| 1. |
- Hedenström, Anders, et al.
(författare)
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Wing wear, aerodynamics and flight energetics in bumblebees (Bombus terrestris): an experimental study
- 2001
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Ingår i: Functional Ecology. - : Wiley. - 1365-2435 .- 0269-8463. ; 15:4, s. 417-422
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Tidskriftsartikel (refereegranskat)abstract
- I. Previous work has shown that wing wear increases mortality rate in bumblebees. Two proximate explanations have been suggested to account for this: increased energy flight costs and increased predation risk due to reduced manoeuvrability. 2. Wing wear was mimicked by experimentally clipping the forewing distal trailing edge, causing a 10% wing area reduction. Experimental and sham control bumblebees were induced to hover in a flight respirometry chamber for measuring metabolic rate of hovering. Simultaneous video and sound recordings were taken for wingbeat kinematic data required for an aerodynamic analysis. 3. In the experimental group with reduced wing area we measured increased wingbeat frequency, lift coefficient and induced power, but a reduced profile power. The mechanical power output, assuming perfect elastic storage in the flight system, remained largely unchanged after the wing-trimming treatment. 4. Metabolic flight costs (CO2 production rate) did not increase significantly in the reduced wing area group, which is in line with the aerodynamic power output. 5. Our results indicate that an increase of flight cost due to wing wear is not a likely explanation for increased mortality rate in bumblebees. Wing wear may, however, affect escape performance from predators.
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| 2. |
- Kvist, Anders, et al.
(författare)
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Basal metabolic rate in migratory waders: intra-individual, intraspecific, interspecific and seasonal variation
- 2001
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Ingår i: Functional Ecology. - : Wiley. - 1365-2435 .- 0269-8463. ; 15:4, s. 465-473
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Tidskriftsartikel (refereegranskat)abstract
- 1. Basal metabolic rates (BMR) were measured in 36 adult and 119 juvenile waders of 19 species on autumn migration in southern Sweden. 2. Ina comparison with literature data, it was found that juvenile BMR was generally lower than at the onset of migration in the Arctic and slightly higher than on African wintering grounds. 3. The seasonal differences may reflect local physiological adaptations or possibly a gradual decline from high premigratory levels due to growth. Our data contradict the idea that BMR is high during migration as an adaptation to generally high levels of energy expenditure. 4. The allometric exponent, scaling BMR to body mass, was significantly higher within individuals (1.19) and within species (1.82) than among species (0.62). 5. The high intra-individual exponent indicates that non-fat tissues, with a high metabolic activity, are involved in the mass changes during migratory stopover. 6. The high intraspecific exponent indicates that tissues with a high metabolic activity contributed disproportionately to variation in body mass among individuals or that larger individuals had elevated mass specific metabolic rates of some tissues.
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| 3. |
- Svanbäck, Richard, et al.
(författare)
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Morphology in perch affects habitat specific feeding efficiency
- 2004
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Ingår i: Functional Ecology. - : Wiley. - 0269-8463 .- 1365-2435. ; 18:4, s. 503-510
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Tidskriftsartikel (refereegranskat)abstract
- 1. Trophic polymorphism is a common phenomenon in many species. Trade-offs in foraging efficiency on different resources are thought to be a primary cause of such polymorphism. 2. To test for a trade-off in foraging efficiency perch (Perca fluviatilis L.) were used from a population that differs in morphology between the littoral and pelagic habitat of a lake. Indoor aquarium experiments were performed with three different prey types in two different environments. It was predicted that the morphology of the individual would affect foraging efficiency in the different environments and on the different prey types through search and attack behaviour. 3. Overall the foraging efficiency of perch was found to be related to individual morphology. A connection was also found between individual morphology and search and attack behaviour. Search behaviour but not attack behaviour was affected by the structure in the aquaria. Furthermore our results show that there are relations between search behaviour and detection rates and between attack behaviour and attack success. 4. Our results give a mechanistic explanation for the differences in foraging efficiency between littoral and pelagic perch. These differences are probably driven by a functional trade-off between foraging performance and general body form.
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| 4. |
- Dahlman, Lena, et al.
(författare)
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Growth in two foliose tripartite lichens Nephroma arcticum and Peltigera aphthosa : empirical modelling of external versus internal factors
- 2003
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Ingår i: Functional Ecology. - : Wiley. - 0269-8463 .- 1365-2435. ; 17:6, s. 821-831
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Tidskriftsartikel (refereegranskat)abstract
- 1 To assess how internal and external factors contribute to lichen growth, light, water and nutrient supplies were manipulated during 3 months in the field for the lichens Nephroma arcticum (L.) Torss. and Peltigera aphthosa (L.) Willd. Concomitant measures of weight and area gain, microclimatic conditions and investments in photobiont vs mycobiont tissue were also conducted. 2 In both lichens ≈80% of the variation in weight gain was explained by a linear regression model including light received during wet active periods, chlorophyll a concentration and area gain. All three parameters had a positive effect on weight gain. 3 About 80% of the variation in area gain was explained by a model including variation in weight gain, initial thallus specific weight, ergosterol and chitin concentration. The model was identical for the two lichens, with a positive effect of weight gain and thallus specific weight and a negative effect of ergosterol and chitin. 4 Peltigera aphthosa grew faster than N. arcticum when exposed to the same environmental conditions. This could be explained by its higher chlorophyll a to ergosterol ratio, and a greater water-holding capacity prolonging the active time in light.
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| 5. |
- Kullberg, Cecilia, et al.
(författare)
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Impaired flight ability prior to egg laying : A cost of being a capital breeder
- 2005
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Ingår i: Functional Ecology. - : Wiley. - 0269-8463 .- 1365-2435. ; 19:1, s. 98-101
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Tidskriftsartikel (refereegranskat)abstract
- 1To investigate flight ability in captive Zebra Finches during reproduction we compared change in escape take-off ability and wing load of reproducing females with their mates and non-reproducing females when attacked by a model raptor. 2Initially females had 18% higher wing load than males. Non-reproducing females and females that had started egg-laying flew slower than males. Reproducing females reduced wing load during egg-laying and flew faster when the clutch was completed. Non-breeding females remained on high wing load and flow slower than breeding females that had completed their clutch. 3The increase in flight speed of breeding females was explained by a reduction in wing load during egg-laying. 4Zebra Finches use accumulated reserves to produce eggs and pay a cost in terms of reduced flight ability, but then regain flight performance when the clutch is laid, probably demonstrating a predation cost of capital breeding in birds.
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| 6. |
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| 7. |
- Wiklund, Karin, et al.
(författare)
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Ecophysiological constraints on spore establishment in bryophytes
- 2004
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Ingår i: Functional Ecology. - : Wiley. - 0269-8463 .- 1365-2435. ; 18:6, s. 907-913
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Tidskriftsartikel (refereegranskat)abstract
- 1.Many threatened bryophytes are restricted to patchy and temporary substrates suchas dead wood and tree stems. Their persistence depends on successful colonizations ofnew patches. Spore germination may then be limited by substrate quality and wetness.2.In vitroexperiments were used to test the effects of pH and moisture on the establishmentof spores of the moss speciesNeckera pennataHedw. andBuxbaumia viridis(DC) Moug. & Nestl.3.Low pH and water potential prolonged the lag phase preceding germination andreduced final germination. The interaction between pH and moisture suggests that highwater availability facilitates germination at suboptimal pH, andvice versa.4.The results reflect the species’ habitats: the wood-inhabitingB. viridishad higher capacityto germinate at low pH, while spores of the epiphyteN. pennatashowed earlier germinationat low water potential and survived longer in a dry state. This supports the notionthat bryophytes are most strongly affected by substrate quality during establishment.5.We suggest that a trade-off exists among moss spores between the ability to colonizesubstrates with low moisture-holding capacity and low pH, and that the positive effectof high pH is largely that it speeds up germination thereby enabling the spores toexploit short, moist periods.
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| 8. |
- Abbey-Lee, Robin, et al.
(författare)
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Does perceived predation risk affect patterns of extra-pair paternity? A field experiment in a passerine bird
- 2018
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Ingår i: Functional Ecology. - : WILEY. - 0269-8463 .- 1365-2435. ; 32:4, s. 1001-1010
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Tidskriftsartikel (refereegranskat)abstract
- Non-consumptive predator effects have been shown to influence a wide range of behavioural, life history and morphological traits. Extra-pair reproduction is widespread among socially monogamous birds and may incur predation costs. Consequently, altered rates of extra-pair reproduction are expected in circumstances characterized by increased adult perceived predation risk. In addition, extra-pair reproduction is expected to be most affected for birds with phenotypes that generally increase predation risk (such as more active individuals). In two consecutive years, perceived predation risk was manipulated for great tits Parus major breeding in 12 nest-box plots by broadcasting sounds of their main predator (European sparrowhawk Accipiter nisus; six plots). As a control treatment, sounds of a sympatric, avian non-predator species were broadcast (Eurasian blackbird Turdus merula; six plots). Levels of extra-pair paternity did not differ between plots with different predation risk treatments. Males that moved more in a novel environment (more active or faster exploring) tended to have offspring with fewer partners, but this effect did not vary with predation risk treatment. From an adaptive viewpoint, predation costs associated with extra-pair reproduction may be small and may not outweigh the benefits of extra-pair behaviour. Research on a broader range of taxa with different mating strategies is now needed to confirm the generality of our findings.
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| 9. |
- Ahnesjö, Ingrid
(författare)
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Consequences Of Male Brood Care : Weight And Number Of Newborn In A Sex-Role Reversed Pipefish
- 1992
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Ingår i: Functional Ecology. - : JSTOR. - 0269-8463 .- 1365-2435. ; 6:3, s. 274-281
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Tidskriftsartikel (refereegranskat)abstract
- 1. In the pipefish Syngnathus typhle sex roles are reversed, as females compete for access to males. In this species males provide all brood care (i.e. are 'pregnant') and female reproductive rate exceeds the reproductive rate of males. Consequently females are limited by access to mates and male reproductive success is limited by male brooding ability and/or mate quality. Thus, phenomena like brood reduction and a trade-off between number and weight of newborn may be expected in males. 2. In this paper I demonstrate the following in males of S. typhle: (a) the initial weight of the egg (received from the female) positively influenced the weight of newborn; (b) in the male's brood pouch, number of newborn frequently is less than number of eggs initially received (brood reduction), and the extent of this decrease in brood size positively influenced the weight of newborn; (c) a trade-off between number and weight of newborn was demonstrated in males from field samples and in large experimental males (independent of brood reduction), but not in small males that presumably allocated resources to several other demands (condition, growth, etc.); (d) paternal length, per se, did not affect the weight of newborn. 3. The results indicate that in S. typhle, male reproductive success is limited by their own brooding ability and influenced by the egg size received (indirectly quality of mate), which may be expected in a situation of sex-role reversal.
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| 10. |
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