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Favourable Environmental Conditions (favourable + environmental_condition)
Selected AbstractsIntroduced plants of the invasive Solidago gigantea (Asteraceae) are larger and grow denser than conspecifics in the native rangeDIVERSITY AND DISTRIBUTIONS, Issue 1 2004Gabi Jakobs ABSTRACT Introduced plant species that became successful invaders appear often more vigorous and taller than their conspecifics in the native range. Reasons postulated to explain this better performance in the introduced range include more favourable environmental conditions and release from natural enemies and pathogens. According to the Evolution of Increased Competitive Ability hypothesis (EICA hypothesis) there is a trade-off between investment into defence against herbivores and pathogens, and investment into a stronger competitive ability. In this study, we conducted field surveys to investigate whether populations of the invasive perennial Solidago gigantea Ait (Asteraceae) differ with respect to growth and size in the native and introduced range, respectively. We assessed size and morphological variation of 46 populations in the native North American range and 45 populations in the introduced European range. Despite considerable variation between populations within continents, there were pronounced differences between continents. The average population size, density and total plant biomass were larger in European than in American populations. Climatic differences and latitude explained only a small proportion of the total variation between the two continents. The results show that introduced plants can be very distinct in their growth form and size from conspecifics in the native range. The apparently better performance of this invasive species in Europe may be the result of changed selection pressures, as implied by the EICA hypothesis. [source] Life-history, genotypic, and environmental correlates of clutch size in the Glanville fritillary butterflyECOLOGICAL ENTOMOLOGY, Issue 2 2007MARJO SAASTAMOINEN Abstract 1.,Glanville fritillary butterfly (Melitaea cinxia) females lay up to 10 clutches of 50,300 eggs in their lifetime. Clutch size is an important life-history trait as larval group size affects survival throughout larval development. 2.,Two experiments were carried out in a large population cage in the field to investigate the life-history and environmental correlates of clutch size. 3.,Clutch size decreased with the cumulative number of eggs laid previously, increased with both female body weight and the number of days between consecutive clutches. 4.,Genotypic differences among females in the glycolytic enzyme phosphoglucose isomerase had a significant influence on clutch size, partly because females of particular genotypes were able to initiate oviposition earlier in the day and thereby take advantage of the most favourable environmental conditions for oviposition. 5.,Factors influencing clutch size were partly different in two summers, indicating the modulating effect of prevailing environmental conditions on reproductive performance. [source] Timing is everything: flexible phenology and shifting selection in a colonial seabirdJOURNAL OF ANIMAL ECOLOGY, Issue 2 2009Thomas E. Reed Summary 1In order to reproduce successfully in a temporally varying environment, iteroparous animals must exhibit considerable behavioural flexibility across their lifetimes. By adjusting timing of breeding each year, parents can ensure optimal overlap between the energy intensive period of offspring production and the seasonal peak in favourable environmental conditions, thereby increasing their chances of successfully rearing young. 2Few studies investigate variation among individuals in how they respond to fluctuating conditions, or how selection acts on these individual differences, but this information is essential for understanding how populations will cope with rapid environmental change. 3We explored inter-annual trends in breeding time and individual responses to environmental variability in common guillemots Uria aalge, an important marine top predator in the highly variable California Current System. Complex, nonlinear relationships between phenology and oceanic and climate variables were found at the population level. Using a novel application of a statistical technique called random regression, we showed that individual females responded in a nonlinear fashion to environmental variability, and that reaction norm shape differed among females. 4The pattern and strength of selection varied substantially over a 34-year period, but in general, earlier laying was favoured. Females deviating significantly from the population mean laying date each year also suffered reduced breeding success, with the strength of nonlinear selection varying in relation to environmental conditions. 5We discuss our results in the wider context of an emerging literature on the evolutionary ecology of individual-level plasticity in the wild. Better understanding of how species-specific factors and local habitat features affect the timing and success of breeding will improve our ability to predict how populations will respond to climate change. [source] Sugar-beet powdery mildew (Erysiphe betae)MOLECULAR PLANT PATHOLOGY, Issue 3 2002Sally Francis Summary Erysiphe betae causes sugar-beet powdery mildew, a serious fungal foliar disease resulting in sugar yield losses of up to 30%. The fungus occurs world-wide in all regions where sugar beet is grown and it also infects other edible beet crops, e.g. beetroots (garden beets). Unlike other powdery mildews, E. betae has so far received relatively little attention from pathologists and the precise mechanisms by which it infects its host remain unclear. Sources of genetic resistance have been identified in cultivated and wild Beta germplasm and molecular markers developed linked to Pm, the only single major R gene described so far, and also to QTL. Taxonomy:,Erysiphe betae (Vañha) Weltz.,Kingdom Fungi, Subdivision Ascomycotina, Class Pyrenomycetes, Order Erysiphales, Family Erysiphaceae, Genus Erysiphe. Identification:, Superficial persistent mycelium; unbranched erect conidiophores; conidia ripen singly, are hyaline, ovoid, 30,50 µm × 15,20 µm; cleistothecia globose, dark brown/black, 80,120 µm in diameter; mostly 4,8 asci per cleistothecium, mostly 2 or 3 spores per ascus. Host range:, A monophagous parasite specific to Beta species. Disease symptoms:, Infected foliage and inflorescences bear numerous powdery, white colonies. Under favourable environmental conditions the colonies coalesce, host tissue develops chlorosis and usually senesces early. Cleistothecia develop on heavily infected leaves in late summer and are small black/dark brown globose bodies resting on the mycelial surface. Control:, Chemical control and partial genetic resistance. [source] Geographical information systems-based models for offshore floating marine fish cage aquaculture site selection in Tenerife, Canary IslandsAQUACULTURE RESEARCH, Issue 10 2005Oscar M Pérez Abstract The present study focuses on the development of a standard methodology for selection of suitable sites for offshore (exposed) marine fish-cage farming (floating cages) of seabream (Sparus aurata) and seabass (Dicentrarchus labrax) in an island environment, using Tenerife as an example. Site selection is a key factor in any aquaculture operation, affecting both success and sustainability and can solve conflicts between different activities, making a rational use of the coastal space. Site selection was achieved by using geographical information systems (GIS)-based models and related technology to support the decision-making process. The framework for spatial multicriteria decision analysis used in this study began with a recognition and definition of the decision problem. Subsequently, 31 production functions (factors and constraints) were identified, defined and subdivided into eight submodels. These were then integrated into a GIS database in the form of thematic layers and later scored for standardization. At this stage, the database was verified by field sampling to establish the quality of data used. The decision maker's preferences were incorporated into the decision model by assigning weights of relative importance to the evaluation under consideration. These, together with the thematic layers, were incorporated using multicriteria evaluation techniques and simple overlays to provide an overall assessment of possible alternatives. The integration, manipulation and presentation of the results by means of GIS-based models in this sequential and logical flow of steps proved to be very effective for helping the decision-making process of site selection. Tenerife has very favourable environmental conditions for culture of marine fish and there are no totally unsuitable sites for cage farming identified in this study. On the other hand, there are few very suitable sites (high scores) either, principally due to the heavy use of the coastline and the conflicts between different users. From the 228 km2 of available area for siting cages in the coastal regions with depth less than 50 m, the total area suitable for siting cages (scores 6,8) was 37 km2. There are only 0.51 km2 of very suitable areas (score 8) and approximately 5.37 km2 of suitable (score 7), most of these being located in the southeast of the island. These relatively small areas of suitability should be put into the context of the wider use of the coastal environment around Tenerife. [source] | ||||||||||