Symposium announcement and call for presentations

Symposium announcement and call for presentations     

Intraspecific diversity loss in a predator species alters prey community structure and ecosystem functions

Loss in intraspecific diversity can alter ecosystem functions, but the underlying mechanisms are still elusive, and intraspecific biodiversity–ecosystem function (iBEF) relationships have been restrained to primary producers. Here, we manipulated genetic and functional richness of a fish consumer (Phoxinus phoxinus) to test whether iBEF relationships exist in consumer species and whether they are more likely sustained by genetic or functional richness. We found that both genotypic and functional richness affected ecosystem functioning, either independently or interactively. Loss in genotypic richness reduced benthic invertebrate diversity consistently across functional richness treatments, whereas it reduced zooplankton diversity only when functional richness was high. Finally, losses in genotypic and functional richness altered functions (decomposition) through trophic cascades. We concluded that iBEF relationships lead to substantial top-down effects on entire food chains. The loss of genotypic richness impacted ecological properties as much as the loss of functional richness, probably because it sustains “cryptic” functional diversity.

Global change is expected to generate a loss of intraspecific diversity worldwide. This mesocosm study explores whether loss of genetic and functional diversity in a predator species affects community and ecosystem functioning of lower trophic levels in pond ecosystems, revealing that diversity loss in a single consumer species can impact an entire ecosystem, reducing its functionality.     

Photocurrent genration by thylakoid membranes immobilized in an albumin-glutaraldehyde cross-linked matrix

Summary Thylakoid membranes immobilized in an albumin-glutaraldehyde cross-linked matrix were used for photocurrent generation by a photoelectrochemical cell in potentiostatic mode. This type of preparation was quite suited for such application because it retains a substantial volume of electrolyte within the porous network formed. This property allowed for introducing electron transfer inhibitors and artificial electron acceptors and further it permitted proper migration of electroactive species from the thylakoid membranes to the working electrode as required for efficient photocurrent generation.     

Mobilization of Selenite by Ralstonia metallidurans CH34

Ralstonia metallidurans CH34 (formerly Alcaligenes eutrophus CH34) is a soil bacterium characteristic of metal-contaminated biotopes, as it is able to grow in the presence of a variety of heavy metals. R. metallidurans CH34 is reported now to resist up to 6 mM selenite and to reduce selenite to elemental red selenium as shown by extended X-ray absorption fine-structure analysis. Growth kinetics analysis suggests an adaptation of the cells to the selenite stress during the lag-phase period. Depending on the culture conditions, the medium can be completely depleted of selenite. Selenium accumulates essentially in the cytoplasm as judged from electron microscopy and energy-dispersive X-ray analysis. Elemental selenium, highly insoluble, represents a nontoxic storage form for the bacterium. The ability of R. metallidurans CH34 to reduce large amounts of selenite may be of interest for bioremediation processes targeting selenite-polluted sites.     

Synopsis of the genus Mitriostigma (Rubiaceae) with a new monocaulous species from south Cameroon

Mitriostigma monocaule Sonké & Dessein sp. nov., a new Rubiaceae species from south Cameroon is described and illustrated. The novelty is easily separated from the other four Mitriostigma species by its monocaulous growth form, the other species being shrubs, sub-shrubs, or occasionally trees. Another typical character for the species is its supra-axillary inflorescences paired at the nodes. The novelty is related to M. barteri , from which it further differs in the somewhat larger leaves with a more pronounced acumen and a higher number of secondary veins. A first conservation status for the species is given. A synopsis of the genus Mitriostigma with a taxonomic key is also provided.