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- Salomon, Björn, et al.
(författare)
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Evolutionary process of Hordeum brachyantherum 6x and related tetraploid species revealed by nuclear DNA sequences
- 2009
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Ingår i: Breeding Science. - : Japanese Society of Breeding. - 1344-7610 .- 1347-3735. ; 59, s. 611-616
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Tidskriftsartikel (refereegranskat)abstract
- A hexaploid form of Hordeum brachlyantherum ssp. brachyantherum was discovered in California in 1980, and its origin has since been studied over the past three decades. We applied EF-G, a nuclear DNA sequence, to infer the parents of the hexaploid form. In polyploid taxa, amplified DNAs were cloned into a vector, and EF-G copies were amplified from the colonies by PCR and digested with restriction enzymes to separate different types. Phylogenetic analysis was performed based on the DNA sequences. The result showed that H. brachyantherum ssp. brachyantherum 6x and 4x carried one identical DNA sequence of 910 bp, and had closely related DNA sequences of 931 bp. H. brachyantherum ssp. brachyantherum 6x and H. marinum ssp. gussoneanum 2x shared one identical DNA sequence of 915 bp. From these results we hypothesized that H. brachyantherum ssp. brachyantherum 6x has evolved by an outcrossing between H. marinum ssp. gussoneanum 2x and H. brachyantherum ssp. brachyantherum 4x, followed by a chromosome doubling. Our results also indicate that H. marinum was involved in the polyploidization of H. secalinum, H. capense, and H. marinum. The origins of H. jubatum and H. depressum are discussed.
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- Messing, Ingmar, et al.
(författare)
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Bygg inte på kultur- och åkermark
- 2009
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Ingår i: Upsala nya tidning. - Uppsala. - 1104-0173. ; :2 maj, s. 4-
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Tidskriftsartikel (populärvet., debatt m.m.)
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- Ranius, Thomas, et al.
(författare)
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Development of tree hollows in pedunculate oak (Quercus robur)
- 2009
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 257, s. 303-310
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Tidskriftsartikel (refereegranskat)abstract
- Many invertebrates, birds and mammals are dependent on hollow trees. For landscape planning that aims at persistence of species inhabiting hollow trees it is crucial to understand the development of such trees. In this study we constructed an individual-based simulation model to predict diameter distribution and formation of hollows in oak tree populations. Based on tree ring data from individual trees, we estimated the ages when hollow formation commences for pedunculate oak (Quercus robur) in southeast Sweden. At ages of about 200-300 years, 50% of the trees had hollows. Among trees < 100 years old, less than 1% had hollows, while all > 400-year-old trees had hollows. Hollows formed at earlier ages in fast-growing trees than in slow-growing trees, which may be because hollows are formed when big branches shed, and branches are thicker on fast-growing trees in comparison to slow-growing trees of the same age. The simulation model was evaluated by predicting the frequency of presence of hollows in relation to tree size in seven oak stands in the study area. The evaluation suggested that future studies should focus on tree mortality at different conditions. Tree ring methods on individual trees are useful in studies on development of hollow trees as they allow analysis of the variability in time for hollow formation among trees. (C) 2008 Elsevier B.V. All rights reserved.
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