbivores and how abiotic and biotic factors might influence this. We show that an understanding of host community properties including phylogeny, physical structure and theorised defensive investment can be used to explain interaction network structure. We also find that specialisation changes with elevation, guild type and habitat use in ways which are difficult to predict. We finish by analysing and presenting our relatively novel methodological approach. It is our hope that it can gain wider adoption thus facilitating broader comparative studies

Yawan_Tree_Phylogeny

A Newick file of the Host Tree Phylogeny used for analysis of host community phylogenetic diversity and Distance Based Specialisation Index (DSI

Quantitative Plant-Herbivore interaction matrices

Nine txt files with quantitative interaction matrices. Files ABCD-Primary forest plots, HJK-Mature secondary forest plots and FG- Young secondary forest plot

Automatic detection of paroxysmal atrial fibrillation

The purpose of this chapter is to provide a tutorial level introduction to (a) the physiology and clinical background of paroxysmal (intermittent) atrial fibrillation (PAF), and (b) methods for detection of patterns consistent with AF using electrocardiogram (ECG) processing. The document assumes that the reader is familiar with basic signal processing concepts, but assumes no prior knowledge of AF or pattern classification. A practical implementation of an automatic AF detector is presented; a supervised linear discriminant classifier is used to estimate the likelihood of a block of inter-heartbeat intervals being PAF, with accuracies of 92%, 94%, 100% and 100% when the method was used to process the publically available Physionet (Goldberger et al., 2000) signal databases MITDB, AFDB, NSRDB and NSR2DB respectively

2. Behaviour analysis

R code for behavioural experimen