Genetics and ecology of natural populations Elisabeth Lundqvist Umeå 2002 Division of Genetics / Department of Molecular Biology Umeå University SE-901 87 Umeå Sweden AKADEMISK AVHANDLING Som med vederbörligt tillstånd av rektorsämbetet vid Umeå Universitet för erhållande av filosofie doktorsexamen i genetik kommer att offentligen försvaras fredagen den 27 september, kl 13.00 i sal KB3 Bl, KBC-huset Examinator: Docent Åsa Rasmuson-Lestander Opponent: Docent Ulf Lagercrantz, Inst. för växtbiologi, SLU, Uppsala Organisation Document name Umeå University DOCTORAL DISSERTATION Department of Molecular Biology / Division of Genetics SE-901 87 Umeå, Sweden Author Date of issue Elisabeth Lundqvist September 2002 Title Genetics and ecology of natural populations Abstract I have studied the genetic variation of single species using morphological variation and enzyme electrophoresis. I have striven to understand the interaction between the breeding structure and the ecology of the species in relation to the community, in which it lives. The work was done in the county of Västerbotten, northern Sweden. In the Skeppsvik archipelago I have studied the population structure of Silene dioica: ecotypic variation in other populations. I have also studied the genetic diversity of Angelica archangelica, Bistorta vivipara, Viscaria alpina and the earthworm Eiseniella tetraedra along the free-flowing Vindel and Sävar Rivers and the regulated Urne River. The island populations of S. dioica are subdivided into several breeding units and levels of differentiation among subpopulations within islands were about twice as high as among islands. Restricted seed and pollen dispersal creates patches made up of related individuals that may diverge as a result of drift. Frequent seed and pollen dispersal occurs among islands and they will receive the same alleles. This may explain the pattern of differentiation observed. In contrast, the patches within islands may be founded by only a few individuals. * S. dioica exhibits morphological differentiation in vegetative and floral characters between serpentine, cold spring, rich forest and coastal habitats. There was no association between genetic and geographical distance or between genetic distance and habitat. Serpentine and cold spring, which represented the most extreme habitats were also most differentiated. Populations of S. dioica are subject to herbivory; predation may exert a selective pressure on vegetative characters. A number of selective forces such as pollinators and fungal parasites act on reproductive characters. Assuming that water dispersal is important I tested several hypotheses to explain patterns of genetic diversity expected to be exhibited by riparian organisms along free-flowing and regulated rivers. I show that dispersal, distribution and breeding structure are important determinants of the evolution of the riparian flora. Patterns of genetic diversity may be exhibited at many spatial scales, e.g. among entire rivers, and between types of riverbanks within a river reach. Populations must be sampled at a spatial scale relevant to the hypothesis to be tested. Key words Angelica archangelica, Bistorta vivipara, Viscaria alpina,Eiseniella tetraedra, ecotypes, hydrochory, genetic differentiation, clone diversity, genetic patterns, riparian Language ISBN Number of pages English 91-7305-286-8 148 Signature Date 2002-05-27 <1 Genetics and ecology of natural populations Elisabeth Lundqvist Umeå 2002 Division of Genetics / Department of Molecular Biology Umeå University SE-901 87 Umeå Sweden AKADEMISK AVHANDLING Som med vederbörligt tillstånd av rektorsämbetet vid Umeå Universitet för erhållande av filosofie doktorsexamen i genetik kommer att offentligen försvaras fredagen den 27 september, kl 13.00 i sal KB3 Bl, KBC-huset Examinator: Docent Åsa Rasmuson-Lestander Opponent: Docent Ulf Lagercrantz, Inst. för växtbiologi, SLU, Uppsala Organisation Document name Umeå University DOCTORAL DISSERTATION Department of Molecular Biology / Division of Genetics SE-901 87 Umeå, Sweden Author Date of issue Elisabeth Lundqvist September 2002 Title Genetics and ecology of natural populations Abstract I have studied the genetic variation of single species using morphological variation and enzyme electrophoresis. I have striven to understand the interaction between the breeding structure and the ecology of the species in relation to the community, in which it lives. The work was done in the county of Västerbotten, northern Sweden. In the Skeppsvik archipelago I have studied the population structure of Silene dioica: ecotypic variation in other populations. I have also studied the genetic diversity of Angelica archangelica, Bistorta vivipara, Viscaria alpina and the earthworm Eiseniella tetraedro along the free-flowing Vindel and Sävar Rivers and the regulated Urne River. The island populations of S. dioica are subdivided into several breeding units and levels of differentiation among subpopulations within islands were about twice as high as among islands. Restricted seed and pollen dispersal creates patches made up of related individuals that may diverge as a result of drift. Frequent seed and pollen dispersal occurs among islands and they will receive the same alleles. This may explain the pattern of differentiation observed. In contrast, the patches within islands may be founded by only a few individuals. S. dioica exhibits morphological differentiation in vegetative and floral characters between serpentine, cold spring, rich forest and coastal habitats. There was no association between genetic and geographical distance or between genetic distance and habitat. Serpentine and cold spring, which represented the most extreme habitats were also most differentiated. Populations of S. dioica are subject to herbivory; predation may exert a selective pressure on vegetative characters. A number of selective forces such as pollinators and fungal parasites act on reproductive characters. Assuming that water dispersal is important I tested several hypotheses to explain patterns of genetic diversity expected to be exhibited by riparian organisms along free-flowing and regulated rivers. I show that dispersal, distribution and breeding structure are important determinants of the evolution of the riparian flora. Patterns of genetic diversity may be exhibited at many spatial scales, e.g. among entire rivers, and between types of riverbanks within a river reach. Populations must be sampled at a spatial scale relevant to the hypothesis to be tested. Key words Angelica archangelica, Bistorta vivipara, Viscaria alpina,Eiseniella tetraedro, ecotypes, hydrochory, genetic differentiation, clone diversity, genetic patterns, riparian Language ISBN Number of pages English 91-7305-286-8 148 Signature Date 2002-05-27 To my family ISBN 91-7305-286-8 © Elisabeth Lundqvist, 2002 Printed by: Solfjädern Offset AB Cover drawing by Veronica Lundqvist CONTENTS LIST OF PAPERS.................................................................................................... 1 INTRODUCTION.................................................................................................... 2 Genetic variation in natural populations ................................................... 3 Genetic structure of natural populations ................................................... 3 Genetic adaptation in natural populations................................................ 4 Human impact of natural populations ....................................................... 5 The aims of this thesis................................................................................ 7 The plants and the worm ............................................................................ 7 The populations and rivers ........................................................................ 9 SUMMARY OF THE PAPERS............................................................................. 12 Paper 1 ............................................................................................................ 12 Paper II .......................................................................................................... 12 Paper III......................................................................................................... 13 Paper IV ........................................................................................................ 14 Paper V........................................................................................................... 15 DISCUSSION........................................................................................................... 16 Genetic structure and morphology of S. dioica....................................... 16 Genetic variation and patterns in riparian corridors ............................... 18 ACKNOWLEDGEMENTS..................................................................................... 20 REFERENCES.......................................................................................................... 20 Acknowledgements.................................................................................................... 27 References.................................................................................................................. 29 LIST OF PAPERS This thesis is a summary of the following papers, which will be referred to by their Roman numerals: I. Giles, B. E., Lundqvist, E. and Goudet, J. 1998. Restricted gene flow and subpopulation differentiation in Silene dioica. Heredity,