Direct male-male competition can facilitate invasion of new colour types in Lake Victoria cichlids

The possibility that disruptive sexual selection alone can cause sympatric speciation is currently a subject of much debate. The initial difficulty for new and rare ornament phenotypes to invade a population, and the stabilisation of the resulting polymorphism in trait and preference make this hypothesis problematic. Recent theoretical work indicates that the invasion is facilitated if males with the new phenotype have an initial advantage in male-male competition. We studied a pair of sympatric incipient species of cichlids from Lake Victoria, in which the red (Pundamilia nyererei) and blue males (P. pundamilia) vigorously defend territories. Other studies suggested that red phenotypes may have repeatedly invaded blue populations in independent episodes of speciation. We hypothesised that red coloration confers an advantage in male-male competition, assisting red phenotypes to invade. To test this hypothesis, we staged contests between red and blue males from a population where the phenotypes are interbreeding morphs or incipient species. We staged contests under both white and green light condition. Green light effectively masks the difference between red and blue coloration. Red males dominated blue males under white light, but their competitive advantage was significantly diminished under green light. Contests were shorter when colour differences were visible. Experience of blue males with red males did not affect the outcome of a contest. The advantage of red over blue in combats may assist the red phenotype to invade blue populations. The apparently stable co-existence of red and blue incipient species in many populations of Lake Victoria cichlids is discussed.

Das Abenteuer Bildung. Über Pflicht, Lust und Ideen im Lauf der Zeit

Kindergarten, Schule, Aus- und Weiterbildung, individuelle Interessen, Neugier und Forscherdrang – Bildung begleitet uns ein Leben lang. Sie ist das wertvollste Gut einer Gesellschaft, denn in ihr geben wir Wissen und Werte, Kompetenzen und Kreativität weiter: die Basis gesellschaftlicher Innovation. Die Ausstellung lädt ein zu einer Entdeckungsreise durch die unterschiedlichen Dimensionen von Bildung in Geschichte und Gegenwart, stellt sie auf die Probe und fragt danach, welche Bildung wir uns für die Zukunft wünschen.

Halbzeit. Ein Blick auf die Mitte des Lebens. Ausstellung im Vögele Kultur Zentrum, Pfäffikon/SZ

Viele Menschen erleben das mittlere Alter als eine spannende, teils auch bedrängende Übergangszeit. Die Erfahrung des langsamen körperlichen Alterns, der Verlust von jugendlicher Schönheit und körperlicher Kraft zeigen an, dass die eigene Lebenszeit nicht unbegrenzt ist. Damit rückt die Frage ins Zentrum, wie die verbleibende Zeit am besten zu nutzen ist. Neuorientierungen in Partnerschaft und Beruf können die Folge sein. Die individuellen Werte können sich deutlich verschieben. Im Gegensatz zur Jugend und dem höheren Alter hat das mittlere Alter bisher in der Öffentlichkeit weniger Beachtung gefunden. Als erste umfassende Ausstellung zur Thematik bietet die Ausstellung «Halbzeit» eine vertiefte Auseinandersetzung mit der Phase des Übergangs von der Jugend zum Alter. Sie vereinigt künstlerische Positionen, Interviews mit Menschen im mittleren Alter und zahlreiche Sachexponate zu einem interaktiven Erlebnis- und Erfahrungsraum.

Probabilistic approach to cloud and snow detection on Advanced Very High Resolution Radiometer (AVHRR) imagery

Derivation of probability estimates complementary to geophysical data sets has gained special attention over the last years. Information about a confidence level of provided physical quantities is required to construct an error budget of higher-level products and to correctly interpret final results of a particular analysis. Regarding the generation of products based on satellite data a common input consists of a cloud mask which allows discrimination between surface and cloud signals. Further the surface information is divided between snow and snow-free components. At any step of this discrimination process a misclassification in a cloud/snow mask propagates to higher-level products and may alter their usability. Within this scope a novel probabilistic cloud mask (PCM) algorithm suited for the 1 km × 1 km Advanced Very High Resolution Radiometer (AVHRR) data is proposed which provides three types of probability estimates between: cloudy/clear-sky, cloudy/snow and clear-sky/snow conditions. As opposed to the majority of available techniques which are usually based on the decision-tree approach in the PCM algorithm all spectral, angular and ancillary information is used in a single step to retrieve probability estimates from the precomputed look-up tables (LUTs). Moreover, the issue of derivation of a single threshold value for a spectral test was overcome by the concept of multidimensional information space which is divided into small bins by an extensive set of intervals. The discrimination between snow and ice clouds and detection of broken, thin clouds was enhanced by means of the invariant coordinate system (ICS) transformation. The study area covers a wide range of environmental conditions spanning from Iceland through central Europe to northern parts of Africa which exhibit diverse difficulties for cloud/snow masking algorithms. The retrieved PCM cloud classification was compared to the Polar Platform System (PPS) version 2012 and Moderate Resolution Imaging Spectroradiometer (MODIS) collection 6 cloud masks, SYNOP (surface synoptic observations) weather reports, Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) vertical feature mask version 3 and to MODIS collection 5 snow mask. The outcomes of conducted analyses proved fine detection skills of the PCM method with results comparable to or better than the reference PPS algorithm.

Ein Dolmen in der Schweiz

Ende 2011 erhielt der Archäologische Dienst des Kanton Bern die telefonische Mitteilung, im Dorfkern von Oberbipp kämen bei Baggerarbeiten grosse Steinblöcke und zahlreiche Knochen zum Vorschein. Bereits beim ersten Besuch liess sich eine jungsteinzeitliche Dolmenanlage erkennen.

Hippocampus is place of interaction between unconscious and conscious memories retrieval

Recent experiments suggest that humans can form and later retrieve new semantic relations unconsciously by way of hippocampus - the key structure thought to support conscious relational (episodic) memory. Given that the hippocampus subserves both conscious and unconscious relational encoding/retrieval, we expected the hippocampus to be place of unconscious-conscious interactions. This hypothesis was tested in an fMRI experiment on the interaction between the unconscious retrieval of face-associated occupations and the subsequent conscious retrieval of celebrities’ occupations. For subliminal encoding, masked combinations of an unfamiliar face and a written occupation (“actor” or “politician”) were subliminally presented. At test, we presented the former subliminal faces again, without occupations and masks, as conscious retrieval cues. We hypothesized that faces would trigger the unconscious reactivation of the associated occupation - actor or politician -, which in turn would facilitate or inhibit the subsequent conscious recollection of a celebrity’s occupation. Following the presentation of a former subliminal face, we presented the portrait of a celebrity that participants were required to sort according to “actor” or “politician”. Depending on whether the triggered unconscious occupation was congruent or incongruent with the celebrity’s occupation, we expected an expedited or retarded conscious retrieval process as reflected in reaction times. Conscious retrieval was expedited in the congruent condition, but there was no effect in the incongruent condition. fMRI data collected during subliminal relational encoding confirmed that the hippocampus was interacting with neocortical semantic storage sites. fMRI data collected at test indicated that the facilitated conscious retrieval of celebrity-associated occupations was related to deactivations in this same network spanning hippocampus and neocortical semantic storage sites. Hence, unconscious retrieval likely preactivated this network, which allowed for a sparing recruitment of additional neural resources to assist conscious retrieval. This finding supports the notion that consciously and unconsciously acquired relational memories are stored in a single, cohesive hippocampal-neocortical memory space.