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Christoph Reisch:

Climatic oscillations and the fragmentation of plant populations - genetic diversity within and among populations of the glacial relict plants Saxifraga paniculata (Saxifragaceae) and Sesleria albicans (Poaceae)

2002. VII, 113 pages, 15 figures, 26 tables, 14x23cm, 270 g
Language: English

(Dissertationes Botanicae, Band 359)

ISBN 978-3-443-64271-6, paperback, price: 36.00 €

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Keywords

botany glacial plant axifraga paniculata Saxifragaceae Sesleria albicans Poaceae

Contents

Abstract top ↑

Saxifraga paniculata and Sesleria albicans are glacial relict plants. The present distribution of the two species is a result of the climatic changes after the last glaciation. Population size and range of Saxifraga and Sesleria were greatly reduced since the end of the pleistocene.

Populations of Saxifraga and Sesleria were fragmented at least since the end of the last glaciation. Furthermore, the relict populations colonize habitats, which differ from each other with regard to ecological conditions. In the present investigation this was used to study the consequences of longterm isolation for the genetic diversity of plant populations and to analyze the genetic differentiation of populations and the development of ecotypes.

The results clearly showed a high level of geographic differentiation among populations of Saxifraga paniculata and a significant correlation of the genetic distance and the geographic distance between the populations. In contrast, Sesleria albicans exhibited only a low level of geographic differentiation. A significant correlation of the genetic distance and the geographic distance could not be observed. Both S. paniculata and S. albicans exhibited considerable levels of genetic diversity within populations. However, genetic diversity was slightly higher within populations of Sesleria. Furthermore, genetic variability highly significant correlated with population size in both species. Peripheral relict populations of both species were genetically less variable than the populations from the present main distribution area in the Alps.

Mutualities and differences between the two species can be explained by the history of the populations, the pollination system and distribution of the species. The results of this thesis show the significance of population genetic data for the formulation of appropriate management strategies.

Contents top ↑

1 Genetic diversity within and among populations of glacial relicts -
a general introduction. 1
1.1 Origin and distribution of glacial relict plant populations 1
1.2 Population genetics of rare glacial relict plants 1
1.3 Population genetics and the fragmentation of populations. 4
1.4 Population genetics and the differentiation of populations. 5
1.5 Methods for the measurement of genetic diversity. 6
1.6 Aim of the investigation 8
1.7 References. 9
2 Genetic diversity within and among populations of the rare glacial
relict plant Saxifraga paniculata Mill. (Saxifragaceae) in central
Europe. 14
2.1 Introduction. 14
2.2 Material and methods 17
2.2.1 Species description 17
2.2.2 Study sites. 17
2.2.3 Plant material and sampling conditions 18
2.2.4 Population size and plant communities. 20
2.2.5 DNA isolation. 22
2.2.6 RAPD analysis 22
2.2.6.1 DNA amplification 22
2.2.6.2 Data scoring 23
2.2.6.3 Statistical analysis. 23
2.2.7 ITS analysis. 24
2.3 Results. 25
2.3.1 RAPD banding 25
2.3.2 AMOVA analysis and variance partitioning. 26
2.3.3 Genetic distances (( ST) and gene flow among populations. 27
2.3.4 Genetic diversity within populations 28
2.3.5 Genetic diversity within populations from different geographic
regions 29
2.3.6 Molecular variance and population size 30
2.3.7 Population clustering. 32
2.3.8 Subpopulation clustering. 32
2.3.9 Genetic diversity among nearest neighbour plants. 34
2.3.10 ITS analysis. 36
2.4 Discussion. 37
2.4.1 Partitioning of molecular variance within and among populations 37
2.4.2 Levels of genetic diversity within relict populations 39
2.4.2.1 Effects of population size 40
2.4.2.2 Effects of mating system. 41
2.4.2.3 Effects of longevity and clonality. 42
2.4.3 Genetic diversity in central and peripheral populations 42
2.5 References. 44
3 Genetic diversity within and among populations of the glacial relict
plant Sesleria albicans Kit. ex Schultes (Poaceae) from different
habitats in central Europe 52
3.1 Introduction. 52
3.2 Material and methods 55
3.2.1 Species description 55
3.2.2 Study sites. 56
3.2.3 Plant material and sampling conditions 57
3.2.4 Population size and plant communities. 57
3.2.5 DNA isolation. 61
3.2.6 RAPD analysis 61
3.2.6.1 DNA amplification 61
3.2.6.2 Data scoring 62
3.2.6.3 Statistical analysis. 62
3.3 Results. 63
3.3.1 RAPD banding 63
3.3.2 AMOVA analysis and variance partitioning. 64
3.3.3 Genetic distances (( ST) and geneflow among populations. 66
3.3.4 Genetic diversity within populations 68
3.3.5 Genetic diversity within populations from different habitats and
regions. 69
3.3.6 Molecular variance and population size 70
3.3.7 Population clustering. 73
3.4 Discussion. 76
3.4.1 Partitioning of molecular variance within and among relict
populations. 76
3.4.2 Levels of genetic diversity within relict populations 77
3.4.2.1 Effects of population size 78
3.4.2.2 Effects of longevity and clonality. 79
3.4.2.3 Effects of the ecological amplitude. 79
3.4.3 Genetic diversity in central and peripheral populations 80
3.4.4 Genetic differentiation among populations from different
habitats. 80
3.4.5 Levels of genetic diversity within populations from different
habitats 82
3.4.6 Genetic relationship between Sesleria albicans and Sesleria
caerulea. 82
3.5 References. 83
4 Genetic diversity within and among populations of Saxifraga
paniculata Mill. and Sesleria albicans Kit. ex Schultes - a comparison
of two glacial relict plants. 91
4.1 Historical events and biological traits. 91
4.2 Partitioning of molecular variance and geographical clustering 92
4.3 Genetic diversity within populations of glacial relicts 94
4.4 Genetic diversity in central populations and peripheral relict
populations 96
4.5 Conclusions with respect to the conservation of glacial relict
plants. 98
4.6 Biological traits and genetic diversity of further glacial relict
plants. 99
4.7 Prospects. 101
4.8 References. 102
5 Summary 106
6 Appendix 108