Search results for "Fora"
showing 10 items of 1086 documents
Forage silica and water content control dental surface texture in guinea pigs and provide implications for dietary reconstruction.
2019
Significance Ingesta leave characteristic wear features on the tooth surface, which enable us to reconstruct the diet of extant and fossil vertebrates. However, whether dental wear is caused by internal (phytoliths) or external (mineral dust) silicate abrasives is controversially debated in paleoanthropology and biology. To assess this, we fed guinea pigs plant forages of increasing silica content (lucerne < grass < bamboo) without any external abrasives, both in fresh and dried state. Abrasiveness and enamel surface wear increased with higher forage phytolith content. Additionally, water loss altered plant material properties. Dental wear of fresh grass feeding was similar to lucerne brows…
Effects of predation pressure and resource use on morphological divergence in omnivorous prey fish
2013
Background. Body shape is one of the most variable traits of organisms and responds to a broad array of local selective forces. In freshwater fish, divergent body shapes within single species have been repeatedly observed along the littoral-pelagic axes of lakes, where the structural complexity of near shore habitats provides a more diverse set of resources compared to the open-water zones. It remains poorly understood whether similar resource-driven polymorphism occurs among lakes that vary in structural complexity and predation pressure, and whether this variation is heritable. Here, we analyzed body shape in four populations of omnivorous roach (Rutilus rutilus) inhabiting shallow lakes.…
Interactions between Climate Change and Infrastructure Projects in Changing Water Resources: An Ethnobiological Perspective from the Daasanach, Kenya
2021
The fast and widespread environmental changes that have intensified in the last decades are bringing disproportionate impacts to Indigenous Peoples and Local Communities. Changes that affect water resources are particularly relevant for subsistence-based peoples, many of whom already suffer from constraints regarding reliable access to safe water. Particularly in areas where water is scarce, climate change is expected to amplify existing stresses in water availability, which are also exacerbated by multiple socioeconomic drivers. In this paper, we look into the local perceptions of environmental change expressed by the Daasanach people of northern Kenya, where the impacts of climate change …
Merging cranial histology and 3D-computational biomechanics : A review of the feeding ecology of a Late Triassic temnospondyl amphibian
2021
Finite Element Analysis (FEA) is a useful method for understanding form and function. However, modelling of fossil taxa invariably involves assumptions as a result of preservation-induced loss of information in the fossil record. To test the validity of predictions from FEA, given such assumptions, these results could be compared to independent lines of evidence for cranial mechanics. In the present study a new concept of using bone microstructure to predict stress distribution in the skull during feeding is put forward and a correlation between bone microstructure and results of computational biomechanics (FEA) is carried out. The bony framework is a product of biological optimisation; bon…
Arbuscular mycorrhizal fungi altered the hypericin, pseudohypericin, and hyperforin content in flowers of Hypericum perforatum grown under contrastin…
2016
St. John's Wort (Hypericum perforatum) is a perennial herb able to produce water-soluble active ingredients (a.i.), mostly in flowers, with a wide range of medicinal and biotechnological uses. However, information about the ability of arbuscular mycorrhizal fungi (AMF) to affect its biomass accumulation, flower production, and concentration of a.i. under contrasting nutrient availability is still scarce. In the present experiment, we evaluated the role of AMF on growth, flower production, and concentration of bioactive secondary metabolites (hypericin, pseudohypericin, and hyperforin) of H. perforatum under contrasting P availability. AMF stimulated the production of aboveground biomass und…
Molecular parameters involved in bee-plant relationships: a biological and chemical approach
1987
Abstract Honeybee-plant relationships are based on a conditioning process in which olfactory (plant aroma) and gustatory cues (mainly nectars) are closely linked, leading to a selective foraging behaviour. Among crops dependent upon entomophilous cross-pollination, the sunflower has recently undergone extensive expansion due to hybrid variety selection. Sunflower hybrid seed production is strictly dependent upon pollinating insects, mainly the honeybees, but foragers may have preferences among the parental lines, leading to a lack of pollen carriage and consequently to a decrease of hybrid seed yield. In order to define the role of plant chemicals (aromas, nectars) involved in the pollinati…
Cross inhibition improves activity selection when switching incurs time costs
2015
Abstract We consider a behavioural model of an animal choosing between two activities, based on positive feedback, and examine the effect of introducing cross inhibition between the motivations for the two activities. While cross-inhibition has previously been included in models of decision making, the question of what benefit it may provide to an animal’s activity selection behaviour has not previously been studied. In neuroscience and in collective behaviour cross-inhibition, and other equivalent means of coupling evidence-accumulating pathways, have been shown to approximate statistically-optimal decision-making and to adaptively break deadlock, thereby improving decision performance. Sw…
Phytochemical profiles, phototoxic and antioxidant properties of eleven Hypericum species - A comparative study
2018
Hypericum is one out of the nine genera belonging to the botanical family Clusiaceae Lindl (syn. Hypericaceae Juss.; APG III, 2009). The genus contains 484 species spread worldwide, one of which, Hypericum perforatum, is largely used in folk medicine. The aim of this study was to evaluate the chemical composition, along with the antioxidant and phototoxic activity, of 11 Hypericum species grown in Sicily (H. perforatum L., H. aegypticum L., H. androsaemum L., H. calycinum L., H. hircinum L., H. hirsutum L., H. montanum L., H. patulum Thunb., H. perfoliatum L., H. pubescens Boiss., H. tetrapterum Fr.). Samples of flowering tops collected from these Hypericum species were extracted and analys…
Diurnal timing of nonmigratory movement by birds: the importance of foraging spatial scales
2020
Timing of activity can reveal an organism's efforts to optimize foraging either by minimizing energy loss through passive movement or by maximizing energetic gain through foraging. Here, we assess whether signals of either of these strategies are detectable in the timing of activity of daily, local movements by birds. We compare the similarities of timing of movement activity among species using six temporal variables: start of activity relative to sunrise, end of activity relative to sunset, relative speed at midday, number of movement bouts, bout duration and proportion of active daytime hours. We test for the influence of flight mode and foraging habitat on the timing of movement activit…
Stable isotopes reveal differences in diet among reed bunting subspecies that vary in bill size
2017
Reed bunting Emberiza schoeniclus subspecies vary considerably in bill size and shape and seem to be at an early stage of speciation, in which bill might be indirectly causing reproductive isolation. Hence, we evaluated whether bill size, as well as age and sex, are associated with foraging niche in three west European subspecies of reed bunting: the thin-billed schoeniclus, the intermediate-billed lusitanica and the thick-billed witherbyi. Blood sampling was undertaken at three sites in southwest Europe during the winter (when these subspecies co-occur), and stable isotope analyses (carbon and nitrogen) were performed to assess their foraging niches. Stable isotope analyses of potential fo…