Ecology



The Centre for Systems Genomics is holding a 1-day symposium on metagenomics and microbiome research, Tuesday November 17 at Bio21. 

Interested in presenting? Register now! and complete the abstract section.

This free event will feature talks on a range of microbiome-related topics including new computational and lab methods, covering a range of application areas including the human microbiome in health and disease, environmental metagenomics, ecology, agriculture and ancient DNA.

Event Date: 
Wednesday, September 30, 2015 - 18:00 - 18:15
Institution: 
Macquarie University
Title: 

Aquifer microbial community assembly: do neutral processes dominate?

Abstract: 

Community assembly processes can be condensed into four categories: dispersal, selection, drift and speciation. We tested aquifer communities (of Archaea, Bacteria, Fungi, and Eukarya generally) for evidence that dispersal limitation and environmental selection play a role in determining community biodiversity and composition. We found only weak evidence for these processes at a regional scale of up to 250 km and spanning several significant dispersal barriers. I discuss the possibility that neutral (i.e. non-deterministic, non-selective) processes dominate in groundwater ecosystems, and the spatial scaling of these processes.

 

Event Date: 
Wednesday, August 26, 2015 - 19:00 - 19:45
Institution: 
CSIRO
Title: 

The evolution of mutualistic trait variation in rhizobial symbionts across genetic and geographic scales

Abstract: 

Interactions between plants and nitrogen-fixing rhizobial bacteria are characterized by high genetic diversity for traits important to the outcome of the interaction at the population and species level. However, the selective processes underpinning the generation and maintenance of genetic and phenotypic variation in such interactions are not well understood. I will present an overview of data gathered from a series of experiments using interactions between Acacia spp. and their associated rhizobia, and that address questions regarding the ecological and evolutionary drivers of trait variation across different scales.  Specifically, I will discuss how 1) phylogenetic constraint; 2) within-species local adaptation; 3) nutrient availability; and 4) partner diversity and identity, influence patterns of specialization and community structure in legume-rhizobial mutualistic interactions. Our results suggest that both host-bacterial and bacterial-bacterial interactions are important for understanding evolutionary and ecological dynamics and highlight the importance of designing experiments that span different genetic and geographic scales.

Event Date: 
Wednesday, May 27, 2015 - 18:15 - 18:30
Institution: 
University of Western Sydney & Macquarie University
Title: 

Structure, diel functional cycling and viral ecological filtering in the microbiome of a pristine coral atoll in the Indian Ocean

Abstract: 

Given the role of microbes as both indicators and drivers of ecosystem health, establishing baselines in pristine environments is crucial to predicting the response of marine habitats to environmental change.  Here we describe a survey of microbial community composition and metatranscriptomic gene expression across the Indian Ocean, encompassing the first samples from the pristine Salomon Atoll in the Chagos Archipeligo.  We observed strong patterns in beta-diversty  which reflected  Longhurst biogeographical  provinces established  using primary productivity and thermohaline properties of ocean currents.  Samples from within Salomon Atoll showed a highly unique community which was remarkably different even from adjacent samples despite constant water exchange.  This pattern was driven by the dominance of the photosynthetic cyanobacterium Synechococcus within the lagoon, the diel activity of which was responsible for driving shifts in the transcriptional profile of samples.  Inside the lagoon, increases in the expression of genes related to photosynthesis and nutrient cycling associated with the bottom-up control of bacterial populations, however the expression of viral proteins increased five-fold within the lagoon during the day, indicating a concomitant top-down control of bacterial dynamics byphage.  Indeed, genome recruitment against Synechococcus reference genomes suggested  viruses  provide  an  ecological filter for determining the diversity patterns in this system. This study also represented a proof of concept for  using a ‘citizen oceanography’ approach utilzing tools that may easily be adapted to deployment on any ocean going yacht, greatly expanding the scale and outreach of marine microbiology studies. 
 

Event Date: 
Wednesday, November 27, 2013 - 19:00 - 20:00
Institution: 
Deptartment of Civil and Environmental Engineering, MIT
Title: 

The Ocean....from the microscale

Abstract: 

At a time when microbial ecology is largely traveling along genomic roads, we cannot forget that the functions and services of microbes depend greatly on their behaviors, encounters, and interactions with their environment. New technologies, including microfluidics, high-speed video-microscopy and image analysis, provide a powerful opportunity to spy on the lives of microbes, directly observing their behaviors at the spatiotemporal resolution most relevant to their ecology. I will illustrate this 'natural history approach to microbial ecology' by focusing on marine bacteria, unveiling striking adaptations in their motility and chemotaxis and describing how these are connected to their incredibly dynamic, gradient-rich microenvironments. Specifically, I will present (i) direct evidence for a diverse gallery of microscale microbial hotspots in the ocean; (ii) a new framework for understanding the evolution of microbial diversity in the ocean; and (iii) microfluidic experiments to capture the dramatic chemotactic abilities of bacterial pathogens towards the roiling surface of coral hosts. Through these examples, I hope to show that direct visualization can foster a new layer of understanding in microbial ecology and can help us unlock the ocean's microscale.

Event Date: 
Wednesday, July 31, 2013 - 18:15 - 18:30
Institution: 
University of Technology Sydney
Title: 

The Sydney Harbour microbiome: bacterioplankton diversity and dynamics

Abstract: 

Sydney Harbour and its surrounding coast is an iconic habitat that supports a diverse ecosystem however the composition and dynamics of bacterioplankton in the system remain a major knowledge gap. The harbour and coast also provide a model system for investigating the spatiotemporal distribution of microorganisms across multiple physicochemical gradients and their response to anthropogenic input. Using next-generation DNA sequencing, we provide a comprehensive profile of microbial communities from a range of habitats inside the harbour and show strong biogeographic patterns in taxonomic composition.  Using network analysis to visualize correlations between community structure and environmental variables we have identified the key drivers of community partitioning. Combined these results lead to a more detailed understanding of the diversity and roles of bacterioplankton in Sydney Harbour and its surrounds, and provide insight into marine microbial ecology generally. 

Reference: JOB351
Employer: Hawkesbury Institute for the Environment
Application deadline: CLOSED
Event Date: 
Wednesday, March 27, 2013 - 18:15 - 18:30
Institution: 
Hawkesbury Institute for the Environment, University of Western Sydney
Title: 

Effect of Huanglongbing on the structure and functional diversity of microbial communities associated with citrus.

Abstract: 

Plant-microbe interactions lie at the heart of plant performance and ecology. It has been postulated that disruption of multi-trophic interactions in a stable ecosystem under the influence of invading phytopathogens will cause community reorganization and changes in the local feedback interactions. However, there is a paucity of knowledge on the extent to which such community shifts may occur, on the dynamics of changes and on the putative effects regarding the functioning of ecosystems. We have used Citrus-‘Candidatus Liberibacter asiaticus’ [Las, causal agent of devastating Huanglongbing (HLB) disease] as a host pathogen model to characterize the structure, function and interactions of plant-associated microbial communities. We applied a suit of metagenomic techniques to provide detailed census of citrus associated microbiomes. Our results confirmed that Las is the sole causal agent of HLB in Florida and revealed that HLB significantly re-structures the composition of native microbial community present either in leaf, roots and rhizosphere of citrus. Functional microarray (Geochip) and shotgun metagenomic sequencing showed that HLB has severe effects on various functional guilds of bacteria involved in key ecological processes including nitrogen cycling and carbon fixation. Overall, the metagenomic studies provided evidence that change in plant physiology mediated by Las infection could elicit shifts in the composition and functional potential of plant associated microbial communities. In the long term, these fluctuations might have important implications for the productivity and sustainability of citrus producing agro-ecosystems.

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