Natural gold particles in Eucalyptus leaves and their relevance to exploration for buried gold deposits

Eucalyptus trees may translocate Au from mineral deposits and support the use of vegetation (biogeochemical) sampling in mineral exploration, particularly where thick sediments dominate. However, biogeochemistry has not been routinely adopted partly because biotic mechanisms of Au migration are poorly understood. For example, although Au has been previously measured in plant samples, there has been doubt as to whether it was truly absorbed rather than merely adsorbed on the plant surface as aeolian contamination. Here we show the first evidence of particulate Au within natural specimens of living biological tissue (not from laboratory experimentation). This observation conclusively demonstrates active biogeochemical adsorption of Au and provides insight into its behaviour in natural samples. The confirmation of biogeochemical adsorption of Au, and of a link with abiotic processes, promotes confidence in an emerging technique that may lead to future exploration success and maintain continuity of supply

Dos and don'ts of testing the geographic mosaic theory of coevolution

The geographic mosaic theory of coevolution is stimulating much new research on interspecific interactions. We provide a guide to the fundamental components of the theory, its processes and main predictions. Our primary objectives are to clarify misconceptions regarding the geographic mosaic theory of coevolution and to describe how empiricists can test the theory rigorously. In particular, we explain why confirming the three main predicted empirical patterns (spatial variation in traits mediating interactions among species, trait mismatching among interacting species and few species-level coevolved traits) does not provide unequivocal support for the theory. We suggest that strong empirical tests of the geographic mosaic theory of coevolution should focus on its underlying processes: coevolutionary hot and cold spots, selection mosaics and trait remixing. We describe these processes and discuss potential ways each can be tested

Androgenesis:A review through the study of the selfish shellfish Corbicula spp.

info:eu-repo/semantics/publishe