Pollen transport and deposition in riverine and marine environments within the humid tropics of northeastern Australia

Mechanisms of pollen transport in the humid tropics region of northeastern Australia were investigated to support the interpretation of a long Quaternary pollen record from ODP Site 820 located on the adjacent continental slope. Pollen analysis of surface sediment samples from the channels of two major river catchments demonstrated internal consistency in pollen spectra and little fluvial pollen sorting in relation to sediment variation. Differences in modem pollen spectra between catchments reflect existing variation in vegetation cover that, in turn, reflects climatic differences between catchments. Recent pollen spectra from top samples of the ODP core have sufficient in common with the riverine samples to suggest that the rivers are contributing a major pollen component to the offshore sediments, but these have been size sorted by marine action. Recent pollen samples from core tops taken from the Grafton Passage on the continental shelf that was thought to be the major passage for pollen transport to ODP Site 820 show significant differences to both riverine and ODP samples and suggest that pollen are dispersed across the continental shelf and through the outer Great Barrier Reef system in a more complex way than anticipated. (c) 2004 Elsevier B.V. All rights reserved.

Division of labour within cooperatively breeding groups

Within cooperative societies, group members share in caring for offspring. Although division of labour among group members has been relatively well studied in insects, less is known about vertebrates. Most studies of avian helping focus solely on the extent to which helpers provision the offspring, however, helpers can participate in everything from nest building to predator defence. Bad provisioners may, for example, not be as 'uncooperative' as they appear. if they are good defenders. Thus, the distribution of helping tasks between group members should have important implications for our interpretation of group dynamics. Here, we compare two distinct forms of helping behaviour in the cooperatively breeding noisy miner (Manorina melanocephala): chick provisioning and mobbing nest predators. We show that the way in which individual helpers invest in these two helping behaviours varies enormously across individuals and among social groups. Good provisioners often contributed relatively little to mobbing and vice versa. Indeed, (18%) of helpers only mobbed, 22% just provisioned, whereas 60% of helpers performed both forms of helping. Across nests, provisioning was significantly negatively correlated with mobbing effort. We suggest that small differences in the costs or benefits of different aspects of helping (due to differences in age, relatedness or social status) have a big impact on the division of labour within a group. Consequently, social groups can be made up from individuals who often specialise in one helping behaviour, and/or helpers who perform a number of behaviours to differing degrees. Division of labour within social groups will, therefore, have important consequences for the maintenance of cooperatively breeding in vertebrates.

“Doing” Gender in Context: Household Bargaining and Risk of Divorce in Germany and the United States

Gender relations remain embedded in their sociopolitical context. Compared here using event-history analysis is how household divisions of paid and unpaid labor affect marital stability in the former West Germany, where policy reinforced male breadwinner families, and the United States, where policy remains silent regarding the private sphere. In Germany, any moves away from separate gendered spheres in terms of either wives' relative earnings or husbands' relative participation in housework increase the risk of divorce. In the United States, however, the more stable couples are those that adapt by displaying greater gender equity. These results highlight that policy shapes how gender gets done in the intimate sphere, and that reinforcement of a gendered division of labor may be detrimental to marital stability.

Holocene depositional history of the Burdekin River delta of northeastern Australia: A model for a low-accommodation, highstand delta

The Burdekin River of northeastern Australia has constructed a substantial delta during the Holocene (delta plain area 1260 km2). The vertical succession through this delta comprises (1) a basal, coarse-grained transgressive lag overlying a continental omission surface, overlain by (2) a mud interval deposited as the coastal region was inundated by the postglacially rising sea, in turn overlain by (3) a generally sharp-based sand unit deposited principally in channel and mouth-bar environments with lesser volumes of floodplain and coastal facies. The Holocene Burdekin Delta was constructed as a series of at least thirteen discrete delta lobes, formed as the river avulsed. Each lobe consists of a composite sand body typically 5-8 m thick. The oldest lobes, formed during the latter stages of the postglacial sea-level rise (10-5.5 kyr BP), are larger than those formed during the highstand (5.5-3 kyr BP), which are in turn larger than those formed during the most recent slight sea-level lowering and stillstand (3-0 kyr BP). Radiocarbon ages and other stratigraphic data indicate that inter-avulsion period has decreased through time coincident with the decrease in delta lobe area. The primary control on Holocene delta architecture appears to have been a change from a pluvial climate known to characterize the region 12-4 kyr BP to the present drier, ENSO-dominated climate. In addition to decreasing the sediment supply via lower rates of chemical weathering, this change may have contributed to the shorter avulsion period by facilitating extreme variability of discharge. More frequent avulsion may also have been facilitated by the lengthening of the delta-plain channels as the system prograded seaward. Copyright © 2006, SEPM (Society for Sedimentary Geology).

Polyethism and comparability of termite choice assays in a model system using Microcerotermes turneri (Termitidae : Termitinae): Implications for standardised testing techniques

Traditional measures of termite food preference assess consequences of foraging behavior such as wood consumption, aggregation and/or termite survivorship. Although studies have been done to investigate the specifics of foraging behavior this is not generally integrated into choice assay experiments. Here choice assays were conducted with small isolated (orphaned) groups of workers and compared with choice assays involving foragers from whole nests (non-orphaned) in the laboratory. Aggregation to two different wood types was used as a measure of preference. Specific worker caste and instars participating in initial exploration were compared between assay methods, with samples of termites taken from nest carton material and sites where termites were feeding. Aggregation results differ between choice assay techniques. Castes and instars responsible for initial exploration, as determined in whole nest trials, were not commonly found exploring in isolated group trials, nor were they numerous in termites taken from active feeding sites. Consequently the use of small groups of M. turneri worker termites extracted from active feeding sites may not be appropriate for use in choice assays.

Modelling pre-clearing vegetation distribution using GIS-integrated statistical, ecological and data models: A case study from the wet tropics of Northeastern Australia

Traditional vegetation mapping methods use high cost, labour-intensive aerial photography interpretation. This approach can be subjective and is limited by factors such as the extent of remnant vegetation, and the differing scale and quality of aerial photography over time. An alternative approach is proposed which integrates a data model, a statistical model and an ecological model using sophisticated Geographic Information Systems (GIS) techniques and rule-based systems to support fine-scale vegetation community modelling. This approach is based on a more realistic representation of vegetation patterns with transitional gradients from one vegetation community to another. Arbitrary, though often unrealistic, sharp boundaries can be imposed on the model by the application of statistical methods. This GIS-integrated multivariate approach is applied to the problem of vegetation mapping in the complex vegetation communities of the Innisfail Lowlands in the Wet Tropics bioregion of Northeastern Australia. The paper presents the full cycle of this vegetation modelling approach including sampling sites, variable selection, model selection, model implementation, internal model assessment, model prediction assessments, models integration of discrete vegetation community models to generate a composite pre-clearing vegetation map, independent data set model validation and model prediction's scale assessments. An accurate pre-clearing vegetation map of the Innisfail Lowlands was generated (0.83r(2)) through GIS integration of 28 separate statistical models. This modelling approach has good potential for wider application, including provision of. vital information for conservation planning and management; a scientific basis for rehabilitation of disturbed and cleared areas; a viable method for the production of adequate vegetation maps for conservation and forestry planning of poorly-studied areas. (c) 2006 Elsevier B.V. All rights reserved.

Construction of an Intraplate Fault System Model of South Australia, and Simulation Tool for the iSERVO Institute Seed Project

To foster ongoing international cooperation beyond ACES (APEC Cooperation for Earthquake Simulation) on the simulation of solid earth phenomena, agreement was reached to work towards establishment of a frontier international research institute for simulating the solid earth: iSERVO = International Solid Earth Research Virtual Observatory institute (http://www.iservo.edu.au). This paper outlines a key Australian contribution towards the iSERVO institute seed project, this is the construction of: (1) a typical intraplate fault system model using practical fault system data of South Australia (i.e., SA interacting fault model), which includes data management and editing, geometrical modeling and mesh generation; and (2) a finite-element based software tool, which is built on our long-term and ongoing effort to develop the R-minimum strategy based finite-element computational algorithm and software tool for modelling three-dimensional nonlinear frictional contact behavior between multiple deformable bodies with the arbitrarily-shaped contact element strategy. A numerical simulation of the SA fault system is carried out using this software tool to demonstrate its capability and our efforts towards seeding the iSERVO Institute.

The graying of R&D workgroups: The effects of age diversity on developing publicly usable knowledge

Does the graying of scientific research teams matter? This study addresses how workgroup processes and external environmental factors contribute and inhibit the effect of age diversity in R&D project groups on the production of innovative publicly usable knowledge outcomes in the form of publication outputs. We examined the relationships between group age diversity (age cohort diversity, mean age, age dispersion), R&D workgroup member self-ratings of workgroup processes, their supervisor�s assessment of the external environmental factors the project groups faced, and their supervisor�s ratings of group performance, the number of scientific publicly available publications produced by the group and the use of multiple authorships on publications. Usable data was obtained from 32 R&D workgroups of a large Government Agricultural Research and Development Agency. Consistent with the literature, workgroup processes and external environmental factors were found to directly effect innovation outcomes. Contrary to expectation, but consistent with Social Identity theory, workgroup age diversity generally negatively impacted upon innovation outcomes. An exception was where multiple authorship on publications for project groups increased as the dispersion of age within groups increased. Importantly, workgroups that were both more age homogeneous and perceived to have optimally functioning work processes produced more R&D innovation outcomes than other groups. Generally, these differences appear to be related to the greater division of labor practices (and less multi-tasking) employed by the older and more homogeneous workgroups. Implications for R&D workgroup resource theory and practices are discussed.