Search results for "AVOIDANCE"
showing 10 items of 297 documents
Predator experience on cryptic prey affects the survival of conspicuous aposematic prey.
2001
Initially, aposematism, which is an unprofitable trait, e.g. noxiousness conspicuously advertised to predators, appears to be a paradox since conspicuousness should increase predation by naive predators. However, reluctance of predators for eating novel prey (e.g. neophobia) might balance the initial predation caused by inexperienced predators. We tested the novelty effects on initial predation and avoidance learning in two separate conspicuousness levels of aposematic prey by using a 'novel world' method. Half of the wild great tits (Parus major) were trained to eat cryptic prey prior to the introduction of an aposematic prey, which potentially creates a bias against the aposematic morph. …
Co-mimics have a mutualistic relationship despite unequal defences
2007
Defensive mimicry, where species have evolved to resemble others in order to evade predators, is quite common in the animal kingdom. The two extremes of the mimicry spectrum are known as 'batesian' and 'mullerian'. Batesian mimics develop signals — visual cues for instance — that are similar to those of species being mimicked, but stop short of adopting the attribute that makes it unprofitable prey to predators. Mullerian mimics both resemble the model species and share the anti-predation attribute — by being dangerous or unpalatable. These different types of mimic were identified a century ago, but the dynamics of mimicry between unequally defended prey remain unresolved. In an experiment …
Can aposematic signals evolve by gradual change?
1999
Aposematic species, which signal conspicuously of their unprofitability to predators, have puzzled evolutionary biologists for over a century1,2. Although conspicuousness of unpalatable prey improves avoidance learning by predators3,4,5, it also involves an evolutionary paradox: with increasing detectability4,6,7,8 the deviant aposematic prey would suffer high predation initially from naive predators. Here we test a neglected idea7,8,9,10,11 that aposematic coloration may evolve by gradual change rather than by major mutations. Weak signals did not suffer high initial predation, but predators (great tits, Parus major) did not learn to separate them from cryptic palatable prey. Furthermore, …
A tale of 2 signals: signal mimicry between aposematic species enhances predator avoidance learning
2010
Mullerian mimicry, where 2 or more unrelated aposematic species resemble one another, is predicted to reduce the per capita mortality of co-mimics by allowing them to share the cost of educating nao ¨ve predators about their unpalatability. However, the specific assumptions and predictions of Muller's theory of shared resemblance have been previously unsupported; some authors have suggested that the benefits of signal similarity are undetectable or at best very small. We demonstrate clearly and un- ambiguously that mimicry between 2 defended forms can provide substantial protection from uneducated predators in the manner proposed originally by Muller. By utilizing prey signals that were des…
Multiple benefits of gregariousness cover detectability costs in aposematic aggregations
2001
Understanding the early evolution of aposematic (warning) coloration has been a challenge for scientists, as a new conspicuous morph in a population of cryptic insects would have a high predation risk and would probably die out before local predators learnt to avoid it1,2,3,4. Fisher5 presented the idea of aggregation benefit through the survival of related individuals; however, his theory has been strongly debated6,7,8 as the mechanisms that favour grouping have never been explored experimentally with the incorporation of detectability costs. Here we create a comprehensive ‘novel world’ experiment with the great tit (Parus major) as a predator to explore simultaneously the predation-relate…
Clima motivacional, metas de logro de aproximación y evitación y bienestar en futbolistas cadetes
2021
Basado en la teoría de las metas de logro (modelo dicotómico, Nicholls, 1989; y modelo 2 x 2, Elliot y McGregor, 2001), se exploró un modelo en el que se analizaban las relaciones hipotetizadas entre el clima motivacional percibido, la competencia percibida, las metas de maestría y resultado (aproximación y evitación), e indicadores positivos de bienestar (satisfacción con la vida y autoestima). Participaron 370 jóvenes varones jugadores de fútbol entre los 12 y los 16 años (M = 14,77). Los resultados mostraron una asociación positiva entre la percepción de un clima de implicación en la tarea y las orientaciones a la maestría (aproximación y evitación), y entre la percepción de un clima de …
Machine-learned selection of psychological questionnaire items relevant to the development of persistent pain after breast cancer surgery
2018
Background: Prevention of persistent pain after breast cancer surgery, via early identification of patients at high risk, is a clinical need. Psychological factors are among the most consistently proposed predictive parameters for the development of persistent pain. However, repeated use of long psychological questionnaires in this context may be exhaustive for a patient and inconvenient in everyday clinical practice. Methods: Supervised machine learning was used to create a short form of questionnaires that would provide the same predictive performance of pain persistence as the full questionnaires in a cohort of 1000 women followed up for 3 yr after breast cancer surgery. Machine-learned …
Temperamental characteristics in childhood migraine without aura: a multicenter study
2013
Maria Esposito,1 Rosa Marotta,2 Beatrice Gallai,3 Lucia Parisi,4 Giuseppina Patriciello,1 Serena Marianna Lavano,2 Giovanni Mazzotta,5 Michele Roccella,4 Marco Carotenuto11Center for Childhood Headache, Clinic of Child and Adolescent Neuropsychiatry, Department of Mental Health, Physical and Preventive Medicine, Second University of Naples, Naples, Italy; 2Department of Psychiatry, "Magna Graecia" University of Catanzaro, Catanzaro, Italy; 3Unit of Child and Adolescent Neuropsychiatry, University of Perugia, Perugia, Italy; 4Child Neuropsychiatry, Department of Psychology, University of Palermo, Palermo, Italy; 5Unit of Child and Adolescent Neuropsychiatry, AUSL Umbria 2, …
Behavioural studies on rats injected with l-cycloserine and other compounds
1964
l-cycloserine, a cyclic derivative of O-substituted hydroxylamine, causes the suppression of the conditioned avoidance reaction in the rat. The subsequent injection of equimolar amounts of pyridoxine hydrochloride is responsible for a complete reversal of this suppression. The suppression of the conditioned response is not observed with the d-isomer of cycloserine. Isoniazid is a strong antagonist of l-cycoserine. Changes in the brain level of GABA under several conditions are described. These changes suggest though do not establish a relationship between the block of the conditioned response and the elevation of the aminoacid above its physiological concentration.
The effects of castration and of progestin-oestrogen combinations upon avoidance condtioning in female rats
1970
Summary Using avoidance conditioning the authors show that female rats, three months after castration, emit a lower number of responses. Isolation has no effect whatever on rats, whether normal or castrated. Brief treatment with progestin-oestrogen combinations, interrupted 60 hours before the commencement of the session, brings the behaviour of castrated rats back to the norm. Identical effects occur with the use of a cortical stimulating drug (methylphenidate); while, the action of this drug soon ceases, the effect of hormonal treatment lasts for the duration of the experiments. The results are discussed with reference to the significance to be attributed to the experiments.