Search results for "Sign"
showing 10 items of 14733 documents
Evolution of signal diversity: predator-prey interactions and the maintenance of warning colour polymorphism in the wood tiger moth Arctia plantaginis
2017
Aposematic organisms avoid predation by advertising defences with warning signals. The theory of aposematism predicts warning signal uniformity, yet variation in warning coloration is widespread. The chemically defended wood tiger moth Arctia plantaginis shows both geographic variation and local polymorphism in warning coloration. In this thesis, I studied whether predation by local avian predators is driving the evolution of wood tiger moth warning colours. The close relatives of the wood tiger moth designated here to genus Arctia do not show similar colour polymorphism. The wood tiger moth is thus apparently under evolutionary radiation and provides a natural laboratory for observing curr…
Diversity in warning coloration: selective paradox or the norm?
2019
Aposematic theory has historically predicted that predators should select for warning signals to converge on a single form, as a result of frequency-dependent learning. However, widespread variation in warning signals is observed across closely related species, populations and, most problematically for evolutionary biologists, among individuals in the same population. Recent research has yielded an increased awareness of this diversity, challenging the paradigm of signal monomorphy in aposematic animals. Here we provide a comprehensive synthesis of these disparate lines of investigation, identifying within them three broad classes of explanation for variation in aposematic warning signals: …
Influence of colour, smell and taste on the survival of the wood tiger moth (Arctia plantaginis) adults during predation event
2021
Saalistajien torjumiseksi saalis voi käyttää erilaisia puolustusmekanismeja, jotka stimuloivat useita eri aisteja (ts. multimodaalista signalointia). Esimerkiksi aposemaattiset eliöt puolustautuvat varoitussignaalin lisäksi sekundaarisella puolustuksella. Tässä tutkimuksessa keskityttiin siihen, kuinka täpläsiilikkään (Arctia plantaginis) väritys (genotyypit WW, Wy ovat valkoisia ja yy keltaisia), haju (metoksipyratsiinista) ja maku (pyrrolitsidiinialkaloidista) toimivat puolustuksena lintusaalistajien hyökkäyksiä vastaan. Linnuille tarjottiin kummankin värisiä eläviä siilikkäitä, joita oli manipuloitu niin, että niillä oli joko hajua, makua tai molempia näistä. Näin pystyttiin tutkimaan ku…
Appearance before performance? : Nutritional constraints on life‐history traits, but not warning signal expression in aposematic moths
2020
1.Trade‐offs have been shown to play an important role in the divergence of mating strategies and sexual ornamentation, but their importance in explaining warning signal diversity has received less attention. In aposematic organisms, allocation costs of producing the conspicuous warning signal pigmentation under nutritional stress could potentially trade‐off with life‐history traits and maintain variation in warning colouration. 2. We studied this with an aposematic herbivore Arctia plantaginis (Arctiidae), whose larvae and adults show extensive variation in aposematic colouration. In larvae, less melanic colouration (i.e. larger orange patterns) produces a more efficient warning signal aga…
Multimodal Aposematic Signals and Their Emerging Role in Mate Attraction
2018
Virus-cell interactions as a pathological mechanism of parvovirus infection
2014
La Géométrie pour l'Unicité, la Parcimonie et l'Appariement des Estimateurs Pénalisés
2022
During the talk we will give a necessary and sufficient condition for the uniqueness of a penalized least squares estimator whose penalty term is a polyhedral norm. Our results cover many methods including the OSCAR, SLOPE and LASSO estimators as well as the related method of basis pursuit. The geometrical condition for uniqueness involves how the row span of the design matrix intersects the faces of the dual normunit ball. Theoretical results on sparsity by LASSO and basis pursuit estimators are deduced from this condition via the characterization of accessible sign vectors for these two methods.
Incidentality on a continuum: A comparative conceptualization of incidental news consumption
2020
This article seeks to contribute to theorizing the dynamics of incidental news consumption. Through an analysis of 200 semi-structured interviews with people in Argentina, Finland, Israel, Japan, and the United States, we show that intentionality in news consumption can be viewed on a continuum, which goes from deliberately setting apart time to access the news on specific outlets to skimming through unsought-for news on social and broadcast media, with intermediate practices such as respondents setting up an environment where they are more or less likely to encounter news. Drawing on structuration theory, this article conceptualizes incidental news in the context of the wider media environ…
Enhancing web course design using action research
2010
Applying Affordances Scale as a Design Method : Case Virtual Reality Course Design
2021
Practitioners including designers and teachers developing Virtual Reality (VR) courses are facing a question regarding the strengths and subject areas in which VR-enriched courses might have the highest potential compared to conventional courses. The present study develops a survey scale to assess and match industry managers’ requirements for skills for working life. The same scale was surveyed among two different groups of higher education students participating in conventional courses and a VR-aided course. The results indicate that the industry requirements were higher than met by the both course types. However, the results highlight a set of skills for which the VR courses have the high…