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- Coates, Melissa
(författare)
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Visual ecology and functional morphology of Cubozoa (Cnidaria)
- 2003
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Ingår i: Integrative and Comparative Biology. - : Oxford University Press (OUP). - 1557-7023 .- 1540-7063. ; 43:4, s. 542-548
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Tidskriftsartikel (refereegranskat)abstract
- Jellyfish belong to one of the oldest extant animal phyla, the Cnidaria. The first Cnidaria appear in the fossil record 600 million years ago, preceeding the Cambrian explosion. They are an extremely successful group present in all marine environments and some freshwater environments. In contrast to many animal phyla in which vision is a primary sense Cnidarians do not, generally, employ image forming eyes. One small class stands alone: the Cubozoa. Cubomedusae are commonly known as box jellyfish. They possess image forming eyes (Coates et al., 2001) which certainly evolved independently from other metazoans. Cubomedusae therefore offer a unique perspective on the evolution of image forming eyes. This literature review collects, into one place, what is known about: the multiple eye types of box jellyfish, cubomedusan life history and ecology, and the sensory and neural systems of box jellyfish. Here I discuss how these features set cubomedusae apart from scyphomedusae and hydromedusae. Knowledge in these areas is sparse; the work done to date inspires increased efforts.
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| 2. |
- Jones, Adam G., et al.
(författare)
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The measurement of sexual selection using Bateman's principles : An experimental test in the sex-role-reversed pipefish Syngnathus typhle
- 2005
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Ingår i: Integrative and Comparative Biology. - : Oxford University Press (OUP). - 1540-7063 .- 1557-7023. ; 45:5, s. 874-884
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Tidskriftsartikel (refereegranskat)abstract
- Angus J. Bateman's classic study of sexual selection in Drosophila melanogaster has had a major influence on the development of sexual selection theory. In some ways, Bateman's study has served a catalytic role by stimulating debate on sex roles, sexual conflict and other topics in sexual selection. However, there is still considerable disagreement regarding whether or not "Bateman's principles" are helpful in the study of sexual selection. Here, we test the idea that Bateman's principles provide the basis for a useful method to quantify and compare mating systems. In this study, we focus on the sex-role-reversed pipefish Syngnathus typhle as a model system to study the measurement of sexual selection. We set up artificial breeding assemblages of pipefish in the laboratory and used microsatellite markers to resolve parentage. Three different sex-ratio treatments (female-biased, even and male-biased) were used to manipulate the expected intensity of sexual selection. Measures of the mating system based on Bateman's principles were calculated and compared to the expected changes in the intensity of sexual selection. We also compare the results of this study to the results of a similar study of Bateman's principles in the rough-skinned newt, a species with conventional sex roles. The results of this experiment show that measures of the mating system based on Bateman's principles do accurately capture the relative intensities of sexual selection in the different treatments and species. Thus, widespread use of Bateman's principles to quantify mating systems in nature would facilitate comparative studies of sexual selection and mating system evolution.
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| 3. |
- Jönsson, K. Ingemar, 1959-
(författare)
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The evolution of life histories in holo-anhydrobiotic animals : a first approach
- 2005
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Ingår i: Integrative and Comparative Biology. - 1540-7063 .- 1557-7023. ; 45:5, s. 764-770
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Tidskriftsartikel (refereegranskat)abstract
- The life histories of holo-anhydrobiotic animals differ from those of all other organisms by a regular or irregular entrance into an ametabolic state induced by desiccation. Such ametabolic periods will arrest growth and reproduction completely and thus affect primary life history parameters dramatically. The selective forces and the genetic and physiological trade-offs acting on anhydrobiotic animals are to a large extent unknown. Assuming low growth rates and low juvenile to adult survival, general theoretical models on life history responses to stress predict that anhydrobiotic animals will be selected for a high degree of iteroparity, with low fecundity, large egg size, and low total reproductive investment. A high degree of variability in growth and reproduction should create a selective force in the same direction. Although basic empirical data on life history parameters are very scarce, available observations seem to be consistent with this prediction.
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| 4. |
- Kelber, Almut, et al.
(författare)
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Colour vision in diurnal and nocturnal hawkmoths
- 2003
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Ingår i: Integrative and Comparative Biology. - : Oxford University Press (OUP). - 1557-7023 .- 1540-7063. ; 43:4, s. 571-579
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Tidskriftsartikel (refereegranskat)abstract
- Diurnal and nocturnal hawkmoths (Sphingidae, Lepidoptera) have three spectral types of receptor sensitive to ultraviolet, blue and green light. As avid flower visitors and pollinators, they use olfactory and visual cues to find and recognise flowers. Moths of the diurnal species Macroglossum stellatarum and the nocturnal species Deilephila elpenor, Hyles lineata and Hyles gallii use and learn the colour of flowers. Nocturnal species can discriminate flowers at starlight intensities when humans and honeybees are colour-blind. M. stellatarum can use achromatic, intensity-related cues if colour cues are absent, and this is probably also true for D. elpenor. Both species can recognise colours even under a changed illumination colour.
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| 9. |
- Bok, Michael J., et al.
(författare)
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Here, There and Everywhere : The Radiolar Eyes of Fan Worms (Annelida, Sabellidae)
- 2016
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Ingår i: Integrative and Comparative Biology. - : Oxford University Press (OUP). - 1540-7063 .- 1557-7023. ; 56:5, s. 784-795
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Tidskriftsartikel (refereegranskat)abstract
- Fan worms (Annelida: Sabellidae) possess some of the strangest eyes in nature. Their eponymous fans are composed of two sets of radiolar tentacles that project from the head up out of the worm's protective tube into the water column. Primarily used for respiration and feeding, these radioles are also often involved in photoreception. They display a surprising diversity of eyes of varying levels of sophistication, ranging from scattered single ocelli to compound eyes with up to hundreds of facets. These photoreceptors could represent a relatively recent evolutionary development to cope with a sessile, tube-dwelling lifestyle, and the primary cerebral eyes (haplessly positioned within the tube most of the time) amount to little more than minute pigment cups with scant visual potential. The radiolar eyes on the other hand, appear to function as visual burglar alarms for detecting looming predators and eliciting a startle response for the worm to rapidly retreat within its fortified tube. Despite sometimes resembling arthropod compound eyes, the radiolar photoreceptors have many canonically vertebrate-like physiological characteristics. Considering the unusual and apparently recently evolved nature of the fan worm radiolar photoreceptors, these animals are an excellent case for examining the emergence of novel visual systems, the development of rudimentary visually guided behaviors, and the function of distributed sensory systems. Here, we review over 100 years of investigations into the anatomical diversity of sabellid radiolar photoreceptors and eyes in an evolutionary and functional context. We provide new information on radiolar eye structure in several species of fan worms, and we attempt to organize the various eye types and ocellar structures into meaningful hierarchies. We discuss the developmental, evolutionary, and functional significance of the radiolar eyes and highlight areas of future interest in deciphering their unique nature.
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