Mutualistic networks display distinct structural and organizational features such as nestedness, powerlaw degree distribution and asymmetric dependencies. Attention is now focused on how these structural properties influence network function. Most plant-pollinator networks are constructed using records of animals contacting flowers, which is based on the assumption that all visitors to flowers are pollinators; however, animals may visit flowers as nectar robbers, florivores, or to prey upon other visitors.To differentiate potential pollinator interactions from other interaction types, we examined individual bees that had visited flowers to detect if they carried pollen. Using these data, we constructed visitation and pollen-transport networks for a spinifex-dominated arid zone grassland. To determine how the structure of the visitation network reflects pollen transport, we compared the two networks using a null model approach to account for differences in network size. Differences in number of species, nestedness and connectance observed between the visitation and pollen-transport networks were within expected ranges generated under the null model.The pollen-transport network was more specialized, had lower interaction evenness, and fewer links compared to the visitation network. Almost half the number of species of the visitation network participated in the pollen-transport network, and one-third of unique visitation interactions resulted in pollen transport, highlighting that visitation does not always result in pollination. Floral visitor data indicate potential pollen transporters, but inferring pollination function from visitation networks needs to be performed cautiously as pollen transport resulted from both common and rare interactions, and depended on visitor identity. Although visitation and pollen-transport networks are structurally similar, the function of all species cannot be predicted from the visitation network alone. Considering pollen transport in visitation networks is a simple first step towards determining pollinators from non-pollinators. This is fundamental for understanding how network structure relates to network function.

Methods for sampling ecological assemblages strive to be efficient, repeatable, and representative. Unknowingly, common methods may be limited in terms of revealing species function and so of less value for comparative studies. The global decline in pollination services has stimulated surveys of flower-visiting invertebrates, using pan traps and net sampling. We explore the relative merits of these two methods in terms of species discovery, quantifying abundance, function, and composition, and responses of species to changing floral resources. Using a spatially-nested design we sampled across a 5000 km2 area of arid grasslands, including 432 hours of net sampling and 1296 pan trap-days, between June 2010 and July 2011. Net sampling yielded 22% more species and 30% higher abundance than pan traps, and better reflected the spatio-temporal variation of floral resources. Species composition differed significantly between methods; from 436 total species, 25% were sampled by both methods, 50% only by nets, and the remaining 25% only by pans. Apart from being less comprehensive, if pan traps do not sample flower-visitors, the link to pollination is questionable. By contrast, net sampling functionally linked species to pollination through behavioural observations of flower-visitation interaction frequency. Netted specimens are also necessary for evidence of pollen transport. Benefits of net-based sampling outweighed minor differences in overall sampling effort. As pan traps and net sampling methods are not equivalent for sampling invertebrate-flower interactions, we recommend net sampling of invertebrate pollinator assemblages, especially if datasets are intended to document declines in pollination and guide measures to retain this important ecosystem service.

Abstract. Five new species of Leioproctus (Protomorpha) Rayment from western Queensland are described: Leioproctus crispus n.sp., L. gibber n.sp., L. gurneyi n.sp., L. latifrons n.sp. and L. nix n.sp. Females of all the new species, except L. nix, have specialized setae on the clypeus, frons or vertex of the head. A revised key to species is provided. In the most recent revision of the subgenus Leioproctus (Protomorpha) (Maynard, 1991), nine species were recognized, but only five were named. The remaining four were known from females only. In a recent study of plant-pollinator networks in the arid-zone grassland of the north-eastern Simpson Desert (Popic et al., 2013), seven L. (Protomorpha) species were found, five of them undescribed. Four of the new species are the first in the subgenus to have specialized hairs on the head, a feature that has been suggested as indicative of particular pollen collecting behaviour (

We argue here that climate change studies which focus only on single species will be inadequate to address the complexity of causal mechanisms, as climate effects will percolate through entire ecological communities. Changes in species distributions may be considered as: 1) fully independent, in which case each species will respond directly to environmental factors; 2) dependent upon a set of biological interactions among species; or 3) of a combination of both environmental and biological factors. Our second point is that climate extremes will drive substantial change beyond any changes in averages-and that it is these rare outlier events that are most likely to be relevant for Australia and for the arid zone in particular. A corollary of this point is that at present, the extremes, e.g. rainfall in the arid zone, are currently unpredictable and this unpredictability is likely to further increase as the extremes increase. This could lead to events of greater severity, more frequent extreme events of current magnitude, or a combination of both. It is not known to what extent the Southern Oscillation Index and the El Niño/ La Niña cycles will be altered. We illustrate our case by considering the interactions among flowering plants and their floral visitors in the Simpson Desert.

Animals visit flowers to access resources and by moving pollen to conspecific individuals act as pollinators. While biotic pollinators can increase the seed set of plants, other flower visitors can reduce seed set directly by damaging vital reproductive organs and indirectly by affecting the way the plant interacts with subsequent flower visitors. It is, therefore, vital to understand the varied effects of all visitors and not only pollinators on plant fitness, including those visitors that are temporally or spatially rare. We document the first known case of flower visitation by small mammals to Crotalaria cunninghamii (Fabaceae), a plant species morphologically suited to bird pollination. During a rain-driven resource pulse in the Simpson Desert in 2011, the rodents Mus musculus (Muridae) and Pseudomys hermannsburgensis (Muridae) visited flowers to remove nectar by puncturing the calyx. We investigated the effects of this novel interaction on the reproductive output of C. cunninghamii. Compared with another recent resource pulse in 2007, plants flowering during mammal visitation had five times as many inflorescences per plant, 90% more flowers per inflorescence, and two to three times more nectar per flower, but this nectar was 30% less sugar rich. Concurrently, rodent plagues were up to three times larger during this rain-driven resource pulse than during a previous pulse in 2007. Up to 75% of flowers had evidence of small mammal florivory, but this was not necessarily destructive, as up to 90% of fruit had the remains of florivory. Through a series of exclusion experiments, we found that small mammal florivory did not directly reduce seed set. We conclude that rain-driven resource pulses led to a unique combination of events that facilitated the novel florivory interaction. Our findings emphasize the dynamic nature of biotic interactions and the importance of testing the role of all visitors to pollination services.