Search results for "Systematic"
showing 10 items of 7608 documents
Studies on the effects of Ca2++ and Co++ on the swimming behavior of the blind Mexican cave fish
1992
The hypothesis that the blind cave fish (Astyanax hubbsi) adjusts the level of stimulation to its lateral line system (LLS) by varying its own velocity was examined. When the sensitivity of the LLS sense organs was reduced by lowering the Ca2+ concentration in the water or by adding Co2+ the fish compensated for this by swimming at a higher velocity.
Allium aetnense (Amaryllidaceae), a new species from Sicily.
2013
A new species from Mt Etna (Sicily), Allium aetenense of A. sect. Codonoprasum, is described and illustrated. It is a diploid species (2n = 16) that grows on basaltic rocks in the mountain belt and shows close relationships with A. tenuiflorum of the Italian peninsula. Its morphology, karyology, leaf anatomy, seed coat microsculpturing, ecology and taxonomic position are examined.
On the discrimination of spatial intervals by the blind cave fish (Anoptichthys jordani).
1986
The performance of the blind cave fish in discriminating spatial intervals was investigated. The fish had to discriminate between pairs of grids consisting of equidistant vertical bars. The intervals between the bars on the grid to be chosen were kept constant while the intervals between the bars on the other grid were altered in steps so as to become gradually closer to the interval between the bars on the grid to be chosen. It was found that the fish were still able to discriminate between the two grids when the difference between the bar intervals amounted to at least 1.5 mm. In interpreting the results it was concluded that the phase information in the stimulus on the skin of the fish m…
Learning and remembering the environment in the blind cave fishAnoptichthys jordani
1989
1. The swimming behavior of blind cave fish (Anoptichthys jordani) differs in familiar and unfamiliar surroundings. Following release in unfamiliar surroundings, or after alterations of a familiar environment, the fish increase swimming velocity in order to optimize lateral line organ stimulation. Furthermore, they glide along boundary features more often than they do in familiar surroundings. These characteristics of swimming behavior were used to measure the occurrence and duration of exploratory behavior. 2. Fish removed from a familiar environment for as long as 2 days spend less time exploring when returned than when they were initially placed in the environment. After a longer absence…
Detection of stationary objects by the blind Cave FishAnoptichthys jordani (Characidae)
1981
It was noticed that the blind Mexican Cave Fish repeatedly passes along objects new to it at a short distance. Observations and experiments are reported which support the hypothesis that water movements occurring between the stationary object and the fish as it passes by convey information about the location and possibly the shape of the object, which is detected by the lateral line organ of the fish. Water movements of the expected type were recorded with the help of a model fish equipped with a mechano-electric analogue of a free neuromast.
Stability and endemicity of benthic diatom assemblages from different substrates in a maritime stream on Byers Peninsula, Livingston Island, Antarcti…
2013
16 páginas, 3 tablas, 9 figuras.
Yttrium and REE signature recognized in Central Mediterranean Sea (ODP Site 963) during the MIS 6–MIS 5 transition
2010
Abstract The Mediterranean Sea acts as a miniature ocean with the development of its own conveyor belt. It constitutes an ideal location to study and forecast how the marine environment responds to rapid climatic change. Here we present a palaeoenvironmental study carried out on the sediments of ODP Site 963, recovered in the Sicily Channel, the sill which divides the western from the eastern Mediterranean basin. We focused on the transition between the penultimate glacial (MIS 6) and the last interglacial (MIS 5), between approximately 130 and 115 kyr BP. A novel approach is proposed, taking into account centennial-scale geochemical data on major elements, selected trace elements, and yttr…
The Leiza palaeo-fault: Role and importance in the Upper Cretaceous sedimentation and palaeogeography of the Basque Pyrenees (Spain)
1999
Abstract New analysis of the Upper Cretaceous deposits of the Central Depression, a syncline within the Basque Pyrenees, shows that this structure was a deep marine basin analogous to the regional flysch troughs. It was bounded by active faults, including the Leiza palaeo-fault, which sustained erosion of the partly subaerially exposed margins. The Leiza palaeo-fault and its western counterpart, the Kalamua palaeo-fault, are thought to constitute the former plate boundary between Iberia and Europe, and a westward continuation of the North Pyrenean Palaeo-Fault.
Exploring land snails’ response to habitat characteristics and their potential as bioindicators of riparian forest quality
2021
Abstract Riparian ecosystems are crucial for landscape-level biodiversity, especially in highly anthropic and agricultural areas. Although the low mobility of snails reduces their dispersal capacity and makes them vulnerable to habitat degradation, they are less commonly used as indicators. We evaluated the potential of land snails as bioindicators of riparian forest quality in central European riparian forests by surveying snail communities in relation to habitat characteristics that characterize its quality. Habitat characteristics were found to affect both snail abundance and species richness. The abundance of snail species increased with the forest continuity, forest width and abundance…
Estimating natal dispersal movement rates of female European ducks with multistate modelling
2003
Summary 1 We used up to 34 years of capture–recapture data from about 22 100 new releases of day-old female ducklings and multistate modelling to test predictions about the influence of environmental, habitat and management factors on natal dispersal probability of three species of ducks within the Engure Marsh, Latvia. 2 The mean natal dispersal distances were very similar (c. 0·6–0·7 km) for all three species and were on average 2·7 times greater than breeding dispersal distances recorded within the same study system. 3 We were unable to confirm the kinship hypothesis and found no evidence that young first-nesting females nested closer to their relatives (either mother or sister) than to …