Ivana Stehlik, Lecturer
Department of Ecology and Evolutionary Biology
University of Toronto
25 Willcocks Sreet
Toronto, Ontario, Canada
Phone: (416) 946-0007
| Lecturer, Department of Ecology and Evolutionary Biology,
University of Toronto, Toronto, Ontario, Canada
| Postdoctoral fellowship with Prof. S.C.H. Barrett Department of Ecology and Evolutionary Biology,
University of Toronto, Toronto, Ontario, Canada
| Ph.D. Thesis "Resistance or emigration: response of alpine plants to the ice ages"
| Organization of the international 'First Joint Botanical Mountain Phylogeography Meeting' in Zürich, in collaboration with the Institute of Botany, University of Vienna, Austria
| Co-organizer with Profs. Pamela and Douglas Soltis (Department of Botany, University of Florida, Gainesville, Florida, USA) of a meeting sponsored by the University of Zürich for a peer-mentoring group that aims to encourage, inform and support female scientists in their scientific career
| Visiting researcher Department of Taxonomy, Institute of Plant Genetics and Crop Plant Research, IPK, Gatersleben, Germany (head: Prof. K. Bachmann)
| Graduate research, Institute of of Botany, University of Zürich, on the phylogeography of the alpine plants Eritrichium nanum, Erinus alpinus, Rumex nivalis and Saxifraga oppositifolia
| Diploma thesis "Spatial genetic structure and clonal diversity of Anemone nemorosa in late successional deciduous woodlands of Central Europe" ("Räumlich-genetische Struktur der klonalen Art Anemone nemorosa") under the guidance of Profs. J.J. Schneller and C.D.K. Cook
| Diploma as a licensed Swiss Federal mushroom controller
| Study of biology and systematic Botany at the University of Zürich
Phylogeography of alpine plants There is a long-standing debate about the fate of the mountain flora of the European Alps during the Quaternary ice ages. Two opposing views about glacial survival of alpine plants have been proposed: the nunatak and the tabula rasa hypotheses. According to the former, species survived in situ on small 'islands in a sea of ice' (nunataks), whereas the tabula rasa (Latin for 'empty table') hypothesis assumes that species colonized vacant Alpine regions from peripheral refugia after the retreat of the glaciers. There was a first flush of investigations in this field of alpine biogeography at the beginning of the 20th century. These studies mainly relied on distribution patterns of alpine plants. Locations of glacial survival on nunataks, peripheral refugia and corresponding migration routes into the Central Alps were documented as precisely as possible at that time (Stehlik 2000). In combination with molecular methods, this background offers fascinating options to re-evaluate the questions asked by the pioneers of alpine biogeographical research and to address them with modern approaches. The aim of my research conducted in collaboration with Konrad Bachmann and Frank Blattner (Institute of Plant Genetics and Crop Plant Research, IPK, Gatersleben, Germany), Rolf Holderegger (Swiss Federal Research Institute, WSL, Birmensdorf, Switzerland), Peter Schönswetter (Institute of Botany, University of Vienna, Vienna, Austria) and Andreas Tribsch (NCB National Centre for Biosystematics, Natural History Museums and Botanical Gardens, University of Oslo, Norway) is to test explicit phylogeographic hypotheses on plant species of the European Alps with distinctly different ecological demands and distribution patterns.
Hypothesized view of the Central Alps in Switzerland (viewed from Lucerne) ~16kY BP
Evolution and consequences of dioecy in alpine Rumex nivalis My research focuses on the mechanisms governing sex-ratio variation in Rumex nivalis (Polygonaceae), a dioecious, alpine herb in which populations are strongly female-biased. Rumex nivalis has a chromosomal sex determination, in which females possess XX, and males XYY, sex chromosomes. Using field surveys and a glasshouse experiment I investigated the relation between sex ratios and life-history stage in populations from contrasting elevations and snowbed microsites in Switzerland (Stehlik and Barrett in press). A male-specific SCAR-marker enabled me to determine the gender of non-flowering individuals. Female bias in flowering portions of populations was one of the highest reported for a dioecious species, but males increased in frequency at higher elevations and in the centers of snowbeds. Female bias was also evident in non-flowering portions of populations. Open-pollinated seeds were less female-biased, with the degree of bias associated with the flowering sex ratio of populations, a result consistent with certation. Under glasshouse conditions, females suffered less mortality and outperformed males at several life history stages. Male seeds were significantly heavier than female seeds but the proportional difference was considerably smaller than their relative frequencies in seed progenies. Poor performance of male gametophytes and sporophytes in R. nivalis may be a consequence of the accumulation of deleterious mutations on Y sex chromosomes because males are the heterogametic sex.
I intend to further elucidate the role of different levels of pollination intensity. This part of my project is highly novel, as the direct chain of inference of local pollen abundance, pollen loads on female flowers, seed set and seed sex ratios has never been tested. I intend to do this in natural populations and in a pollination experiment which allows me to better control the levels of pollen availability for females. This is important as not all flowering individuals in natural populations flower at exactly the same time.
One intriguing finding is the difference in seed weight between female and male seeds in natural populations. Therefore I intend to investigate whether seed weight differences persist in seeds produced under glasshouse conditions supporting a genetic cause for this sexual dimorphism. Sex-differential seed weight has hitherto never been observed (although it has been searched for) in dioecious species with sex chromosomes.
The average natural seed sex ratio was much less female-biased than the average sex ratio of natural populations. In an assessment of mortality under glasshouse conditions and over a period of approximately one year, females suffered significantly less mortality than males, however, the difference of 6% more male deaths was relative small and does not adequately explain the strong discrepancy between seed and adult sex ratios. I therefore intend to mimic more appropriately natural stress acting on natural populations and monitor sex-specific survival rates in further experiments.
I aim at further investigating possible causes of the exceptionally high level of female bias in seed progenies of R. nivalis. It has been shown that meiotic drive can cause the abortion of one class of gametes, and, as shown in organisms with meiotic drive, of mostly male-determining gametes. I intend to test this by assessing the pollen sizes using the Elzone particle counter to examine whether viability differerences associated with aborted or maladaptive pollen size variation occurs.
Rumex nivalis (Polygonaceae)
Influences of stigma-height dimorphism in Narcissus species An unusual stylar dimorphism occurs in Narcissus, a Mediterranean insect-pollinated genus. In long-styled morphs (L-morph), the stigma is located within or slightly above the upper-level stamens, whereas in short-styled plants (S-morph), the stigma is placed below the lower-level stamens. The mean stigma-anther separation is much greater in the S-morph than the L-morph. In populations of N. assoanus, style-morph ratios vary from isoplethy (1L:1S) to L-biased and ratios are associated with population size: large continuous populations exhibit isoplethic ratios, whereas smaller, fragmented populations are often L-morph biased. Using microsatellite markers and paternity analysis, I will test whether these style-morph ratios largely result from morph-specific differences in assortative mating.
- Holderegger R., Landolt E., Stehlik I., Urmi E. and Wohlgemuth Th. 1996. Ist die Reliktflora der Fallätsche gefährdet? Floren- und Vegetationsveränderung in einem Erosionstrichter bei Zürich. Bot. Helv. 106: 209-225.
- Holderegger R., Stehlik I. and Schneller J.J. 1998. Estimation of relative importance of sexual and vegetative reproduction in the clonal woodland herb Anemone nemorosa. Oecologia 117: 105-107. pdf
- Holderegger R. and Stehlik I. 1999. Sibmating in a small, isolated population of the dioecious plant species Mercurialis ovata. Biochem. Syst. Ecol. 27: 681-685. pdf
- Stehlik I. and Holderegger R. 2000. Spatial genetic structure and clonal diversity of Anemone nemorosa in late successional deciduous woodlands of Central Europe. J. Ecol. 88: 424-435. pdf
- Stehlik I. 2000. Nunataks and peripheral refugia for alpine plants during quaternary glaciation in the middle part of the Alps. Bot. Helv. 110: 25-30.
- Stehlik I., Holderegger R., Schneller J.J., Abbott R.J. and Bachmann K. 2000. Molecular biogeography and population genetics of alpine plant species. Bull. Geobot. Inst. ETH 66: 47-59.
- Stehlik I., Schneller J.J. and Bachmann K. 2001. Resistance or emigration: response of the high-alpine plant Eritrichium nanum (L.) Gaudin to the ice age within the Central Alps. Mol. Ecol. 10: 357-370. pdf
- Stehlik I., Tribsch A. and Schönswetter P. 2001. First Joint Botanical Mountain Phylogeography Meeting. Bauhinia 15: 69-90. pdf
- Stehlik I., Schneller J.J. and Bachmann K. 2002. Immigration and in situ glacial survival of the low-alpine Erinus alpinus (Scrophulariaceae). Biol. J. Linn. Soc. 77: 87-103. pdf
- Stehlik I., Blattner F.R., Holderegger R. and Bachmann K. 2002. Nunatak survival of the high alpine plant Eritrichium nanum (L.) Gaudin in the Central Alps during the Ice Ages. Mol. Ecol. 11: 2027-2036. pdf
- Holderegger R., Stehlik I. and Abbott R.J. 2002. Molecular analysis of the Pleistocene history of Saxifraga oppositifolia in the Alps. Mol. Ecol. 11: 1409-1418. pdf
- Stehlik I. 2002. Glacial history of the alpine Rumex nivalis (Polygonaceae): a comparison of common phylogeographic methods with nested clade analysis. Amer. J. Bot. 89: 2007-2016 pdf
- Stehlik I. 2003. Resistance or emigration? Response of alpine plants to the ice ages. Taxon 52: 499-510 pdf
- Holderegger R., Stehlik I., Smith R.I.L. and Abbott R.J. 2003. Populations of Antarctic hairgrass (Deschampsia antarctica) show low genetic diversity. Arct. Antarct. Alp. Res. 35: 2144-217 pdf
- Jorgensen J.L., Stehlik I., Brochmann C. and Conti E. 2003. Implications of ITS sequences and rapd markers foe the taxonomy and biogeograpgy of the taxonomically disputed Oxytropis campestris and O. arctica complexes. Amer. J. Bot. 50: 1470-1480 pdf
- Schönswetter P., Tribsch A., Stehlik I. and Niklfeld H. 2004. History of high alpine Ranunculus glacialis (Ranunculaceae) in the European Alps in a comparative phylogeographical context. Biol. J. Linn. Soc. 81: 183-195 pdf
- Stehlik I. and Blattner F.R. 2004. Sex-specific SCAR markers in the dioecious plant Rumex nivalis (Polygonaceae) and implications for the evolution of sex chromosomes. Theor. Appl. Genet. 108: 238-242 pdf
- Stehlik I. and Barrett SCHB 2005. Mechanims governing sex-ratio variation in dioecious Rumex nivalis (Polygonaceae) Evolution in press
1998 At the contest of the ICAS meeting (Interacademic Commission for Alpine Science) for diploma and PhD students, Fribourg, Switzerland
1999 Invited: at the Institute of Plant Sciences, Bern, Switzerland
2000 Invited: at the Institute of Botany and Botanical Garden of the University of Vienna, Austria; at the annual botanical congress of the American Botanical Society (ABS), Portland, Oregon, US
2001 Invited: at the Botanical Institute of the University of Basel, Switzerland; at the annual 'Zoologia et Botanica' meeting, Neuchâtel, Switzerland; at the 'First Joint Botanical Mountain Phylogeography Meeting', Zurich, Switzerland; at the Evolution 2001 congress, Knoxville, Tennessee, US; invited: at the Botanical Institute of the University of Neuchâtel, Switzerland
2002 Invited: at the Institute of Plant Genetics and Crop Plant Research, IPK, Gatersleben, Germany; Invited: at the ICSEB VI Congress, Biodiversity in the Information Age, Patras, Greece
2003 Invited: at the Dept. of Biology, Queen's University, Kingston, Ontario, Canada
2004 Invited: Institute of Botany, University of Munich, Munich, Germany; Invited: Federal Technical Highschool ETH, D-UWIS, the Department of Environmental Sciences, Zuerich, Switzerland; Invited: Swiss Federal Research Institute WSL, Birmensdorf, Switzerland; Evolution 2004 Congress, Fort Collins, Colorado, US
2005 International Botanical Congress, Vienna, Austria
2002 At the annual meeting of the American Botanical Society (ABS), Portland, Oregon, USA
2001 At the annual 'Zoologia et Botanica' meeting, Neuchâtel, Switzerland
Nine published abstracts
1998 For the diploma thesis "Räumlich-genetische Struktur der klonalen Art Anemone nemorosa", by the Faculty of Mathematics and Science of the University of Zurich, Switzerland
2000 For the best presentation in the section 'PhD-students' at the contest of the ICAS meeting (Interacademic Commission for Alpine Studies), Fribourg, Switzerland
2002 For the PhD thesis "Resistance or emigration? Response of alpine plants to the ice ages", by the Faculty of Mathematics and Science of the University of Zurich, Switzerland
Grants and financial support
1998 5,000 SFr. for "Resistance or emigration: response of alpine plants to the ice ages": by the Swiss Alpine Club (SAC).
2,000 SFr. by the 'Georges-and-Antoine-Claraz-Foundation';
125,000 SFr. to J.J. Schneller and I. Stehlik, by the Swiss National Science Foundation SNF, for "Resistance or emigration: response of alpine plants to the ice ages"
2001 For the organization of the 'First Joint Botanical Mountain Phylogeography Meeting', Zurich, Switzerland: 500 SFr. by the 'Zürcherische Botanische Gesellschaft', 500 SFr. by the 'Swiss Academy of Science' SANW, 1,000 SFr. by the city of Zurich
2002 5,000 SFr. for the development of sex-specific primers in the dioecous Rumex nivalis, by the Interacademic Commission for Alpine Studies (ICAS)
2005 20,000 SFr. for 'Mechanims governing sex-ratio variation in dioecious Rumex nivalis' by the Swiss National Science Foundation SNF
1993, 1994 Organization of field weeks for students of biology of University of Zurich in the Alps
1996-2002 Assistence in numerous and different courses at the Institute of Systematic Botany of the University of Zurich (e.g. plant morphology, molecular genetics)
2003 Lecturer in the undergarduate course 'Plants and Society: Plant domestication and improvment at the University of Tortonto (12 lectures)
Activity as a field guide in botanical excursions
Alpine, Arctic & Antarctic Research (1)
Botanica Helvetica (2)
Conservation Biology (1)
International Journal of Plant Science (1)
Molecular Ecology (5)
Plant Systematics and Evolution (2)
Further field experience
1995-2002 Leading 36 botanical excursions for the Institute of Systematic Botany of the University of Zurich covering all the different regions of Switzerland
1997 Botanical excursion for the Botanical Society of Zurich (ZBG), Switzerland
1999 Mycological excursion for the Botanical Society of Zurich (ZBG), Switzerland
1999-2002 Four excursions for different nature protection associations, Switzerland
1996 Kreta, Greece
1997 Estremadura, Spain
1998 Teneriffa, Canaric Islands, Spain
2000 Eastern Alps, Italy
2002 Georgia, Caucasus; Cape region, South Africa
Swiss Botanical Society, Switzerland
Botanical Society of Zurich, Switzerland
Mycological Society of Zurich, Switzerland
Botanical Society of America, USA
EEB Home Page | Barrett
Lab Home Page | Top of this page