Biodiversity

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, 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, August 28, 2013 - 18:00 - 18:15
Institution: 
CSIRO Canberra
Title: 

Decomposer Microbial Communities Shift from Native Eucalyptus Diversity to Pine-type Diversity in Eucalypt Forests Fragmented by Pine Plantations

Abstract: 

 
The Wog Wog Fragmentation Experiment was started 29 years ago as a collaboration between CSIRO and NSW Forestry and is one of the longest running ecological experiments in the world.  It was designed to study the effects of Pinus radiata plantations on patches of old-growth Eucalyptus forest in terms of overall health as well as plant and insect species diversity.  Early work at the site showed that, in agreement with fragmentation ecology theory, predatory and generally rarer beetles decreased in eucalyptus fragments surrounded by the newly planted pines whereas decomposer and fungus-feeding beetle species increased.  These types of edge-dependant effects penetrated at least 100m into remnant eucalyptus forest fragments.
Recently, there have been a number of new studies on diverse aspects of forest diversity and health at the site.  This recent work has focused on understory plant diversity, long-term ground-dwelling beetle diversity and population dynamics, soil nutrient levels, soil bacterial and fungal diversity, skink and bird diversity, Eucalyptus growth and demographics, and understory light and temperature regimes.  Andrew King’s presentation will focus on the interaction between soil microbial communities, altered soil carbon and nitrogen cycles, and an unexpected increase in Eucalypt growth in response to fragmentation.

Event Date: 
Wednesday, April 24, 2013 - 18:00 - 18:15
Institution: 
University of Sydney
Title: 

Domesticating E. coli

Abstract: 

Adaptation of environmental bacteria to laboratory conditions can lead to modification of important traits, what we term domestication. Little is known about the rapidity and reproducibility of domestication changes, the uniformity of these changes within a species or how diverse these are in a single culture. We analysed phenotypic changes in nutrient-rich liquid media or on agar of four E. coli strains newly isolated through minimal steps from different sources. The laboratory-cultured populations showed changes in metabolism, morphotype, fitness and in phenotypes associated with the sigma factor RpoS. Domestication events and phenotypic diversity started to emerge within 2-3 days in replicate sub-cultures of the same ancestor. In some strains, increased amino acid usage and higher fitness under nutrient limitation resembled those in mutants with the GASP (Growth Advantage in Stationary Phase) phenotype. The domestication changes are not uniform across a species or even within a single domesticated population. However, some parallelism in adaptation within repeat cultures was observed. Differences in the laboratory environment also determine domestication effects, which differ between liquid and solid media or with extended stationary phase. Important lessons for the handling and storage of organisms can be based on these studies.

 
 
The Summer Course at the Sydney Institute for Marine Science will provide a comprehensive training for students with an interest in marine microbes and ecology. Students with a background in any one of the following areas are encouraged to apply: marine science, ecology, microbiology and biotechnology. 
 
Students will develop an integrative view of the microbes in marine ecosystems in terms of their evolution, diversity, interactions and functional roles. 
 
 

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