Ecology of bathyal polychaete fauna at an Arctic-Atlantic boundary (Faroe-Shetland Channel, North-east Atlantic)

By reference to a series of 15 sampling stations spanning the West Shetland Slope (150-1000 m; Faroe-Shetland Channel, North-east Atlantic) we examined the potential environmental controls on the standing stock, diversity and composition of the polychaete fauna. In contrast to the majority of studied bathyal environments, the Faroe-Shetland Channel has a highly complex and dynamic hydrographic regime, particularly notable for extreme thermal variability at mid-slope depths (i.e. 7°C range at ca. 500 m). Contrary to general expectation, polychaete biomass increased (rather than decreased) with depth. Species diversity exhibited a parabolic pattern with depth, maximum diversity occurring at depths of 350-550 m, rather shallower than observed in other bathyal studies, and possibly linked with a maximum in habitat temperature range. Multivariate analyses of faunal composition suggested a separation of the sampling stations into a shallower and a deeper group, with temperature exerting a major control on polychaete species distributions. The decline in diversity below 600 m (i.e. the descending limb of the parabolic relationship) may be a result of historically limited immigration/recolonization of the thermally isolated Arctic deep-water basins that feed the cold-water flow through the Faroe-Shetland Channel. The bathymetric distribution of polychaetes and other benthos in this region appears to be intimately linked with the thermal regime, having a long-term impact (geological timescales) on the deep-water species pool and leading to local enhancement of diversity where cold- and warm-water masses meet and mix.     

Mapping and Genetic Characterization of Loci Controlling the Restoration of Male Fertility in Ogura CMS Radish

Three Raphanus populations (BC1, F2 and R8) each segregating for the restoration of Ogura CMS were used tomap restorer loci. The three restorer loci, Rf1, Rf2 and Rf3, each exhibited dominant restoring alleles and wereeach mutually epistatic. Rf1 was mapped to the upper region of Rs1 using data from each population. Rf2 wasmapped to the middle of Rs2 using both the F2 and R8 populations. Rf3 was mapped to the upper region of Rs7using the R8 population. The marker analysis and linkage mapping of the BC1 and F2 populations were describedpreviously (Bett and Lydiate, 2003). Scoring at 114 marker loci in R8 population allowed a new map ofthe Raphanus genome to be integrated with the consensus map. The complex genetic control of the restoration ofOgura CMS in Raphanus is compared with the more simple genetic control of this trait previously described inB. napus. Markers linked to each of the three restorer loci will allow the routine generation and verification ofdefined restorer and maintainer lines for various combinations of defined restorer loci. Although the restorationof Ogura CMS in Raphanus probably involves additional loci, the identification of three loci and diagnosticmarkers for each provides a solid foundation for the development of a holistic model for the genetic control ofthis trait through mapping in additional populations.     

Definition of breeding objectives and optimum crossbreeding levels for goats in the smallholder production systems

The objective of this study was to define breeding objectives and consequently determine optimum crossbreeding levels for goats in the smallholder production systems. Profits and economic values (EVs) were estimated for four genotypes namely (a) original stock or local goat breeds with 0% German Alpine blood level (OS), (b) F1 with 50% German Alpine blood level (F1), (c) first backcross with 75% German Alpine blood level (B1) and (d) second backcross with 87.5% German Alpine blood level (B2). The EVs were estimated for average daily milk yield (DMY, kg), average post-weaning daily gain (ADG, kg), number of kids weaned (NKW), mature weight (MW, kg) and 12-month live weight (LW, kg). Profitability in Kenyan Shilling (KES) without risk was optimal (KES 6038.02) for the B1 genotype. Economic values without risk for most traits were highest for the F1 genotype, i.e., KES 64.85 (ADG), 24.02 (NKW), −27.55 (MW) and 84.51 (LW). There was, however, a 23% reduction in profits in the F1 genotype. It was evident that crossbreeding would improve the profitability of the smallholder farms, but not beyond the 75% grade level. A similar trend was observed when risk was incorporated. Differences in profitability with and without risk were less than 0.005% for all the genotypes. However, differences in EVs were large, ranging from −28% to +19%; DMY had the largest differences. Therefore, incorporation of risk in estimation of EVs for traits of importance is necessary. This study has also demonstrated that crossbreeding to a higher grade level is not necessarily compensated for by a high performance in most traits. Therefore, a crossbreeding program targeting B1 (75%) crossbreds would be desirable for implementation in the smallholder production systems.