| 1. |
- Alerstam, Thomas, et al.
(författare)
-
Flight speeds among bird species : allometric and phylogenetic effects.
- 2007
-
Ingår i: PLoS biology. - : Public Library of Science (PLoS). - 1544-9173 .- 1545-7885. ; 5:8, s. e197-
-
Tidskriftsartikel (refereegranskat)abstract
- Flight speed is expected to increase with mass and wing loading among flying animals and aircraft for fundamental aerodynamic reasons. Assuming geometrical and dynamical similarity, cruising flight speed is predicted to vary as (body mass)(1/6) and (wing loading)(1/2) among bird species. To test these scaling rules and the general importance of mass and wing loading for bird flight speeds, we used tracking radar to measure flapping flight speeds of individuals or flocks of migrating birds visually identified to species as well as their altitude and winds at the altitudes where the birds were flying. Equivalent airspeeds (airspeeds corrected to sea level air density, Ue) of 138 species, ranging 0.01-10 kg in mass, were analysed in relation to biometry and phylogeny. Scaling exponents in relation to mass and wing loading were significantly smaller than predicted (about 0.12 and 0.32, respectively, with similar results for analyses based on species and independent phylogenetic contrasts). These low scaling exponents may be the result of evolutionary restrictions on bird flight-speed range, counteracting too slow flight speeds among species with low wing loading and too fast speeds among species with high wing loading. This compression of speed range is partly attained through geometric differences, with aspect ratio showing a positive relationship with body mass and wing loading, but additional factors are required to fully explain the small scaling exponent of Ue in relation to wing loading. Furthermore, mass and wing loading accounted for only a limited proportion of the variation in Ue. Phylogeny was a powerful factor, in combination with wing loading, to account for the variation in Ue. These results demonstrate that functional flight adaptations and constraints associated with different evolutionary lineages have an important influence on cruising flapping flight speed that goes beyond the general aerodynamic scaling effects of mass and wing loading.
|
|
| 2. |
|
|
| 3. |
- Alström, Per, Professor, et al.
(författare)
-
Phylogeny and classification of the avian superfamily Sylvioidea
- 2006
-
Ingår i: Molecular Phylogenetics and Evolution. - Swedish Museum Nat Hist, Dept Vertebrate Zool, SE-10405 Stockholm, Sweden. Swedish Museum Nat Hist, Mol Systemat Lab, SE-10405 Stockholm, Sweden. Uppsala Univ, Evolutionary Biol Ctr, Dept Systemat Zool, SE-75236 Uppsala, Sweden. Univ Gothenburg, Dept Zool, SE-40530 Gothenburg, Sweden. : Elsevier BV. - 1055-7903 .- 1095-9513. ; 38:2, s. 381-397
-
Tidskriftsartikel (refereegranskat)abstract
- Sylvioidea is one of the three superfamilies recognized within the largest avian radiation, the parvorder Passerida. In the present study, which is the first taxon-dense analysis of the Sylvioidea based on sequence data (nuclear myoglobin intron II and mitochondrial cytochrome b gene), we investigate the interrelationships among the four "sylvioid" clades found by previous workers, as well as the relationships within the largest of these clades. The nuclear and mitochondrial loci estimate basically the same phylogeny, with minor differences in resolution. The trees based on myoglobin and the combined data identify a strongly supported clade that includes the taxa previously allocated to Sylvioidea, except for Sitta (nuthatches), Certhia (treecreepers), Parus (tits), Remiz (penduline tits), Troglodytes and Campylorhynchus (wrens), Polioptila (gnatcatchers), and Regulus (crests/kinglets); this clade also comprises larks, which have previously been placed in the superfamily Passeroidea. We refer to this clade as Sylvioidea. This clade is further divided into 10 main, well-supported clades, which we suggest form the basis for a revised classification. (c) 2005 Elsevier Inc. All rights reserved.
|
|
| 4. |
- Andersson, Ki, et al.
(författare)
-
Carnivora from the Late Miocene of Lantian, China
- 2005
-
Ingår i: Vertebrata PalAsiatica. ; 43, s. 256-271
-
Tidskriftsartikel (refereegranskat)abstract
- Sediments of the Bahe and Lantian formations, Lantian area, Shaanxi Province, China, have produced a large number of mammalian fossils. This Late Miocene sequence provides evidence for a period of major changes in the physical environment of the region. The carnivoran fossils are described and analyzed herein. The following species are present: lctitherium viverrinum, Hyaenictitherium cf . H. wongii and Adcrocuta eximia ( Hyaenidae) , cf. Metailurus major and cf. Metailurus parvulus ( Felidae) . Although a difference in the composition of the carnivoran fauna is noted towards the boundary between the Bahe Formation (lower) and Lantian Formation (upper), the cause of this is yet to be determined.
|
|
| 5. |
- Bartsch, Hans, et al.
(författare)
-
Dyster svävfluga åter i farten i Dalarna
- 2007
-
Ingår i: Fauna och flora. - 0014-8903. ; 102:3, s. 50-54
-
Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Villa occulata was found in a bog in the province of Dalarna, Sweden in 2005 and 2006. Extended search for the species in 2007 showed it to be regularly present in similar mires in the same area. This indicates that the species is resident in Sweden and opens the possibility for further studies of its poorly known distribution and biology. The species seems to be confined to bogs which may explain why it has gone largely unnoticed. The paper summarizes the present state of knowledge.
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
- Björling, T., et al.
(författare)
-
SrAlSiH : A polyanionic semiconductor hydride
- 2005
-
Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 44:44, s. 7269-7273
-
Tidskriftsartikel (refereegranskat)abstract
- (Chemical Equation Presented) Stable and semiconducting: Polyanionic hydrides represent a new class of main-group-metal hydrides with unforeseen hydrogen-coordination environments. The hydrogen atom in SrAlSiH is attached exclusively to Al and forms part of a layered [AlHSi]2- polyanion (see figure). This material is the first narrow bandgap semiconductor hydride and combines the high thermal stability of saline hydrides with the air and moisture stability of interstitial transition-metal hydrides.
|
|
| 9. |
|
|
| 10. |
|
|
