Crossability analysis in subgenus Tulipa of the genus Tulipa L.

A range of almost 1400 cross combinations has been carried out between 31 species of Tulipa subgenus Tulipa. Most of the sections are well separated reproductively from each other. The designated species aggregates in section Clusianae appeared to be intersterile. Also in section Kolpakowskianae the species, as far as used, cannot be combined. Some crosses between species of section Tulipanum succeeded. The species of sections Eichleres and Tulipa (including the cultivated tulip T gesneriana) could be combined in various ways, although the highest level of seed set was achieved within either section. The crossability data support the current taxonomic division. The level of reproductive isolation between sympatric species is discussed, and the importance of crossability studies for plant breeding in Tulipa pointed out briefly.     

The production‐ecological sustainability of cassava,sugarcane and sweet sorghum cultivation for bioethanol in Mozambique

We present an approach for providing quantitative insight into the production‐ecological sustainability of biofuel feedstock production systems. The approach is based on a simple crop‐soil model and was used for assessing feedstock from current and improved production systems of cassava for bioethanol. Assessments were performed for a study area in Mozambique, a country considered promising for biomass production. Our focus is on the potential role of smallholders in the production of feedstock for biofuels. We take cassava as the crop for this purpose and compare it with feedstock production on plantations using sugarcane, sweet sorghum and cassava as benchmarks. Production‐ecological sustainability was defined by seven indicators related to resource‐use efficiency, soil quality, net energy production and greenhouse gas (GHG) emissions. Results indicate that of the assessed systems, sugarcane performed better than cassava, although it requires substantial water for irrigation. Targeted use of nutrient inputs improved sustainability of smallholder cassava. Cassava production systems on more fertile soils were more sustainable than those on less fertile soils; the latter required more external inputs for achieving the same output, affecting most indicators negatively and reducing the feasibility for smallholders. Cassava and sweet sorghum performed similarly. Cassava production requires much more labour per hectare than production of sugarcane or sweet sorghum. Production of bioethanol feedstock on cultivated lands was more sustainable and had potential for carbon sequestration, avoiding GHG emissions from clearing natural vegetation if new land is opened.     

Daily routines and predator encounters in Yellowhammers Emberiza citrinella in the field during winter

Diurnal and seasonal variation in foraging behaviour of Yellowhammers Emberiza citrinella and activity of their avian predators were studied in an unmanipulated winter field situation around Uppsala, Sweden. In December, when time available for foraging was lowest, Yellowhammers seemed to be time-stressed. In order to meet their energetic needs, they reduced the time allocated to vigilance and increased the time allocated to foraging. Yellowhammers did not systematically change the time spent foraging during the day in December, which indicates time-stress, while they decreased the time spent foraging during the day in both November and February. Predator activity was highest in the afternoon, when Yellowhammers spent the least time foraging. Yellowhammers may have adopted a routine with decreasing foraging rates over the day in November and February, when time available for foraging was longer, in order to avoid foraging during periods of high predator activity. The diurnal activity pattern of predators together with daylength and energetic needs are factors that might be important in shaping daily foraging routines in small birds.     

Effects of metals on enzyme activity in plants

Abstract. Uptake of phytotoxic amounts of metal by higher plants or algae can result in inhibition of several enzymes, and in increase in activity (= induction) of others. Two mechanisms of enzyme inhibition predominate: (1) binding of the metal to sulphydryl groups, involved in the catalytic actionor structural integrity of enzymes, and (2) deficiency of an essential metal in metalloproteins or metal-protein complexes, eventually combined with substitution of the toxic metal for the deficient element. Metal accumulation in the cellular compartment of the enzyme is a prerequisite for enzyme inhibition in vivo. The induction of some enzymes is considered to play a significant role in the stress metabolism, induced by metal phytotoxicity. Peroxidase induction is likely to be related to oxidative reactions at the biomembrane; several enzymes of the intermediary metabolism might be stimulated to compensate for metal-sensitive photosynthetic reactions. The induction of enzymes and metal-specific changes in isoperoxidase pattern can be used as diagnostic criteria to evaluate the phytotoxicity of soils, contaminated by several metals. Lines for future research on metal phytotoxicity are proposed, involving the study of inhibition and induction of enzymes at the different cell membranes (especially the plasmamembrane) in vivo.     

Phylogeography of five Polytrichum species within Europe

Using allozymes and microsatellites we have analysed the genetic structure among European populations for several Polytrichum species to infer relevant factors, such as historical events or gene flow, that have shaped their genetic structure. As we observed low levels of genetic differentiation among populations, and no decreasing levels of genetic variation with increasing latitude within most of the examined species, no genetic evidence was obtained for a step-wise recolonization of Europe from southern refugia after the latest glacial period for P. commune , P. uliginosum , P. formosum and P. piliferum . The near absence of population substructuring within these species does indicate that extensive spore dispersal is the most important factor determining the genetic structure among European Polytrichum populations. Gene flow levels have apparently been sufficient to prevent genetic differentiation among populations caused by genetic drift, and to wipe out any genetic structure caused by the postglacial recolonization process. On the other hand, increased genetic differentiation of alpine P. formosum populations suggests that mountain ranges might restrict gene flow significantly among Polytrichum populations. In contrast to most examined Polytrichum species, P. juniperinum showed high levels of genetic differentiation and a profound genetic structure. Assuming that gene flow is not more restricted in P. juniperinum , these findings suggest that this species has recolonized Europe after the latest glacial period from two different refugia, one possibly being the British Isles.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society 2003, 78, 203–213.     

Development of nine polymorphic microsatellite loci in the spined loach, Cobitis taenia, and cross-species amplification in the related species C. elongatoides, C. taurica and C. tanaitica

Nine polymorphic microsatellite loci were developed for the spined loach, Cobitis taenia (Teleostei: Cobitidae). The loci were validated using 50 individuals from a population in Belgium. Moderate to high levels of polymorphism were detected (two to 11 alleles). In addition, most markers amplified successfully in three closely related taxa that are known to hybridize with C. taenia: C. elongatoides, C. taurica and C. tanaitica. Some of the loci are most likely diagnostic among species. These markers will be valuable for the study of the historical and contemporary interactions within C. taenia and the Cobitis species complex.     

Alternative Feeding Strategies and Potential Disease Transmission in Wisconsin White-Tailed Deer

ABSTRACT We conducted experimental feeding using 3 feeding methods (pile, spread, trough) and 2 quantities (rationed, ad libitum) of shelled corn to compare deer activity and behavior with control sites and evaluate potential direct and indirect transmission of infectious disease in white-tailed deer (Odocoileus virginianus) in central Wisconsin, USA. Deer use was higher at 2 of the feeding sites than at natural feeding areas (P ≤ 0.02). Deer spent a higher proportion of time (P < 0.01) feeding at pile (49%) and spread (61%) treatments than at natural feeding areas (36%). We found higher deer use for rationed than ad libitum feeding quantities and feeding intensity was greatest at rationed piles and lowest at ad libitum spreads. We also observed closer pairwise distances (≤0.3 m) among deer when corn was provided in a trough relative to spread (P=0.03). Supplemental feeding poses risks for both direct and indirect disease transmission due to higher deer concentration and more intensive use relative to control areas. Concentrated feeding and contact among deer at feeding sites can also increase risk for disease transmission. Our results indicated that restrictions on feeding quantity would not mitigate the potential for disease transmission. None of the feeding strategies we evaluated substantially reduced the potential risk for disease transmission and banning supplemental feeding to reduce transmission is warranted.     

THE USE OF SMALL FARM DAMS IN THE TRANSKEI AND CISKEI FOR THE PRODUCTION OF TABLE-FISH USING AISCHGRUND CARP

SUMMARY

Small stockwatering dams are usually ignored in the Transkei and Ciskei in fishfarming ventures. This paper reports on experimental results in fish production studies, using Aischgrund carp, which were obtained in the Ciskei and which indicate that economically worthwhile fish production can be achieved in such dams.