An ‘ameridelphian’ marsupial from the early Eocene of Australia supports a complex model of Southern Hemisphere marsupial biogeography

Recent molecular data strongly support the monophyly of all extant Australian and New Guinean marsupials (Eomarsupialia) to the exclusion of extant South American marsupials. This, together with available geological and fossil evidence, has been used to argue that the presence of marsupials in Australia is simply the result of a single dispersal event from South America during the latest Cretaceous or Palaeocene, without subsequent dispersals between the two continents. Here, I describe an isolated ankle bone (calcaneus) of a metatherian from the early Eocene Tingamarra Local Fauna in northeastern Australia. Strikingly, this specimen, QM F30060, lacks the ‘continuous lower ankle joint pattern’ (CLAJP), presence of which is a highly distinctive apomorphy of the marsupial clade Australidelphia, which includes Eomarsupialia, the living South American microbiotherian Dromiciops and the Tingamarran fossil marsupial Djarthia. Comparisons with a range of marsupials and stem-metatherians strongly suggest that the absence of the CLAJP in QM F30060 is plesiomorphic, and that this specimen represents the first unequivocal non-australidelphian (‘ameridelphian’) metatherian known from Australia. This interpretation is confirmed by phylogenetic analyses that place QM F30060 within (crown-group) Marsupialia, but outside Australidelphia. Based on these results, the distribution of marsupials within Gondwana cannot be explained by simply a single dispersal event from South America and Australia. Either there were multiple dispersals by marsupials (and possibly also stem-metatherians) between South America and Australia, in one or both directions, or, alternatively, there was a broadly similar metatherian fauna stretching across southern South America, Antarctica and Australia during the Late Cretaceous–early Palaeogene.     

Commuting lives: children's mobility and energy use

Globally, the issue of energy use and climate change is at the forefront of many national and international agendas, and also an issue central to children's lives and well-being. This paper examines how children are both affected by and contribute to the problems associated with unsustainable energy use as it relates to the growth of car dependent lives. The paper presents the findings of a study of travel as it relates to the everyday lives of children in the city of Dunedin in New Zealand. The study found that children currently lead complex car dependent lives. This extensive car reliance presents a serious and largely unrecognised challenge to the sustainable planning and management of the urban environment. The move towards more sustainable transportation can bring benefits for both the environment and for children's lives.     

MAKING SMARTER ENVIRONMENTAL MANAGEMENT DECISIONS1

ABSTRACT: This paper outlines a sound, practical approach for making more informed decisions about environmental policy choices. It emphasizes the importance of using a structured decision process to specify and organize values, use these values to create alternatives, and assess tradeoffs to help achieve a desired balance across key objectives. Although these decision making steps are based on common sense, they are often neglected or poorly carried out as part of the complex evaluations of natural resource options. We discuss several reasons for this frequent neglect of decision making principles and provide examples from recent water use planning projects to demonstrate some of the benefits of using a structured, decision focused approach: new and better solutions, increased and more productive participation by stakeholders, and greater defensibility and acceptance of the resource management evaluation process and its conclusions.     

Performing a regulatory compliance audit: Guidance for environmental managers

An important tool for managing environmental responsibilities is compliance auditing. Auditing the facility allows the environmental manager to identify problems, address potential violations, and streamline environmental compliance expenditures. However, the audit and associated program must be developed within the context of immediate and long-term goals. Before initiating the physical audit, the environmental manager should identify the scope of the audit, select a team, establish the audit process, and decide on report documentation issues, such as confidentiality. If the audit program is developed correctly, todays environmental manager can streamline long-term compliance while managing the company's liability.     

Response of “Alamo” switchgrass tissue chemistry and biomass to nitrogen fertilization in West Tennessee,USA

Switchgrass (Panicum virgatum) is a perennial, warm-season grass that has been identified as a potential biofuel feedstock over a large part of North America. We examined above- and belowground responses to nitrogen fertilization in “Alamo” switchgrass grown in West Tennessee, USA. The fertilizer study included a spring and fall sampling of 5-year old switchgrass grown under annual applications of 0, 67, and 202 kg N ha^?1 (as ammonium nitrate). Fertilization changed switchgrass biomass allocation as indicated by root:shoot ratios. End-of-growing season root:shoot ratios (mean ± SE) declined significantly (P ≤ 0.05) at the highest fertilizer nitrogen treatment (2.16 ± 0.08, 2.02 ± 0.18, and 0.88 ± 0.14, respectively, at 0, 67, and 202 kg N ha^?1). Fertilization also significantly increased above- and belowground nitrogen concentrations and decreased plant C:N ratios. Data are presented for coarse live roots, fine live roots, coarse dead roots, fine dead roots, and rhizomes. At the end of the growing season, there was more carbon and nitrogen stored in belowground biomass than aboveground biomass. Fertilization impacted switchgrass tissue chemistry and biomass allocation in ways that potentially impact soil carbon cycle processes and soil carbon storage.     

A framework to assess regional environmental impacts of dedicated energy crop production

Numerous studies have evaluated air quality and greenhouse gas mitigation benefits of biomass energy systems, but the potential environmental impacts associated with large-scale changes in land-use patterns needed to produce energy crops have not been quantified. This paper presents a framework to assess the potential soil, water, and biodiversity impacts that may result from the large-scale production of dedicated energy crops. The framework incorporates producer economic decision models with environmental models to assess changes in land use patterns and to quantify the consequent environmental impacts. Economic and policy issues that will affect decisions to produce energy crops are discussed. The framework is used to evaluate erosion and chemical runoff in two Tennessee regions. The analysis shows that production of dedicated energy crops in place of conventional crops will significantly reduce erosion and chemical runoff.     

Transient nestmate recognition cues contribute to a multicolonial population structure in the ant,Leptothorax curvispinosus

Summary Individual nests of the facultatively polygynous and polydomous ant, Leptothorax curvispinosus, were mapped at two sites, collected, and maintained under uniform laboratory conditions. Tests of worker acceptability between nests were conducted 2–4 weeks and 13–17 weeks after collection. Nests collected near to one another (0.09–1.87 m) were sometimes nonaggressive, and were significantly less aggressive than those from different sites (7 km apart); and there was no significant difference in aggressiveness between tests for these distance categories. However, aggression between nests collected farther away from one another at the same site (1.52–4.65 m) decreased significantly between tests: initially, the level of aggressiveness was equivalent to that between nests from different sites but later it was reduced to that between near nests. These results indicate that polydomous colonies of this species occur within multicolonial populations; and that colony segregation within local populations is largely maintained by transient environmentally-based nestmate recognition cues. More stable cues of genetic or environmental origin (or both) are also present and contribute to discrimination even after extended periods of culture under uniform conditions. These results suggest that the maintenance of colony autonomy within genetically highly interrelated populations may be the prime function of environmentally-based nestmate recognition cues. Colony autonomy under such circumstances may be important to maintain a relatively small but optimal colony size, or because the mechanisms which regulate colony growth, development, etc., require a limited colony size.     

Contrasting structure and composition of the understory in species-rich tropical rain forests

In large samples of trees > or = 1 cm dbh (more than 1 million trees and 3000 species), in six lowland tropical forests on three continents, we assigned species with >30 individuals to one of six classes of stature at maturity (SAM). We then compared the proportional representation of understory trees (1-2 cm dbh) among these classes. The understory of the three Asian sites was predominantly composed of the saplings of large-canopy trees whereas the African and American sites were more richly stocked with trees of the smaller SAM classes. Differences in class representation were related to taxonomic families that were present exclusively in one continent or another. Families found in the Asian plots but not in the American plot (e.g., Dipterocarpaceae, Fagaceae) were predominantly species of the largest SAM classes, whereas families exclusive to the American plots (e.g., Melastomataceae sensu stricto, Piperaceae, and Malvaceae [Bombacacoidea]) were predominantly species of small classes. The African plot was similar to Asia in the absence of those American families rich in understory species, while similar to America in lacking the Asian families rich in canopy species. The numerous understory species of Africa were chiefly derived from families shared with Asia and/or America. The ratio of saplings (1-2 cm dbh) to conspecific canopy trees (>40 cm dbh) was lower in American plots than in the Asian plots. Possible explanations for these differences include phenology, moisture and soil fertility regimes, phyletic constraints, and the role of early successional plants in forest development. These results demonstrate that tropical forests that appear similar in tree number, basal area, and the family taxonomy of canopy trees nonetheless differ in ecological structure in ways that may impact the ecology of pollinators, dispersers, and herbivores and might reflect fundamental differences in canopy tree regeneration.