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- Arzel, Céline, et al.
(författare)
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Individual strategies of dabbling ducks : a circum-annual perspectice
- 2003
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Ingår i: Third North American duck symposium. ; , s. 73-
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Konferensbidrag (refereegranskat)abstract
- Very little is still known about the ecology of dabbling ducks on staging areas in spring, despite the fact that this is a crucial period of the year when birds refuel during migration and prepare for subsequent reproduction. This lack of knowledge translates into the current inability to predict the consequences of changes in the environment and harvesting for the population dynamics of ducks. We have launched a joint project to study dabbling ducks in the flyway connecting wintering grounds in France with breeding areas in Sweden. The aim is to study individual dabbling ducks in a circumannual perspective. We are assessing food resource limitation, density-dependent effects and the role of competition by estimating available food, by using a reference functional response curve and by recording the foraging behaviour of wild individual dabbling ducks. We also study survival probability and breeding success, and we will assess inter-individual variation. Birds are captured, weighed, marked and subsequently observed in order to study foraging behaviour and potentially measure the changes in body mass across time through recaptures. Ducks are fitted with nasal marks for individual recognition. Eventually, we will provide a model to predict the number of young that a female duck will produce after simple measurements such as its date of arrival on the breeding grounds and its body-mass at this date. Duckling foraging efficiency and survival will be measured and the relationship with corresponding estimates for their mother will be explored.
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| 2. |
- Bertolani, Roberto, et al.
(författare)
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Experiences with dormancy in tardigrades
- 2004
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Ingår i: Journal of limnology. - 1129-5767 .- 1723-8633. ; 63:Suppl. 1, s. 16-25
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Tidskriftsartikel (refereegranskat)abstract
- Tardigrades often colonise extreme habitats, in which they survive using both types of dormancy: quiescence and diapause. Together with nematodes and bdelloid rotifers, tardigrades are known to enter quiescence (with several forms of cryptobiosis: anhydrobiosis, cryobiosis, anoxybiosis, osmobiosis) at any stage of their life cycle, from egg to adult. Entering anhydrobiosis, tardigrades contract their body into a so-called tun, loosing most of their free and bound water (>95%), synthesizing cell protectants (e.g., trehalose, glycerol, heat shock proteins) and strongly reducing or suspending their metabolism. Our research on cryptobiosis focused on some ecological and evolutionary aspects. We evaluated: i) the long-term anhydrobiotic survival by comparing quantitative data on recovery from naturally induced desiccation in several species of tardigrades; ii) differences in survival patterns between species and populations by experimentally inducing anhydrobiosis and cryobiosis; iii) phenotypic factors affecting anhydrobiotic survival. As regards diapause, we considered encystment and eggs. Encystment involves at least the synthesis of new cuticular structures. Morphological changes during cyst formation are more complex than those involved in tun formation. We analyzed more in detail encystment processes, comparing a semiterrestrial with a limnic species. Several inter-specific differences have been identified, other than the production of two types of cysts in the semiterrestrial species. Our analysis of life history traits of a laboratory reared strain of a soil tardigrade revealed a particular hatching phenology that involved the production of both subitaneous and resting eggs. The latter need a cue to hatch (dehydration followed by re-hydration). In addition, the evolutionary meaning of dormancy in tardigrades is discussed
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| 3. |
- Elmberg, Johan, et al.
(författare)
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Andkonferens på prärien
- 2001
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Ingår i: Vår fågelvärld. - 0042-2649. ; 60:8, s. 25-
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 4. |
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| 8. |
- Elmberg, Johan, et al.
(författare)
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Hur påverkas andstammarna av jakt?
- 2000
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Ingår i: Jakt och jägare. - 1401-8306. ; 60:10, s. 44-45
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Tidskriftsartikel (populärvet., debatt m.m.)
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