| 1. |
- Ah-King, M., et al.
(författare)
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Why is there no sperm competition in a pipefish with externally brooding males? Insights from sperm activation and morphology
- 2006
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Ingår i: Journal of Fish Biology. - : Wiley. - 0022-1112 .- 1095-8649. ; 68:3, s. 958-962
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Tidskriftsartikel (refereegranskat)abstract
- Nerophis ophidion sperm activation and morphology were investigated with the aim of explaining the apparent lack of sperm competition in this syngnathid with externally brooding males. Nerophis ophidion sperm were activated by a mixture of ovarian fluid and sea water, but not by sea water alone. This indicated that sperm were not shed into the water but needed to be released near the eggs, which probably restrained sperm competition. (c) 2006 The Fisheries Society of the British Isles.
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| 2. |
- Kolm, Niclas, et al.
(författare)
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Do egg size and parental care coevolve in fish?
- 2005
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Ingår i: Journal of Fish Biology. - : Wiley. - 0022-1112 .- 1095-8649. ; 66:6, s. 1499-1515
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Tidskriftsartikel (refereegranskat)abstract
- A phenomenon that has attracted a substantial theoretical and empirical interest is the positive relationship between egg size and the extent of parental care in fishes. Interestingly, despite the effort put into solving the causality behind this relationship over the past two decades it remains largely unsolved. Moreover, how general the positive relationship between egg size and parental care is among fishes is also poorly understood. In order to stimulate research exploring egg size and parental care variation in fishes, the potential selective forces from both natural and sexual selection on egg size and parental care are discussed. Recent empirical findings on how oxygen requirements and developmental times may differ between differently sized eggs are incorporated into a critical view of the current theory of this field. Furthermore, it is suggested that the up to now neglected effects of sexual selection, through both mate choice and sexual conflict, can have strong effects on the relationship between egg size and parental care in fishes. In light of the recent developments of comparative and experimental methods, future approaches that may improve the understanding of the relationship between egg size and care in fishes are suggested.
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| 3. |
- Monteiro, N.M., et al.
(författare)
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Reproductive migrations of the sex role reversed pipefish Nerophis lumbriciformis (Pisces;Syngnathidae)
- 2006
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Ingår i: Journal of Fish Biology. - : Wiley. - 0022-1112 .- 1095-8649. ; 69:1, s. 66-74
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Tidskriftsartikel (refereegranskat)abstract
- Using an individual identification technique, a population of worm pipefish Nerophis lumbriciformis was followed during 19 months, in order to determine the exact use of the intertidal and, considering the specific movement patterns of males and females, the mating system exhibited by this population. Field observations showed that the number of adults increased during the breeding season, with males arriving 1 month earlier than females. Furthermore, males and females presented distinct permanence periods, showing that the intertidal is used as a mating arena. It was also observed that both male and female worm pipefish mated repeatedly over the span of a reproductive season, but females exhibited shorter remating intervals. Also, females stayed for longer periods on the mating grounds, the intertidal zone, whereas males typically left for the subtidal after mating, usually returning within 2 months. These inter-sexual differences in the occupation of the intertidal suggest that females breed with different males but also that males accept eggs from various females since, on their return, a new group of mating partners was now available. Thus, N. lumbriciformis might be considered polygynandric. It is a clearly dimorphic species in spite of the observed polygynandry, suggesting that differences in remating intervals may be influential in determining the strength of sexual selection along with what may be expected from the polygynandrous mating system alone.
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| 4. |
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| 5. |
- Ahnesjö, Ingrid
(författare)
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Behavioural temperature preference in a brooding male pipefish Syngnathus typhle
- 2008
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Ingår i: Journal of Fish Biology. - : Wiley. - 0022-1112 .- 1095-8649. ; 73:4, s. 1039-1045
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Tidskriftsartikel (refereegranskat)abstract
- In the broad-nosed pipefish Syngnathus typhle, brooding males positioned themselves significantly more often towards the warmer part (18 degrees C) of an aquarium. whereas females were indifferent in this respect. This behavioural temperature preference may increase male brooding rate and indirectly influence patterns of mating competition. (c) 2008 The Author Journal compilation (c) 2008 The Fisheries Society of the British Isles.
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| 6. |
- Bakke-McKellep, A. M., et al.
(författare)
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Effects of dietary soybean meal and photoperiod cycle on osmoregulation following seawater exposure in Atlantic salmon smolts
- 2006
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Ingår i: Journal of Fish Biology. - : Wiley. - 0022-1112 .- 1095-8649. ; 69:5, s. 1396-1426
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Tidskriftsartikel (refereegranskat)abstract
- Atlantic salmon Salmo salar juveniles were fed either fishmeal-based diets (FM) or diets in which soybean meal (SBM) partly replaced the FM from first feeding on. The fish were kept at continuous daylight during the juvenile stage. During the last 3 weeks before reaching 100 g body mass, all fish were subjected to 12L:12D. Starting at 100 g body mass, groups of 60 fish from each feeding background were subjected to continuous light for 12 weeks (short winter), or a square-wave photoperiod cycle to stimulate parr to smolt transformation with 8L:16D during the first 6 weeks, and then continuous light during the last 6 weeks (long winter). After the 12 weeks, 20 fish from each treatment were subjected to 0, 24 or 96 h seawater exposure at a water salinity of 34. Hypo-osmoregulatory ability at seawater exposure was assessed by mortality, intestinal pathology, plasma ion concentrations and osmolality, gill Na+/K+-ATPase activity and element concentrations in the cytoplasm of distal intestinal enterocytes using X-ray microanalysis. The hypo-osmoregulatory capacity was higher in fish kept at short winter than at long winter, apparently due to more rapid development of gill Na+/K+-ATPase activity. Fish fed SBM suffered typical soybean meal-induced histological alterations of the distal intestine and apparent reductions in digestive function in the more proximal gastrointestinal regions. The net osmoregulatory capacity of these fish was maintained, as indicated by higher gill Na+/K+-ATPase activity and lower plasma Na+, Ca2+ and osmolality compared to the FM-fed fish. Thus, feeding SBM did not impair the hypo-osmoregulatory ability of the Atlantic salmon following seawater exposure.
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| 7. |
- Björklund, Mats, et al.
(författare)
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Genetic differentiation in pikeperch (Sander lucioperca): the relative importance of gene flow, drift and common history
- 2007
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Ingår i: Journal of Fish Biology. - : Wiley. - 0022-1112 .- 1095-8649. ; 71:Suppl B, s. 264-278
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Tidskriftsartikel (refereegranskat)abstract
- To investigate the relative importance of homogenizing factors, such as gene flow, and diversifying factors, such as drift, genetic variation in pikeperch (Sander lucioperca) in two Fennoscandian regions (North and South) was analysed with microsatellites. Allelic richness and the degree of differentiation were significantly higher in the North (FST = 0·20) than in the South (FST = 0·064). In northern areas, assignments of genotypes were almost exclusively to the population of origin, but in southern areas, the proportion of correct assignments was significantly lower. Most samples exhibited significant heterozygote deficits, and the level of relatedness was higher than expected from randomness. These combined results suggest that there has been more gene flow between populations in southern areas than in northern areas, where the importance of genetic drift has been greater. Effective population sizes were small (c. 100) and did not differ between areas. The effect of a common history appears minor, and thus processes such as genetic drift and gene flow have been more influential in shaping the patterns of genetic diversity in this species.
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| 8. |
- Clark, T.D., et al.
(författare)
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Calibration of a hand-held haemoglobin analyser for use on fish blood
- 2008
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Ingår i: Journal of Fish Biology. - : Wiley. - 0022-1112 .- 1095-8649. ; 73:10, s. 2587-2595
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Tidskriftsartikel (refereegranskat)abstract
- The HemoCue haemoglobin analyser consistently overestimated haemoglobin concentration ([Hb]) in the blood of all fish species (sockeye salmon Oncorhynchus nerka, Chinook salmon Oncorhynchus tshawytscha, Pacific bluefin tuna Thunnus orientalis and chub mackerel Scomber japonicus) by 22–50% (9·9–36·0 g l−1) over a [Hb] range of 20–160 g l−1. The systematic nature of the overestimation, however, allowed the formulation of an accurate calibration equation that can be used to correct values of [Hb] measured by the HemoCue in field studies.
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| 9. |
- Demandt, Marnie, et al.
(författare)
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Loss of genetic variability in reintroduced roach (Rutilus rutilus) populations
- 2007
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Ingår i: Journal of Fish Biology. - : Wiley. - 0022-1112 .- 1095-8649. ; 70:Suppl.B, s. 255-261
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Tidskriftsartikel (refereegranskat)abstract
- Genetic variation at five microsatellite loci and in mtDNA was surveyed in reintroduced and 'control' populations of roach (Rutilus rutilus) in Sweden. Microsatellite allelic richness and allele size ranges were significantly reduced in reintroduced populations, and mtDNA diversity was nearly significantly reduced in reintroduced populations. These measures of genetic variability were strongly correlated with lake characteristics that influence population size and food availability.
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| 10. |
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