Biogeography

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, February 26, 2014 - 15:15 - 15:45
Institution: 
Singapore Centre on Environmental Life Sciences Engineering
Title: 

Dissecting Structure-Function Relationships In Complex Microbial Communities Using Perturbation Transcriptomics

Abstract: 

Application of ‘omics technologies, including high-throughput nucleic acid sequencing and advanced mass spectrometry, show huge potential to increase our understanding of bioprocesses occurring in both natural and engineering microbial ecosystems. Field studies of such systems are inherently complicated, while laboratory reactor models involve extensive community modifications following inoculation and may not accurately reflect the biology of the source community. Here we develop a complementary approach to dissecting structure-function relationships of complex microbial communities, by applying experimental perturbations to freshly sourced, intact communities in a controlled fashion. In an investigation examining nitrogen transformation in wastewater treatment, we use metatranscriptomics in a time series design (n=20 samples) to study changes associated with onset of oxygenation. This stimulus switches the community between de-nitrification and nitrification phases of the nitrogen cycle, thus modeling a key aspect of wastewater process control. This model permits identification of functional genes, in both known and previously unknown taxa, and represents a readily adaptable model studying structure-function relationships in microbial communities. If time permits, I will discuss how this perturbation metatranscriptomics approach has implications for improving our ability to perform metagenome assembly.

Event Date: 
Wednesday, September 28, 2011 - 18:00 - 18:15
Institution: 
University of New South Wales
Title: 

The Effects of Environmental Temperature on Biogeographic Boundaries in SAR11 Marine Bacteria.

Abstract: 

The ubiquitous SAR11 bacterial clade is the most abundant type of organism in the world's oceans, but the reasons for its success are not fully elucidated. We provide the first global characterisation of the distribution of this marine heterotrophic bacterium, from waters spanning temperatures -2ºC to 30ºC. Our data show a stable co-occurrence of paired ecotypes within both "tropical" (>20ºC) and "polar" (<10ºC) biomes, highlighting ecological niche differentiation between the major SAR11 lineages. All ecotypes display transitions in abundance that are strongly correlated to temperature. Our data demonstrates the importance of adaptive radiation in the organism's ability to proliferate throughout the world's oceans. Based on projections of sea surface temperature in 2090 we predict a redistribution of SAR11 ecotypes within a significant proportion of the ocean realm as a result of global warming.

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