This research provides the first evidence of dispersal of bryophytes and associated microorganisms through ingestion by a highly mobile vertebrate vector, the spectacled flying fox (Pteropus conspicillatus). Bryophyte fragments were found in faeces collected at four P. conspicillatus' camps in the Wet Tropics bioregion, northeastern Australia. These fragments were viable when grown in culture; live invertebrates and other organisms were also present. Our study has significantly increased understanding of the role of flying foxes as dispersal vectors in tropical forests.
The diet of Pteropus conspicillatus, a large flying fox, was examined by collecting faeces in traps beneath daytime roost trees in four geographically distinct camps in the Wet Tropics bioregion of North-eastern Queensland, Australia. Faecal analyses revealed that P. conspicillatus utilise a broad variety of plant resources from a variety of habitats. Seed and pulp from figs (Ficus spp., Moraceae) and pollen from the family Myrtaceae were most frequently represented in the faeces from a range of both wet sclerophyll and rainforest habitats. The dietary composition of P. conspicillatus at individual camps could not be predicted by the habitats located within a typical foraging distance of each camp (20 km), and although consistent dietary changes were seen across all camps over time, each camp had a unique dietary signature indicative of feeding on a distinct subset of available vegetation. The unique diet of each camp and the variety of dietary items consumed suggest that camps may need to be managed on an individual camp-specific basis, and that P. conspicillatus are utilising a broader range of resources than would be expected if the species was a strict ‘rainforest-fruit specialist’.
Summary Understanding spatial and environmental drivers of undisturbed stream assemblages is important for separating natural and human‐induced changes, but has rarely been attempted for an entire tropical bioregion. We sampled riffle macroinvertebrate assemblages and measured associated biophysical variables in post‐wet and dry seasons from 68 streams of orders 1–5 across the Australian Wet Tropics, a small bioregion (18 497 km2) defined by its warm moist climate and closed‐forest vegetation. As climate and landscape were relatively uniform across the bioregion, we predicted that assemblages would be similar, with turnover (beta diversity) unrelated to distance, and with composition determined mainly by habitat. We identified 93 higher taxa. Density and richness of macroinvertebrates were greatest in the dry season because of habitat contraction and minimal flow disturbance. Richness was greatest in higher order streams. Relative abundance and richness of functional groups showed minor effects of catchment, lithology and stream order, and a positive relationship with altitude for richness of collectors, predators and shredders, and for abundance of shredders. Distance‐based linear modelling showed that among‐assemblage differences were explained by landscape‐scale variables (9.5% of the variation), stream size (13.0%), riparian characteristics (9.6%), water quality (4.6%), substratum (21.1%) and organic resources (22.4%); for models of individual taxa and functional groups, habitat and organic‐resource variables also predominated. Similarities among site assemblages differed little among catchments and there was no relationship between pairwise similarities of catchments and their geographical distances. Nestedness analysis confirmed that samples and catchment groupings were nested subsets of the total set of samples. Across the Australian Wet Tropics, uniformity of assemblages (identified to family or above) conformed to the bioregional classification, probably as a result of the great age of the region. The habitat variables that most influenced macroinvertebrate assemblages support the idea that a suite of biophysical influences is common to stream macroinvertebrate assemblages globally.
Final-instar larvae of the microcaddisfly, Scelotrichia willcairnsi sp. nov. (Trichoptera: Hydroptilidae) were discovered feeding on a moss, Platyhypnidium muelleri in north-eastern Queensland. Not only do the larvae feed on the moss, but their cases are constructed from fragments of moss leaves. Microscopic examination of larval guts and cases showed a total contrast in the angle at which the moss leaves are cut for each purpose: for cases the moss leaves are cut longitudinally, in parallel with the length of the cells, whereas for feeding the leaves are cut perpendicular to the leaf margin, across the cells, presumably an adaptation that releases the cell contents for digestion. The new caddisfly species is described based on the adult males. Scelotrichia willcairnsi represents the first Australian record of the South-east Asian-New Guinean Stactobiini genus Scelotrichia.
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