The Maia detector array and x-ray fluorescence imaging system: Locating rare precious metal phases in complex samples

X-ray fluorescence images acquired using the Maia large solid-angle detector array and integrated real-time processor on the X-ray Fluorescence Microscopy (XFM) beamline at the Australian Synchrotron capture fine detail in complex natural samples with images beyond 100M pixels. Quantitative methods permit real-time display of deconvoluted element images and for the acquisition of large area XFM images and 3D datasets for fluorescence tomography and chemical state (XANES) imaging. This paper outlines the Maia system and analytical methods and describes the use of the large detector array, with a wide range of X-ray take-off angles, to provide sensitivity to the depth of features, which is used to provide an imaging depth contrast and to determine the depth of rare precious metal particles in complex geological samples. © 2013 SPIE

A metabarcoding analysis of the wrackbed microbiome indicates a phylogeographic break along the North Sea–Baltic Sea transition zone

Sandy beaches are biogeochemical hotspots that bridge marine and terrestrial ecosystems via the transfer of organic matter, such as seaweed (termed wrack). A keystone of this unique ecosystem is the microbial community, which helps to degrade wrack and re-mineralize nutrients. However, little is known about this community. Here, we characterize the wrackbed microbiome as well as the microbiome of a primary consumer, the seaweed fly Coelopa frigida, and examine how they change along one of the most studied ecological gradients in the world, the transition from the marine North Sea to the brackish Baltic Sea. We found that polysaccharide degraders dominated both microbiomes, but there were still consistent differences between wrackbed and fly samples. Furthermore, we observed a shift in both microbial communities and functionality between the North and Baltic Sea driven by changes in the frequency of different groups of known polysaccharide degraders. We hypothesize that microbes were selected for their abilities to degrade different polysaccharides corresponding to a shift in polysaccharide content in the different seaweed communities. Our results reveal the complexities of both the wrackbed microbial community, with different groups specialized to different roles, and the cascading trophic consequences of shifts in the near shore algal community

Environmental and Climatic Determinants of Molecular Diversity and Genetic Population Structure in a Coenagrionid Damselfly

Identifying environmental factors that structure intraspecific genetic diversity is of interest for both habitat preservation and biodiversity conservation. Recent advances in statistical and geographical genetics make it possible to investigate how environmental factors affect geographic organisation and population structure of molecular genetic diversity within species. Here we present a study on a common and wide ranging insect, the blue tailed damselfly Ischnuraelegans, which has been the target of many ecological and evolutionary studies. We addressed the following questions: (i) Is the population structure affected by longitudinal or latitudinal gradients?; (ii) Do geographic boundaries limit gene flow?; (iii) Does geographic distance affect connectivity and is there a signature of past bottlenecks?; (iv) Is there evidence of a recent range expansion and (vi) what is the effect of geography and climatic factors on population structure? We found low to moderate genetic sub-structuring between populations (mean FST = 0.06, Dest = 0.12), and an effect of longitude, but not latitude, on genetic diversity. No significant effects of geographic boundaries (e.g. water bodies) were found. FST-and Dest-values increased with geographic distance; however, there was no evidence for recent bottlenecks. Finally, we did not detect any molecular signatures of range expansions or an effect of geographic suitability, although local precipitation had a strong effect on genetic differentiation. The population structure of this small insect has probably been shaped by ecological factors that are correlated with longitudinal gradients, geographic distances, and local precipitation. The relatively weak global population structure and high degree of genetic variation within populations suggest that I. elegans has high dispersal ability, which is consistent with this species being an effective and early coloniser of new habitats