Behavioural and chemical mechanisms behind a Mediterranean ant–ant association

1. Interspecific competition among ants is common, and so is competitive exclusion among dominant ant species. In contrast, specific associations between non‐parasitic ant species are rare, especially in the temperate zones. As an exception, the subordinate ant Camponotus lateralis frequently co‐occurs with the dominant Crematogaster scutellaris but rarely with other dominant ants. 2. This association is one of various associations between Camponotus and Crematogaster species across the world. However, the mechanisms behind these co‐occurences are largely unknown. 3. In the present study, we therefore investigated the association of Ca. lateralis and Cr. scutellaris. We studied the spatial association of the nests, interspecific aggression, both species' cuticular hydrocarbon profiles, and their propensity to follow the other species' pheromone trails. 4. Crematogaster scutellaris usually attacked and displaced the generally submissive Ca. lateralis, but was significantly less aggressive at jointly used trails. Camponotus nests were always in close proximity to Crematogaster nests. 5. The cuticular hydrocarbons of both species consisted of alkanes with chain lengths between C21 and C35. The two species had 25 hydrocarbons in common, including mono‐, di‐, and tetramethyl alkanes. Despite this qualitative similarity, however, the quantitative hydrocarbon composition differed between the two species. 6. Camponotus lateralis followed artificial trails containing trail pheromones of Cr. scutellaris, but the latter did not follow Ca. lateralis trail pheromones. Interspecific trail‐following by Camponotus, but not vice versa, has been observed in another Camponotus–Crematogaster association and may be a more general mechanism that facilitates associations between the two ant genera.     

Test structure and evolution in the Foraminifera

For about a decade shell structures have formed the basis of the main taxonomic subdivision of the Foraminifera. Recent investigations have shown that within the monolamellar nodosariaceans no evolution with respect to wall structure has taken place since the Permian. The bilamellar aragonitic forms have remained stable at least since the Jurassic (Triassic?). The bilamellar calcitic forms have remained stable since the Jurassic (Triassic?). The wall structure of the non-lamellar porcellaneous forms has shown no change since the Carboniferous. The non-lamellar monocrystalline forms first occurred in the Upper Carboniferous and appear to have remained stable ever since. The microgranular Foraminifera, first appearing in the Cambrian, disappeared in the Triassic. Their primary structure is not known. The agglutinated forms seem to have started in the Cambrian, if not before. Evolutionary development leading to a higher degree of complexity of shell structure seems to be present (agglutinated—porcellaneous—monocrystalline—monolamellar and bilamellar), and may culminate in a more phylogeny-oriented systematic subdivision than the one we have today.     

Index of Key Words

Other Index

Index of Key Words     

Plant endemism in two forests in southern Bahia, Brazil

An important factor in determining species rarity is the geographic distribution of species. Estimates were made of the level of endemism of the flora of two sites in the southern Bahian wet forest zone. Estimates were made for endemism in the Atlantic forest biome and for the much more restricted area of southern Bahia and northern Espi´rito Santo and are derived from analyses of the distributions of the species known from each area. The species checklist for each area is based on identified specimens resulting from intensive collecting in a forest near Serra Grande (40km north of Ilhe´us) and the Una Biological Reserve (40km south of Ilhe´us). Slightly less than half of the species (45.2% at Una and 47.7% at Serra Grande) have widespread distributions and 7.4% at each site are disjunct between the coastal forests and Amazonia. In the Una Reserve, 44.1% of the species are endemic to the coastal forest and 28.1% endemic to southern Bahia and northern Espi´rito Santo. At Serra Grande, 41.6% of the species are endemic to the coastal forest and 26.5% endemic to southern Bahia and northern Espi´rito Santo.     

Guilt by Association: The Culture of Accusation and the American Anthropological Association's Investigation of Darkness in El Dorado

The American Anthropological Association's investigation of the charges in Darkness in El Dorado (Tierney 2000) found that the late James Neel and Napoleon Chagnon harmed the Yanomami in the course of their research in Venezuela and Brazil, and that Chagnon had violated the ethics code of the association. The association's inquiry contravened its own policy prohibiting ethics adjudications and was structured not by the standards of an objective investigation but by aspects of contemporary anthropology. Moralized approaches to information and postmodern rejection of objectivity mark the language and methods of the inquiry. The investigating task force did not observe reasonable standards of evidence, the targets of the investigation were not represented, and task force members were compromised by conflicts of interest. The investigation and its collateral activities reflect a culture of accusation and an anthropology uncertain of its ethical or scientific stature.     

Ecological,morphological and genetic divergence of sympatric North Atlantic killer whale populations

Ecological divergence has a central role in speciation and is therefore an important source of biodiversity. Studying the micro‐evolutionary processes of ecological diversification at its early stages provides an opportunity for investigating the causative mechanisms and ecological conditions promoting divergence. Here we use morphological traits, nitrogen stable isotope ratios and tooth wear to characterize two disparate types of North Atlantic killer whale. We find a highly specialist type, which reaches up to 8.5 m in length and a generalist type which reaches up to 6.6 m in length. There is a single fixed genetic difference in the mtDNA control region between these types, indicating integrity of groupings and a shallow divergence. Phylogenetic analysis indicates this divergence is independent of similar ecological divergences in the Pacific and Antarctic. Niche‐width in the generalist type is more strongly influenced by between‐individual variation rather than within‐individual variation in the composition of the diet. This first step to divergent specialization on different ecological resources provides a rare example of the ecological conditions at the early stages of adaptive radiation.     

Lyneborgimyia magnifica gen. et sp.n. (Diptera: Syrphidae) from Tanzania,with a phylogenetic analysis of the Eumerini using new morphological characters

Lyneborgimyia magnifica gen. et sp.n. is described and placed with Merodon Meigen and Platynochaetus Wiedemann in the Merodon genus group within the tribe Eumerini. New morphological characters and terms are introduced, and precise definitions proposed for characters applied inconsistently in the literature. The species possesses several unique autapomorphies, including an additional cross‐vein between R₄₊₅ and M₁, and a sclerotized connection between sternite 1 and the metepimeron, which are unknown otherwise within Diptera. A parsimony‐based phylogenetic analysis including 73 characters from the adult morphology provides strong support for the monophyly of the Eumerini (Eumerus Meigen, Azpeytia Walker, Lyneborgimyia, Merodon, Platynochaetus) and the Merodon genus group, whereas no support is found for the possible monophyly of the genus Eumerus. A sister‐group relationship is indicated between the Afrotropical Lyneborgimyia and the Palaearctic Platynochaetus.