Unravelling Darwin's entangled bank: architecture and robustness of mutualistic networks with multiple interaction types

Trying to unravel Darwin's entangled bank further, we describe the architecture of a network involving multiple forms of mutualism (pollination by animals, seed dispersal by birds and plant protection by ants) and evaluate whether this multi-network shows evidence of a structure that promotes robustness. We found that species differed strongly in their contributions to the organization of the multi-interaction network, and that only a few species contributed to the structuring of these patterns. Moreover, we observed that the multi-interaction networks did not enhance community robustness compared with each of the three independent mutualistic networks when analysed across a range of simulated scenarios of species extinction. By simulating the removal of highly interacting species, we observed that, overall, these species enhance network nestedness and robustness, but decrease modularity. We discuss how the organization of interlinked mutualistic networks may be essential for the maintenance of ecological communities, and therefore the long-term ecological and evolutionary dynamics of interactive, species-rich communities. We suggest that conserving these keystone mutualists and their interactions is crucial to the persistence of species-rich mutualistic assemblages, mainly because they support other species and shape the network organization.

Adapting the Iawa List of Microscopic Features for Hardwood Identification to Delta

The IAWA List of Microscopic Features for Hardwood Identification was adapted to DELTA (DEscription Language for TAxonomy), a package of computer programs for generating taxonomic descriptions and interactive species identification. The quality of our natural language descriptions generated by DELTA are suitable to prepare a first-draft manuscript. In specific taxon descriptions, minor changes to wording and syntax are more easily accomplished with a word processor, but all taxon changes to format, syntax, and wording are best accomplished with DELTA. As the user becomes more familiar with DELTA, the descriptions become more refined and fewer changes are necessary. The highly sophisticated interactive identification (INTKEY) program is flexible and versatile with many options to meet the needs of wood anatomists engaged in wood identification.

Problems with residual and additive elements and their control through specifications

Circumstances responsible for a specification approach to the control of residual elements are reviewed. For deleterious elements, response varies from insistence on 100 % use of virgin materials to setting maximum limits on a large number of residual elements, to specifying the relative quantities of two or more interactive species. For beneficial elements, minima must be set and testing techniques must assure that the desired element is present not only in the proper amount but also in a state and location where its meliorating effects can be realized. Examples from both the alloy and ceramic fields are discussed.