Amplified fragment length polymorphism genetic fingerprinting challenges the taxonomic status of the near-endemic species Chara curta Nolte ex Kutz. (Characeae)

Amplified fragment length polymorphism (AFLP) genetic fingerprinting of 14 accessions of Chara curta and Chara aspera Willd., sampled across a range of habitats and morphologies in Britain, suggests that these taxa are part of the variation within a single species complex. Two primer combinations generating 397 fragments (97% of which were polymorphic), analysed by Jaccard's similarity coefficient and principal co-ordinate analysis, did not recover groups which reflect the current taxonomy. By contrast with the genetic study, a Gower general similarity coefficient and principal co-ordinate analysis of 52 morphological characters recovered the currently recognized species groups. A Mantel test showed no significant correlation between the genetic data and the morphological data, supporting the hypothesis that phenotypic variability in Chara L. is either to some extent environmentally induced or represents developmental stages. Implications for the conservation status of C. curta in Britain are discussed. (c) 2007 The Linnean Society of London, Botanical Journal of the Linnean Society, 2007, 155, 467-476.

A relationship between aerosol transport and compound-specific d13C land plant biomarker and pollen records

We examined near-surface, late Holocene deep-sea sediments at nine sites on a north-south transect from the Congo Fan (4°S) to the Cape Basin (30°S) along the Southwest African continental margin. Contents, distribution patterns and molecular stable carbon isotope signatures of long-chain n-alkanes (C27-C33) and n-alkanols (C22-C32) are indicators of land plant vegetation of different biosynthetic types, which can be correlated with concentrations and distributions of pollen taxa in the same sediments. Calculated clusters of wind trajectories and satellite Aerosol Index imagery afford information on the source areas for the lipids and pollen on land and their transport pathways to the ocean sites. This multidisciplinary approach on an almost continental scale provides clear evidence of latitudinal differences in lipid and pollen composition paralleling the major phytogeographic zonations on the adjacent continent. Dust and smoke aerosols are mainly derived from the western and central South African hinterland dominated by deserts, semi-deserts and savannah regions rich in C4 and CAM plants. The northern sites (Congo Fan area and northern Angola Basin), which get most of their terrestrial material from the Congo Basin and the Angolan highlands, may also receive some material from the Chad region. Very little aerosol from the African continent is transported to the most southerly sites in the Cape Basin. As can be expected from the present position of the phytogeographic zones, the carbon isotopic signatures of the n-alkanes and n-alkanols both become isotopically more enriched in 13C from north to south. The results of the study suggest that this combination of pollen data and compound-specific isotope geochemical proxies can be effectively applied in the reconstruction of past continental phytogeographic developments.

Reconstructed pCO2 data from tree ring cellulose d13C during 1902-2005 at 10 sites in the Tropics and Northern Subtropics

This is the reconstructed pCO2 data from Tree ring cellulose d13C data with estimation errors for 10 sites (location given below) by a geochemical model as given in the publication by Trina Bose, Supriyo Chakraborty, Hemant Borgaonkar, Saikat Sengupta. This data was generated in Stable Isotope Laboratory, Indian Institute of Tropical Meteorology, Pune - 411008, India