Historical Ecology on Sandoy, Faroe Islands: Palaeoenvironmental and Archaeological Perspectives

We present palaeoenvironmental, geomorphological, archaeological, and place-name data which allow a holistic assessment of the history of landscape change on Sandoy, Faroe Islands, especially in terms of the changes that occurred in response to the colonization of the island by humans. In contrast to other situations in the North Atlantic region, there is considerable continuity in the patterns and processes of landscape evolution across the initial settlement horizon. Many of the characteristic features of post-settlement North Atlantic landscapes—absence of trees, widespread blanket mires, high rates of soil erosion—were already in place when the first people arrived. Although human impact on Sandoy appears to have been light, conversely, the unusual environment forced major alterations of the subsistence economy imported by the colonists. Settlement-era archaeological records suggest that, from the start, patterns of resource use differed substantially from the regional norm, and these differences became amplified over time as the Faroese economy created a locally sustainable cultural landscape.     

Phylogenetic relationships in the subgenus Mus (genus Mus, family Muridae, subfamily Murinae): examining gene trees and species trees

Over eight kilobases (kb) of sequence from eight genes including two mitochondrial loci, Cyt b and 12S, and six nuclear loci, B2m , Zp3 , Tcp1, Sry, Smcx and Smcy , were used to investigate phylogenetic relationships among 11 taxa representing eight species within the rodent genus Mus . Particular attention was given to discerning relationships among species within the subgenus Mus including members of a Palearctic clade ( M. musculus , M. spicilegus , M. macedonicus and M. spretus ) and members of an Asian clade ( M. caroli , M. cookii and M. cervicolor ), as previous studies using different datasets have produced different topologies for taxa within these two groups. While parsimony analyses of the combined eight-gene dataset yielded a single, fully resolved tree, support values were lower for nodes resolving relationships within the Palearctic and Asian clades than they were elsewhere in the tree. In addition, a maximum likelihood analysis of the same eight-gene dataset yielded different topologies for both the Palearctic and the Asian clades. Both observations are indicative of clade instability. The nature of this instability was explored through a comparison with our previous study in which we included the two mitochondrial loci and only four of the six nuclear genes, and through an analysis of partitioned data, specifically mitochondrial vs. nuclear genes. This study underscores the importance of considering among-site rate variation in phylogeny reconstruction. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 84 , 653–662.     

Vertical Distribution of Bacterivorous Nematodes under Different Land Uses

The vertical distribution of dominant genera of bacterivorous nematodes to 150-cm depth in an aquic brown soil was compared after 14 years of four contrasting land uses, i.e., cropland-rice (CR), cropland-maize (CM), abandoned cropland (AC), and woodland (WL). The study was conducted at the Shenyang Experimental Station of Ecology, a Chinese Ecosystem Research Network (CERN) site in Northeast China. Data were analyzed using two-way analysis of variance with land use and depth as independent variables. More than 70% of Chiloplacus, Eucephalobus, and Monhystera spp. were present in the uppermost soil layer (0 to 5 cm) in the CR treatment. In contrast, Chiloplacus and Prismatolaimus spp. were distributed down to 100-cm depth in the AC and CM treatments, respectively. Differences in numbers of Acrobeles, Acrobeloides, Cephalobus, Chiloplacus, Eucephalobus, Monhystera, Plectus, and Prismatolaimus were found among land uses and at various depths. Soil C and N were correlated positively with numbers of Monhystera and Plectus in the CR treatment, Acrobeloides in the CM treatment, and Acrobeles and Acrobeloides in the AC treatment. Soil pH was correlated negatively with Monhystera, Plectus (CR), and Acrobeloides (CM, AC). The relationship of pH with Acrobeles depended on land use: positive in the WL treatment and negative in the AC treatment. Our results suggested that Cephalobus and Prismatolaimus in the CR treatment, and Chiloplacus and Prismatolaimus in the WL treatment, were insensitive to soil properties measured. Differences in vertical distribution should be considered when studying dominant bacterivorous nematode genera among land uses.     

Histological Observations of Rotylenchulus reniformis on Gossypium longicalyx and Interspecific Cotton Hybrids

Observations on the development of reniform nematode (Rotylenchulus reniformis) on roots of Gossypium longicalyx, G. hirsutum, and two interspecific hybrids derived from them were made by light microscopy. Gossypium longicalyx is reported to be immune to reniform nematode, but the mechanism(s) for resistance are unknown. Penetration of G. longicalyx roots by female nematodes was confirmed, and incipient swelling of the females, indicating initiation of maturation of the reproductive system, was observed. Female maturation occurred up to the formation of a single embryo inside the female body but not beyond this point. In both hybrids, development was inhibited but progressed further than in the immune parent. Reactions ranged from highly compatible, with the formation of active syncytia and full development of females, to incompatible with little or no development of the female. Compatible plants showed characteristic hypertrophied cells, enlarged nuclei, dense cytoplasm, and partial dissolution of cell walls, whereas incompatible plant reactions included lignification of the cells adjacent to the nematode head, or the complete collapse and necrosis of the cells involved. The need to characterize reactions and to carefully select among the plants descended from the hybrids during the introgression process, as well as the importance of combining the results of reproduction tests with histological observation of the plant-nematode interactions, is discussed.     

Juvenile Sparus aurata L. on the south coast of Ireland

Records of gilthead sea bream Sparus aurata L. in Irish and British waters since 1967 are provided together with the first observations on the ecology of 0 year group gilthead sea bream in these islands.