Seminar Series Abstracts
2014 Biological Sciences Seminar Series
7 March l Dr Anna Metaxas l Dept. of Oceanography, Dalhousie University, Nova Scotia, Canada
What drives larval transport: from the beaker to the ocean
Population connectivity is one of the criteria in the design of networks of MPAs. For marine benthic invertebrates, most of which are sessile or near sessile, larval transport is a significant driver of population connectivity. However, the prediction of larval transport presents a major challenge because larvae cannot be tracked in the field. Our research measures larval behaviours in tractable laboratory experiments that can explain larval distributions observed in the field and can be included in biophysical models to predict larval transport.
2013 Seminar Series
25 October l Prof Karen Holl l University of California
Applied nucleation as a tropical forest restoration strategy
I will discuss a decade-long, large-scale forest restoration experiment in southern Costa Rica designed to compare the applied nucleation restoration approach (planting tree islands) to natural recovery (no tree planting) and mixed species tree plantations (planting the entire area with trees). The experiment is replicated at 13 sites surrounded by 10-75% forest cover. I will draw on our extensive data on seed dispersal, seedling recruitment, nutrient cycling, light conditions, and bird communities to discuss key insights into the efficacy of the different restoration approaches and the effect of the surrounding landscape on tropical forest recovery.
18 October l Dr Ben Phillips l James Cook University
Evolutionary ecology in space: toads, fire, and turkey nests
This is a talk in three parts, loosely arranged around the theme of why space matters in ecology and evolution. In the first part, I’ll talk about cane toads, their invasion across northern Australia, and how spatial effects have led to rapid evolution and accelerated invasion. I’ll then segue seamlessly into talking about spinifex, fire, and why space matters to our inference about historical fire regimes. Finally, just to keep everyone off balance, I’ll return to toads again and talk about how it may just be possible to halt their spread across northern Australia.
11 October l Dr Jim Weller l University of Tasmania
Control of flowering time in legumesThe temperate legumes are an important and ancient group of crop plants but the molecular basis for domestication and adaptation in many of these species is relatively unexplored. We are using a variety of genetic approaches to investigate these questions, examining a number of traits including flowering time, growth habit, seed dormancy and dispersal. This talk will address two of our main interests; how fundamental flowering mechanisms in legumes differ from other major crop groups, and how modification to these mechanisms has allowed adaptation to diverse eco-geographic environments and seasonal production practices.
27 September l Prof Simon Potts l School of Agriculture, Reading University, UK
Biodiversity, Ecosystem Services and Food Security
Biodiversity can provide a suite of ecosystem services underpinning food production. Using pollination as a case study, I quantify the status and trends of pollinators and look at the range of environmental pressures they face. I answer the question “who actually pollinates”, and along the way bust a long-standing myth, before demonstrating that economic approaches can help direct policies targeted at pollinators. I also look at a range of interventions for pollinator mitigation and show how their effectiveness varies with landscape context and farm type. Finally, I consider how similar approaches can be applied to pest regulation and soil services.
Centipede venom evolution: Casting light on a neglected group of venomous animals
Centipedes are among the oldest extant group of terrestrial venomous animals. However, despite being notorious for their painful stings and ferocious predatory ecology, virtually nothing is known about their venoms. Using a multi-angled approach we provide the first comprehensive insight into the composition and evolution of these ancient and unique venoms. This revealed a surprising richness of both novel and convergently recruited toxin types, but also substantial variation in toxin diversity and resulting venom strategies between taxa. Our results also highlight the biodiscovery potential of centipede venoms, and provide a first evolutionary roadmap to guide future such efforts.
6 September l A/Prof Will Rifkin l Centre for Social Responsibility in Mining, The University of Queensland
Why some Biologists get Listened to and Others Don't: the Negotiation of Expert Status
Do people heed your scientific advice, granting you ‘expert status’? Expert status is the measure of authority that people give to a scientist, physician, lawyer, or massage therapist based on a perception of the professional’s knowledge and skill. They also consider how relevant this apparent knowledge is to their concerns. When they cannot test whether the person they are listening to really knows what they are talking about – because the presumed ‘expert’ knows more than they do – they decide whether to listen based on criteria other than the speaker’s knowledge. Thus, expert status is ‘negotiated’ and provisional.
13 September l Dr Judith Reinhard l Queensland Brain Institute, The University of Queensland
Memories of odours past: floral scent learning and brain plasticity in honeybees
Pollinating insects such as honeybees have to detect, process and learn numerous different floral scents during their daily foraging trips. This olfactory environment changes constantly, requiring an adaptive and plastic response from foraging bees. How is this plasticity achieved in the sensory periphery where the odours are detected, and in the higher brain centres where odour memories are laid down? This talk will explore some of the emerging neural and molecular mechanisms underlying sensory and brain plasticity in honeybees. We will demonstrate how the bee brain processes complex scent mixtures by learning selected key odorants, and that the ‘selection’ of key odorants likely occurs via inhibitory neural mechanisms in the antennal lobes. We will then present evidence that olfactory memories trigger molecular changes in the sensory periphery, modifying the expression of olfactory receptor proteins. Finally, we will examine gene expression changes occurring in the memory centres of the bee brain after olfactory learning, and provide first evidence that micro-RNAs might be the regulatory mechanism underlying this molecular plasticity.
30 August l Dr Dick Zimmer l University of California
Keystone Species and Molecules of Keystone Significance
The keystone species concept provides a valuable framework for integrating findings across boundaries between traditional disciplines that scale from cellular mechanisms of chemical defense to behavioural traits and community function. Select bioactive compounds are rare within native habitats, but their impacts can be disproportionately large and connect such seemingly disparate processes as microbial loop dynamics and apex predation. Here, a general theory is developed and mechanisms are proposed that could lead to the evolution of molecules of keystone significance. Through convergent evolution, these compounds inform phylogenetically diverse organisms, initiate major trophic cascades, and structure respective communities within terrestrial, freshwater, coastal-ocean and open-ocean habitats.
23 August l Prof David Evans l Diamantina Institute, The University of Queensland
Genome-wide association studies and extensions of this methodology in the Avon Longitudinal Study of Parents and Children
The Avon Longitudinal Study of Parents and Children (ALSPAC) is a large population based cohort of 10,000 mothers and their children from the south-west of England. Since its inception in 1992, the study has contributed to hundreds of epidemiological investigations and most recently over thirty genome-wide association studies of complex traits and diseases in human populations. This talk will showcase the results of some of the most recent genome-wide association studies from the cohort and describe two new statistical methods designed to identify biological intermediates important in disease pathogenesis, and quantify the importance of maternal genotype on offspring phenotype respectively.
16 August l Dr Matt Robinson l Queensland Brain Institute, The University of Queensland
Estimating and partitioning genetic variance in wild populations
The underlying basis of genetic variation in quantitative traits, in terms of the number of causal variants and the size of their effects, is largely unknown in natural populations. The expectation is that complex quantitative trait variation is attributable to many, possibly interacting, causal variants, whose effects may depend upon the sex, age and the environment in which they are expressed. In this talk I will describe methods to partition genetic variation for complex traits across genomic regions within ecological study populations. I will then provide an example in a natural population, demonstrating that genetic variation in wing length in the great tit (Parus major) reflects contributions from multiple genomic regions.
Shrinking heads and rapid speciation of Indo-Australian sea snakes
Sea snakes evolved from Australia’s venomous land snakes and have diversified to produce >60 species spanning the Indo-Pacific. I will present molecular studies showing that diversification rates in sea snakes outpaced their terrestrial relatives, but the majority of marine species are accounted for by an explosively speciating clade that substantially post-dates the initial marine invasion. Comparative and population genetic analyses of this group suggest that rapid and repeated transitions in head size associated with diet are linked to accelerated speciation. Particularly remarkable are ‘microcephalic’ forms that have tiny heads and narrow fore-bodies and are specially adapted to hunt eels in burrows.
Snake venoms and antivenoms in sub-Saharan Africa: new approaches to improve antivenom therapy
Snakebite is a neglected tropical disease that kills up to 100,000 people each year. Antivenom remains the only therapy that specifically targets and neutralises the toxic components found in venom. Unfortunately, antivenom remains expensive for those people who suffer the greatest burden of envenoming – the rural poor people of the tropics. In addition, many antivenom products have a low dose efficacy, cause side effects and are ineffective against the toxins that cause local tissue damage. This talk will discuss new methodological and collaborative approaches to improve antivenom therapy and its delivery to the rural poor people of Africa.
Sexual selection theory: was everything already said in the 1970s?
Two key papers appeared in the 1970s: Rob Trivers published a hugely influential chapter outlining the reasons why there are often sex differences in care, and later Emlen & Oring produced the concept of the operational sex ratio, explaining why one sex has to compete more strongly for matings than the other. I will review progress in the fields that these papers helped to shape, and ask what insights are still valid today, and what aspects have become modified in current textbooks (and why).
Can genomics save the Tasmanian devil from extinction?
The Tasmanian devil, Australia's largest remaining marsupial carnivore, faces extinction in the wild due to the emergence of a new infectious disease. Devil Facial Tumour Disease (DFTD) is a contagious cancer that is spread as an allograft during biting. Devils have low genetic diversity at the Major Histocompatibility Complex (MHC). We originally proposed that devils were essentially immunological clones, and that cancer cells were able to pass between unrelated animals without triggering an immune response due to this lack of MHC diversity. The discovery of MHC-disparate animals in northwestern Tasmania raised hopes that some of these animals may be able to mount an immune response against DFTD. Indeed, the frequency of disease in these populations remains low. However, we have recently shown that the tumour is able to evade the immune response in MHC disparate animals through the down regulation of cell surface MHC. I will discuss the use of genomics and transcriptomics to help us to understand the disease, its evolutionary trajectory and the role of genomics in the quest to save the species from extinction in the wild and in Australia's largest captive insurance program.
Selection, quantitative genetics, and effects of climate change in a wild mammal
Evolutionary dynamics are determined by patterns of selection and genetic variance; an understanding of natural selection therefore also requires analysis of the genetic basis of the multivariate phenotypes on which selection acts. I present here data from a long-term study of a wild red deer population. Multivariate analyses of sexually-selected male weaponry and female life history traits indicate evolutionary genetic constraints that are not apparent at either a phenotypic or a univariate level. Natural populations are also dependent on their environment, and the deer population is experiencing complex effects of climate change acting via multiple pathways. My general aim is to illustrate the insights that long-term studies of wild populations can give into evolutionary and ecological processes.
The community ecology of disease: viral pathogens in Pacific coast grasslands of North America
The microbial community that inhabits every free-living organism can control critical host vital rates including lifespan and reproductive output. However, the mechanisms governing the composition of natural pathogen communities have received little attention. Pathogen communities are regulated by within-host processes, such as cross-protective immunity, and by factors external to the host, such as gradients in the abiotic environment, host community, and vector community. I will describe a series of field and theoretical studies examining the role of these processes in the structure of coexisting aphid-vectored, viral pathogens (barley and cereal yellow dwarf viruses) on the Pacific Coast of North America.
Physiology, abundance and management: an integrated approach
In the early 20th century, ecology was widely considered a sub-discipline of physiology. The boundaries, if they existed, were blurred. Much of the remainder of the century saw ecology flourish to become a primary source of evidence for environmental management. Physiology’s influence, by comparison, was most pronounced in the biomedical sciences. That, largely unintentional, separation is now being overcome in several ways. Here, I’ll focus on the value of the re-integration of physiological approaches into ecological thinking. The emphasis will be on the understanding and management of abundance, which lies at the heart of much environmental policy. Many of the examples will be drawn from the Antarctic.
The Reef Aerosol Cloud Climate Feedback over the Great Barrier Reef and Western Pacific and Links to Coral Bleaching
There is now a significant amount of evidence which strongly suggests that coral reefs produce cloud nucleating aerosol substances such as dimethylsulphide (DMS) that affect low level cloud formation over reefs in the Great Barrier Reef and western Pacific, thus affecting sea surface temperatures. This talk will review this information and highlight recent studies at Heron Island that suggest that coral reefs produce “seed” aerosol particles that lead to low level cloud formation (i.e. marine stratiform cloud). The state of the tide and rainfall events over reefs produce huge pulses of atmospheric DMS over reefs when SSTs <30⁰C. When SSTs > 30⁰C emissions of DMS from coral reefs shut down due to these substances being used as antioxidants in the corals symbiosis and could exacerbate coral bleaching episodes. This research strongly suggests that a “Reef Aerosol Cloud Feedback” occurs over the Great Barrier Reef and the western Pacific which significantly affects the climate of this region
The trees and the forest: persistent fast growers govern tropical tree populations
Individual life histories in natural populations of plants and animals often vary widely. Some individuals simply perform better than others, even within the same population. Such super-performers should govern population growth, but empirical tests are scarce. I present results of a study in a hyper-rich rainforest tree community. Using data of 362 species from a forest monitoring plots in Malaysia (Pasoh), we evaluated the importance of fast-growing individuals for population growth. Positive autocorrelation was ubiquitous among our study species and persistent fast growers contributed disproportionately to population growth. I discuss the implications for demographic research, diversity studies and applied ecology.
Drosophila Brain Circuitry: Lineage Principle, Brain Neuropile Ultrastructure, Synaptic Connectivity
The Drosophila central brain is formed by a stereotyped set of approximately 100 paired lineages, each one derived from one stem cell (neuroblast). Lineages represent appropriate structural/developmental units of brain circuitry. My talk will summarize our research aimed at to reconstructing the projection of all lineages throughout development, thereby generating an accurate map of Drosophila brain circuitry at the level of neuron populations (“macro-circuitry”). Furthermore, I will talk about our analysis of circuitry at the level of individual synapses (“micro-circuitry”), which requires electron microscopy. We have developed the software required for the automated recording, registration and navigation of large EM image data sets.
Niche Conservatism, Evolution, and Applied Ecology: Challenges and Opportunities
Many applied ecological problems have significant evolutionary dimensions. Pest problems are exacerbated because pest species adapt to imposed control measures, invasive species become more problematic as they adapt to new habitats, and emerging diseases may strike once pathogens evolve to use novel hosts. By contrast, conservation problems may exist because of the absence of sufficient adaptive responses to novel environments by species heading toward extinction. I will argue that all these issues involve abstractly the same problem – understanding niche conservatism, vs. evolution. An emerging theoretical framework provides insight into why some species exhibit niche conservatism, whereas others show rapid niche evolution. This framework cuts across a number of disciplines, ranging from genetics, to demography, to landscape ecology, to community ecology. The talk will distill basic messages about niche conservatism and evolution that arise from study of a wide range of theoretical models.
1 March l A/Prof Elizabeth Borer l University of Minnesota
The Nutrient Network: Grassroots science to address global-scale environmental change
Among the greatest current challenges for ecology is developing a predictive understanding of links between biodiversity and ecosystem function, on one hand, and global-scale perturbations to nutrient cycles and species distributions, on the other. While these grand challenges are global in scale, ecological experiments and sampling are done at local scales. Distributed networks are one tool with the potential to bridge the gap between site-scale experiments and global-scale predictions. The Nutrient Network is a distributed experiment addressing general ecological questions in the world’s grasslands. I will discuss my group’s experience with conceiving and implementing a distributed network of identically-replicated grassland experiments and will present some of our most recent findings.