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| 2. |
- Bohlin, Titti, et al.
(författare)
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The detectability of the colour pattern in the aposematic firebug, Pyrrhocoris apterus : an image-based experiment with human 'predators'
- 2012
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 105:4, s. 806-816
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Tidskriftsartikel (refereegranskat)abstract
- Crypsis and aposematism are often regarded as two opposite protective strategies. However, there is large variation in prey appearance within both strategies. In this article, we investigated the conspicuousness of the aposematic red-and-black firebug, Pyrrhocoris apterus, by presenting images of natural and digitally manipulated phenotypes in their natural habitat on a computer screen to human predators, and comparing the detection times. We asked whether the natural colour pattern can be made more or less conspicuous by rearranging the spatial distribution of colour elements. Hence, we created a phenotype in which the black colour elements were moved to the body outline to test for a possible disruptive effect. In the black and red manipulations, we removed one of the two colours, creating two uniform colour variants. We found that some of our manipulations increased, but none reduced, the detection time significantly; this indicates that the naturally coloured firebug is highly conspicuous. The detection time varied among backgrounds and there was a significant relationship between detection time and chromatic similarity between the bug and the background for the natural and black phenotypes. Although background colour composition has an important effect on the signal, we argue that the coloration of P. apterus has evolved for high conspicuousness.
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| 3. |
- Bohlin, Titti, et al.
(författare)
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The effect of signal appearance and distance on detection risk in an aposematic butterfly larva (Parnassius apollo)
- 2008
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Ingår i: Animal Behaviour. - : Elsevier BV. - 0003-3472. ; 76, s. 577-584
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Tidskriftsartikel (refereegranskat)abstract
- Aposematic coloration commonly involves patterns with contrasting colours. The early larva of Parnassius apollo is uniformly black, but the later instars develop two rows of dorsal orange spots. We tested the effect of these orange markings on the conspicuousness of the last-instar larva, by manipulating larval coloration in photographs from a natural habitat and measuring how fast human subjects could discover the larva on a touch screen. In the first experiment we compared the detectability of the natural phenotype with that of manipulated uniformly black and uniformly orange variants at different distances. In the second experiment with another set of photographs we added manipulations involving enlarged and reduced spot sizes. Generally, detection time increased with distance, and decreased with the proportion of orange in the coloration. The uniformly black larvae were surprisingly hard to detect even at the closest distances, suggesting that the young black instar has an efficient camouflage. Furthermore, even a small amount of orange colour increased the conspicuousness of the larva considerably, indicating that the orange markings are costly in terms of detectability. Importantly, as the increase in detection time over distances was larger for the natural coloration than for the orange coloration, we suggest that the natural coloration may involve a distance-dependent switch from conspicuousness to camouflage with increasing distance. Thus, even though the orange markings most probably have a signalling function, the coloration is not maximized for either crypsis or conspicuousness.
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| 4. |
- Forsman, A, et al.
(författare)
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Fearful symmetry: pattern size and asymmetry affects aposematic signal efficacy
- 1999
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Ingår i: EVOLUTIONARY ECOLOGY. - : KLUWER ACADEMIC PUBL. - 0269-7653. ; 13:2, s. 131-140
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Tidskriftsartikel (refereegranskat)abstract
- Aposematic animals use anti-predator defence mechanisms such as distastefulness coupled with distinctive odours, sounds, or colour patterns to signal their unprofitability to potential predators. By subjecting artificial 'butterflies' with different visua
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| 5. |
- Jormalainen, V, et al.
(författare)
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Dynamics of intersexual conflict over precopulatory mate guarding in two populations of the isopod Idotea baltica
- 2000
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Ingår i: Animal Behaviour. - : Elsevier BV. - 1095-8282 .- 0003-3472. ; 60:1, s. 85-93
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Tidskriftsartikel (refereegranskat)abstract
- Aggressiveness during intersexual conflicts is predicted to depend on its costs, the value of winning and the power asymmetry of the contestants, all of which may vary between populations. In the marine isopod Idotea baltica (Pallas) a conflict occurs as females resist the attempts by males to start precopulatory mate guarding. We analysed contest dynamics with respect to female maturity stage, that is, to time left to reproductive moult, with which the payoffs of guarding for males and females change, We did this in two populations that differ in synchrony of reproduction, sex ratio and the degree of sexual dimorphism. The intensity and dynamics of contests differed between populations: in the more size-dimorphic population, females, the smaller sex, resisted less by forceful flexing but more by hooking their body than in the other population. Male aggressiveness stayed at a constant level with respect to female maturity. In the less size-dimorphic population, female resistance by flexing was intense and it decreased, while male persistence increased, with the approaching reproductive moult. Contests were more intense with small than with large males. These results fit well with the predictions from models of conflict behaviour. Assessment of the payoffs of winning versus contest costs, coadaptation of the level of aggressiveness to the other traits affecting contest outcome, and counteradaptations by the sexes to each other largely explain the dynamics and between-population differences of these contests. (C) 2000 The Association for the Study of Animal Behaviour.
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| 6. |
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| 7. |
- Kvarnemo, Charlotta, 1963, et al.
(författare)
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Mating distribution and its temporal dynamics affect operational sex ratio: a simulation study
- 2006
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066. ; 89:3, s. 551-559
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Tidskriftsartikel (refereegranskat)abstract
- The present study investigated how variation in mating distribution in time and among males influences the operational sex ratio (OSR) with a simulation inspired by paternally caring fish. Varying (1) the potential reproductive rate of each sex, (2) the mating distribution among males, and (3) the length of male mating phase, we created different mating patterns. In each case, we searched for the adult sex ratio that resulted in an OSR of 50% (where sex-roles switch). This approach enabled a comparison with a previous model. We found that the OSR was influenced by the distribution of matings in time and among males when the male mating phase was limited by a parental phase. Furthermore, the mating dynamics were shaped by the fact that the numbers of males and females and their capacities for collateral investment affected OSR immediately from the start of the reproductive season, whereas their times-out had a delayed effect on OSR. (c) 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 89, 551-559.
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| 8. |
- Merilaita, S
(författare)
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Crypsis through disruptive coloration in an isopod
- 1998
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Ingår i: PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON SERIES B-BIOLOGICAL SCIENCES. - : ROYAL SOC LONDON. - 0962-8452. ; 265:1401, s. 1059-1064
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The white-spotted colour morph of the marine isopod Idotea baltica appears cryptic on the brown alga Fucus vesiculosus with its white-coloured epizoites Electra crustulenta and Balanus improvisus. This study shows that the crypsis of this coloration is ac
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| 9. |
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| 10. |
- Merilaita, S, et al.
(författare)
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Optimization of cryptic coloration in heterogeneous habitats
- 1999
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Ingår i: BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY. - : ACADEMIC PRESS LTD. - 0024-4066. ; 67:2, s. 151-161
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We present a theoretical approach to the optimization of crypsis in heterogeneous habitats. Our model habitat consists of two different microhabitats, and the optimal combination of crypsis in the microhabitats is supposed to maximize the probability of e
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