BACKGROUND It has been known for more than 20 years that the early aggregation of the slime mould Dictyostelium is driven by periodic waves of cAMP, which instruct the cells to collect at the aggregation centre. Although it has been hypothesized that cAMP waves are also involved in the organization of multicellular morphogenesis, wave propagation in the later stages of Dictyostelium development...

In a 1.140 km² study area of the volcanic West Eifel, a comprehensive investigation established the correlation between red wood ant mound (RWA; Formica rufa-group) sites and active tectonic faults. The current stress field with a NW-SE-trending main stress direction opens pathways for geogenic gases and potential magmas following the same orientation. At the same time, Variscan and Mesozoic fa...

Fries et al. (1999), hereafter referred to as FBW, present interesting experimental data showing that biogenic mounds, formed by the conveyor-belt feeding polychaete Cistenides (Pectinaria) gouldii, can be reshaped into asymmetric bedforms at bed shear stresses below the Shields threshold of sediment movement. The ®nal geometry of the current ripples was found to depend on the spatial density o...

The mechanisms by which even the clearest of keystone or dominant species exert community-wide effects are only partially understood in most ecosystems. This is especially true when a species or guild influences community-wide interactions via changes in the abiotic landscape. Using stable isotope analyses, we show that subterranean termites in an East African savanna strongly influence a key e...

1. The malarial parasite is extracellular throughout its entire life cycle; that is, when it is not free in the blood serum, it is attached to the external surface of the red corpuscle. 2. Adult parasites follow the same procedure in attaching themselves to the outer surface of the red corpuscles as do the young parasites. 3. Adult parasites are most frequently seen attached to surface corpuscu...

The finding that regular spatial patterns can emerge in nature from local interactions between organisms has prompted a search for the ecological importance of these patterns. Theoretical models have predicted that patterning may have positive emergent effects on fundamental ecosystem functions, such as productivity. We provide empirical support for this prediction. In dryland ecosystems, termi...

1 The effect of physical ecosystem engineering – structurally mediated modification of the abiotic environment by organisms – on species richness and composition probably depends on the area of observation and environmental context. 2 We develop specific hypotheses to evaluate how such effects will vary with spatial scale and environmental variability, and test these hypotheses by examining the...