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- Hettyey, Attila, et al.
(författare)
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Body temperature, size, nuptial colouration and mating success in male Moor Frogs (Rana arvalis)
- 2009
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Ingår i: Amphibia-Reptilia. - 0173-5373 .- 1568-5381. ; 30:1, s. 37-43
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Tidskriftsartikel (refereegranskat)abstract
- Variation in colouration has rarely been related to sexual Selection ill anuran amphibians, even though such a relationship has been proven for many other vertebrate taxa. Male and female Moor Frogs (Rana arvalis) have a cryptic brown colour pattern, but males develop a conspicuous blue nuptial colouration during the reproductive season. To investigate: the possibility that colouration plays a role in sexual selection in this species, we Studied the temporal variation in blue colouration. determined if body size or body temperature affected blueness and investigated if blueness of males could be related to their mating, success. Results confirmed previous observation,,, that males develop and maintain blue colouration for only a very few nights during peak reproductive activity. Colouration of males was unrelated to body size, but males exhibiting higher body temperatures were somewhat bluer (hall males with lower body temperatures. Further, males in amplexus had higher body temperatures than non-mated males. Finally, Mating Success Was positively related to blueness in small males, whereas in large males no such relationship was detected. While our results align with the hypothesis that the bright blue colouration of males may be a target of sexual selection. alternative explanations are also discussed.
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| 2. |
- Hettyey, Attila, et al.
(författare)
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Does testis weight decline towards the Subarctic? : a case study on the common frog, Rana temporaria
- 2005
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Ingår i: Die Naturwissenschaften. - 0028-1042 .- 1432-1904. ; 92:4, s. 188-192
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Tidskriftsartikel (refereegranskat)abstract
- Interpopulation comparisons of variation in resource availability and in allocation patterns along altitudinal and latitudinal gradients allow insights into the mechanisms shaping the life history of animals. Patterns of between-population differences in female life history traits have been studied intensively across a wide range of taxa, but similar investigations in males have remained scarce. To study if testis weight-a measure of reproductive investment-varies on a geographical scale in anurans, we focussed on the variation in relative testis weight (RelTW) and asymmetry in 22 populations of the common frog Rana temporaria along a 1,600-km latitudinal transect across the Scandinavian peninsula. We found that RelTW decreased towards the north. Body mass and body length both had independent positive effects on testes mass. We found evidence for directional asymmetry (DA) in testis weight with the right testis being larger than the left. The level of DA in testis weight was not related to latitude, but both body mass and testes mass had independent positive effects on asymmetry. We discuss the northwards decrease in RelTW in terms of a decreased reproductive investment as a possible consequence of harsher environmental conditions, and perhaps also, weaker sexual selection in the north than in the south.
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| 3. |
- Hettyey, Attila, et al.
(författare)
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Interactions between the information content of different chemical cues affect induced defences in tadpoles
- 2010
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Ingår i: Oikos. - : Wiley. - 0030-1299 .- 1600-0706. ; 119:11, s. 1814-1822
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Tidskriftsartikel (refereegranskat)abstract
- Animals often alter their behaviour, morphology and physiology in the presence of predators. These induced defences can be fine-tuned by a variety of environmental factors such as predator species, acute predation risk or food availability. It has, however, remained unclear what cues influence the extent and quality of induced defences and how the information content of these cues interact to determine the development of antipredator defences. We performed an experiment to study the significance of direct chemical cues, originating from the predators themselves, and indirect cues, released by attacked or consumed prey, for phenotypic responses in Rana dalmatina tadpoles. We reared tadpoles in the presence of caged predators (Triturus vulgaris, Aeshna cyanea) fed either one or three tadpoles every other day outside the tadpole-rearing tanks. Fifteen hours after food provisioning, predators were put back into the tanks containing focal tadpoles either after washing (direct + digestion-released cues) or with the water containing remnants of the prey (direct + all types of indirect cues). Our results suggest that direct cues together with digestion-released cues can be sufficient to induce strong antipredator responses. Induced defences depended on both direct cues, affecting predator-specific responses, and the quantity of indirect cues, resulting in graded responses to differences in predation threat. Moreover, direct and indirect cues interacted in behaviour, resulting in predator-specific graded responses. We also observed a decrease in the extent of predator-induced responses in large tadpoles as compared to small ones. Our results, thus, suggest that prey integrate multiple cues about predators to optimize induced defences and that this process changes during ontogeny.
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