Abstract: Wandering albatrosses have been subjected to numerous taxonomic revisions due to discoveries of new species, analyses of morphological data and, more recently, the inclusion of genetic data. The small population of albatrosses (170 individuals including 26 pairs breeding annually) on Amsterdam Island in the Indian Ocean, Diomedea amsterdamensis, has been given species status based on plumage and morphometrics, but genetic data published to date provide weak support and its specific status remains controversial for some authors. We used mitochondrial control region sequence data to elucidate the relationship of the Amsterdam albatross within the wandering albatross complex (Diomedea amsterdamensis, D. antipodensis, D. dabbenena and D. exulans). Three novel haplotypes were present in 35 individuals from Amsterdam Island, and were highly divergent (3.67.3%) from haplotypes found in the other three members of the wandering albatross complex. Low levels of genetic variation in Amsterdam albatross likely resulted, at least in part, from a population bottleneck. Geographic isolation in the wandering albatross complex is maintained by high natal philopatry. As Amsterdam Island is the only breeding ground for this critically endangered species, we strongly urge conservation efforts in the area, especially in relation to long line fisheries and other threats such as disease and introduced predators, and it be listed as a distinct species.

Abstract: W6. FSA 99-51

Abstract: Volcanic passive margins (VPMs) are characterized by large volumes of melt emplaced within the lithosphere during break-up processes. Several data and a recently proposed conceptual model of volcanic margin development suggest that VPMs are fed from localized crustal zones of magma storage, underlying large polygenetic volcanoes localized above diapir-like instabilities of the asthenosphere. We investigated the magma flow pattern within the coast-parallel dyke swarm of the East Greenland VPM, which is the only outcropping VPM, over a distance of 125 km. The 44 sampled dykes are representative of the successive families of intrusions. Igneous petrofabrics are constrained by the measurements of the anisotropy of magnetic susceptibility. The magnetic fabrics are of medium to low anisotropy (P' < 1.08) and show moderately oblate ellipsoids (T > 0) . Flow-related fabrics are recorded in 75 per cent of the sampled dykes. We infer the flow directions from the imbrication geometry of the magnetic foliation planes at the dyke margins, and check the results by measuring the preferred orientation of plagioclase in thin sections cut in the magnetic principal planes. Due to probable fabric superposition, the magnetic lineation represents the zone axis for the distribution of magnetic foliation plane. We obtained 23 reliable flow directions that are predominantly horizontal and directed away from identified crustal reservoirs. This flow pattern supports the proposed model of VPM growth, and emphasizes the localized nature of the magma sources in the mantle. The entire flood basalt sequence appears to have been fed by a restricted number of crustal reservoirs and associated dyke swarms.