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| 2. |
- Anderson, Peter, et al.
(författare)
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Root herbivory affects oviposition and feeding behavior of a foliar herbivore
- 2011
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 22, s. 1272-1277
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Tidskriftsartikel (refereegranskat)abstract
- Performance and distribution of phytophagous insects are driven by direct and indirect competitive interactions. Plant-feeding arthropods have been shown to interact indirectly through the plants' response to herbivory. In the case of systemically induced plant responses, this interaction extends to herbivores inhabiting different parts of a plant, for example, above- and belowground herbivores. Plant-induced responses elicited by root herbivores have been shown to affect feeding and development of aboveground herbivores. However, little is known about how root feeding affects host choice behavior of aboveground herbivores, including both adult oviposition behavior and larval host acceptance. Here, we report that root feeding by the wireworm, Agriotes lineatus, influences oviposition decisions and larval leaving rate of an aboveground herbivore, Spodoptera littoralis. In choice experiments, female S. littoralis deposited more and larger egg batches on undamaged plants when compared with wireworm-infested plants. In a larval feeding experiment, a higher percentage S. littoralis larvae moved away from the wireworm-infested plant onto a neighboring undamaged plant as compared with larvae feeding on previously undamaged plants. Larvae did not show an increased tendency to leave when feeding on plants previously exposed to conspecific larvae. Our results show that indirect interactions between belowground and aboveground herbivores extend to behavioral avoidance, both in terms of oviposition and larval feeding decisions. This allows the foliar herbivore to avoid systemic plant responses elicited by root herbivory, which likely represent reduced food quality and increased apparency toward natural enemies.
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| 3. |
- Aronsen, T., et al.
(författare)
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The operational sex ratio and density influence spatial relationships between breeding pipefish
- 2013
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 24:4, s. 888-897
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Tidskriftsartikel (refereegranskat)abstract
- The operational sex ratio (ratio of sexually receptive males to females) has been extensively studied in behavioral ecology, whereas other demographic factors such as the effect of density on mating behavior have received less empirical attention. We manipulated mating competition by establishing breeding populations of the sex-role reversed broad-nosed pipefish (Syngnathus typhle) at 2 sex ratios (male biased or female biased) and 2 densities. We used mean crowding (m*) and the index of association (X) to measure spatial distributions within and between the sexes, respectively, and investigated how these measures reflect the predicted strength of mating competition. In general, female m* increased as fewer males were available for mating, which suggests increased intrasexual competition in the most competitive sex. However, male m* also increased as the operational sex ratio became more female biased, suggesting that m* did not reflect mating competition for males. Association between the sexes (X) was higher under male bias than female bias, probably because males were still available for mating under male bias. In addition, X decreased in the female-biased treatment as the operational sex ratio became even more female biased. Higher density increased m* in both sex ratios and sexes, although for both sexes in the female-biased high-density treatment the operational sex ratio did not influence m*, probably because femalefemale competition inhibits further crowding in this treatment. In this study, we show that the use of m* and X can be a useful tool in behavioral studies but their interpretation requires detailed information about the mating system. Therefore, we recommend caution with their broadscale application.
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| 4. |
- Aronsson, Marianne, et al.
(författare)
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Evidence of signaling benefits to contrasting internal color boundaries in warning coloration
- 2013
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 24:2, s. 349-354
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Tidskriftsartikel (refereegranskat)abstract
- It has been suggested that the common existence of regular patterning in aposematic prey animals makes them stand out from the background, improving detection and recognition. Another suggestion is that internal patterns could have a similar positive effect on predator aversion learning as prey-to-background contrast. We used wild caught blue tits (Cyanistes caeruleus) and artificial prey signals to investigate if internal color boundaries, pattern regularity and pattern symmetry affect learning. Birds in different treatments were trained, on a complex background, to discriminate between artificial prey with different nonrewarding color stimuli with a black pattern and rewarding stimuli without a black pattern, followed by a generalization test. This study provides evidence of learning benefits to internally contrasting patterns as the striped prey stimuli were learned faster than the unstriped. Also, we found no beneficial effects of pattern regularity and symmetry. The birds generalized more between prey with different black patterns than to the profitable prey, suggesting that color is of foremost importance. The generalization test also showed a greater avoidance of striped than that of unstriped prey, suggesting some attention on patterns. Thus, internal patterning may affect signal salience and in some circumstances benefit prey due to both a faster avoidance learning and generalization behavior.
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| 5. |
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| 6. |
- Chapman, Ben, et al.
(författare)
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Unpredictability in food supply during early life influences boldness in fish
- 2010
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 21:3, s. 501-506
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Tidskriftsartikel (refereegranskat)abstract
- Behavioral variation has been documented both between and within populations in a variety of traits. Many of these behavioral traits are phenotypically plastic and are conditional on the early environment an animal experiences, yet despite this the role of the environment in generating variation in boldness is not well understood. Here we investigate the importance of early and recent experience of temporal unpredictability in food supply on the behavior of a species of freshwater fish, the Trinidadian guppy Poecilia mticulata. We predict that individuals that experience temporally unpredictable food supplies will engage in more risky behavior than those experiencing a Predictable food supply and find evidence to support this. Fish with early experience of unpredictable environments are generally bolder and more exploratory than fish reared in predictable environments, exploring a significantly greater proportion of a novel maze and spending less time in a refuge during the trial. Individuals with early experience of unpredictability also spent significantly less time associating with conspecifics in a shoaling tendency assay, again suggesting that they are bolder than guppies reared in predictable conditions. These findings suggest that early experience is important in shaping exploratory anti shoaling behavior in this species and that unpredictability in early life can influence boldness in guppies.
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| 7. |
- Dimitrova, Marina, et al.
(författare)
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Hide and seek : properties of prey and background patterns affect prey detection by blue tits
- 2014
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 25:2, s. 402-408
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Tidskriftsartikel (refereegranskat)abstract
- In prey camouflage, is it more important to match some aspects of background patterning than others? We studied detection of artificial prey by blue tits. Shape mismatch between prey and background pattern elements facilitated prey detection. Increased density of pattern elements in the background generally impeded prey detection, and mismatch in density between background and prey pattern elements also facilitated detection. This suggests that there are no shortcuts to effective background matching.We studied the effects of visual appearance of background and similarity between background and prey patterning on prey detection and camouflage. Although increased similarity with background (background matching) is known to impede prey detection, the relative importance of different aspects of visual similarity has received little interest. We used blue tits (Cyanistes caeruleus) as predators and trained them to search for artificial prey items presented on printed background plates. We particularly investigated the effect of the density and the shape of the elements constituting the background and the prey patterning. Our experiment shows that increase in the density of elements in the background caused an increase in search times of all prey types. We also found that compared with fully background-matching prey, prey patterning that sported a mismatching element shape and, interestingly, also prey patterning that mismatched the element density of the background decrease prey search time and, hence, deteriorated camouflage. There was no difference in search time between the shape- and the density-mismatching prey categories. We conclude that element-dense backgrounds are more protective both for background-matching prey and background-mismatching prey than backgrounds with low element density. Further, our results suggest that even if prey patterning consists of elements that closely match the visual elements in the background, high-level crypsis through background matching only arises if the density of the elements is also similar between the prey patterning and the background. These findings are important when considering prey habitat choice and the evolution and limitations of background matching and signaling coloration.
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| 8. |
- Dimitrova, Marina, et al.
(författare)
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Prey concealment : visual background complexity and prey contrast distribution
- 2010
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 21:1, s. 176-181
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Tidskriftsartikel (refereegranskat)abstract
- A prey may achieve camouflage through background matching and through disruptive coloration. Background matching is based on visual similarity between the prey and its background, whereas disruptive coloration emphasizes the use of highly contrasting pattern elements at the body outline to break up the body shape of the prey. Another factor that may influence prey detection, but has been little studied, is the appearance of the visual characteristics of the background. We taught blue tits (Cyanistes caeruleus) to search for artificial prey and manipulated the appearance of the prey and the background. We studied the effect of diversity of shapes in the background on prey detection time. We also studied the differing predictions from background matching and disruptive coloration with respect to contrast level and location of high-contrast elements in prey patterning. We found that visual background complexity did indeed increase prey detection time. We did not find differences in detection time among prey types. Hence, detection time was not affected by contrast within prey patterning, or whether the prey patterning matched only a sub-sample or all the shades present in the background. Also, we found no effect of the spatial distribution of shades (highest contrast placed marginally or centrally) on detection times. We conclude that background complexity is important for the evolution of prey coloration. We suggest that it may facilitate concealment and favor the evolution of camouflage over warning coloration. Preference for visually complex backgrounds might provide prey with a so far untested means to decrease predation risk.
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| 9. |
- Dimitrova, Marina, et al.
(författare)
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Prey pattern regularity and background complexity affect detectability of background-matching prey
- 2012
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 23:2, s. 384-390
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Tidskriftsartikel (refereegranskat)abstract
- We investigated how regularity of prey color pattern affects crypsis and how visual complexity of the background affects prey detection. We performed 2 predation experiments with artificial prey and backgrounds, using blue tits (Cyanistes caeruleus) as predators. In experiment 1, we found that contrary to a previous hypothesis, a pattern with repeated background-matching pattern element shapes was not easier to detect than a pattern with variable background-matching shapes. Increased background complexity with respect to shape diversity and complexity made prey detection more difficult. In experiment 2, we tested how spatial regularity of background-matching pattern elements affects crypsis. We found that spatially irregular prey with randomly placed pattern elements were harder to detect on both simple and complex backgrounds compared with spatially regular prey that had the elements aligned. Increased background element shape complexity made both prey categories harder to detect. In conclusion, our study shows that spatial regularity of prey pattern but not regularity due to invariable pattern element shapes deteriorates crypsis. Visually complex backgrounds and specifically those consisting of elements with complex shapes make detection of cryptic prey difficult.
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| 10. |
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