Abstract
Gentianella germanica (Willd.) Börner, a rare plant species, occurs at the margin of its distribution area in the Netherlands. It is found only in isolated patches of chalk grassland surrounded by intensively-used agricultural land. In 1997 and 1998, we investigated the spatial and temporal separation of anthers and stigma in relation to autofertility. We performed our experiments in one large and two small populations to investigate the possible selection against herkogamy and for increased autofertility in marginal populations with pollination limitation. Dichogamy appeared to be very weak and varied within individuals. Homogamous and protandrous flowers were most frequent. Dichogamy is apparently no effective barrier against self-fertilization in this species. Herkogamy varied significantly between individuals and between populations, and plant and flower size were not correlated with anther-stigma separation. Both observations suggest a genetic basis for herkogamy. Autofertility was generally high in all three populations. Only in one small population was a correlation between autofertility and herkogamy found. In this population, most plants had the stigma positioned above the anthers (mean herkogamy +0.8 mm), while in the other two populations the stigma was positioned mainly in between or below the anthers (mean herkogamy −0.55 mm). In comparison with earlier data from 1991 and 1992, plants in the large population were less herkogamous and more self-fertile in 1998. Since 1993 this population was mown each year one month earlier than usual, leading to dramatic reductions (bottlenecks) in population size. In addition, the early mowing time may have caused a further reduction of the already scarce visitation by pollinating insects. We hypothesize that both adverse conditions may have caused a selection of plants with smaller anther-stigma separation and higher autofertility and thus showing that human influence can have profound effects on the reproductive success and evolution of rare plant species, even if it occurs in the context of nature conservation.
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References
Baker H.G. &Hurd P.D. (1968): Intrafloral ecology.Annual Rev. Entomol. 13: 385–414.
Baker J.D. &Cruden R.W. (1991): Thrips-mediated self-pollination of two facultative xenogamous wetland species.Amer. J. Bot. 78: 959–963.
Barrett S.C.H. &Eckert C.G. (1990): Variation and evolution of mating systems in seed plants. In:Kawano S. (ed.),Biological approaches and evolutionary trends in plants, Academic Press, Tokyo, pp. 229–254.
Belaoussoff S. &Shore J.S. (1995): Floral correlates and fitness consequences of mating-system variation inTurnera ulmifolia.Evolution 49: 545–556.
Bertin R.I. &Newman C.M. (1993): Dichogamy in angiosperms.Bot. Rev. 59: 112–152.
Brunet J. &Eckert C.G. (1998): Effects of floral morphology and display on outcrossing in Blue Columbine,Aquilegia caerulea (Ranunculaceae).Funct. Ecol. 12: 596–606.
Carr D.E. &Fenster C.B. (1994): Levels of genetic variation and covariation forMimulus (Scrophulariaceae) floral traits.Heredity 72: 606–618.
Charlesworth D. &Charlesworth B. (1987): Inbreeding depression and its evolutionary consequences.Annual Rev. Ecol. Syst. 18: 237–268.
Dole J.A. (1992): Reproductive assurance mechanisms in three taxa of theMimulus guttatus complex (Scrophulariaceae).Amer. J. Bot. 79: 650–659.
Ennos R.A. (1981): Quantitative study of the mating system in two sympatric species ofIpomoea (Convolvulaceae).Genetica 57: 93–98.
Faegri K. &van der Pijl L. (1979):The principles of pollination ecology. Pergamon Press, New York.
Fischer M. &Matthies D. (1997): Mating structure, inbreeding depression and outbreeding depression in the rare plantGentianella germanica (Gentianaceae).Amer. J. Bot. 82: 1685–1692.
Fischer M. &Matthies D. (1998a): Experimental demography of the rareGentianella germanica: seed bank formation and microsite effects on seedling establishment.Ecography 21: 269–278.
Fischer M. &Matthies D. (1998b): RAPD variation in relation to population size and plant fitness in the rareGentianella germanica (Gentianaceae).Amer. J. Bot. 86: 811–819.
Gugerli F. (1997): Sexual reproduction inSaxifraga oppositifolia L. andSaxifraga biflora All. (Saxifragaceae) in the Alps.Int. J. Pl. Sci. 158: 274–281.
Holtsford T.P. &Ellstrand N.C. (1992): Genetic and environmental variation in floral traits affecting outcrossing rate inClarkia tembloriensis (Onagraceae).Evolution 46: 216–225.
Jennersten O. (1988): Pollination inDianthus deltoides (Caryophyllaceae): Effects of habitat fragmentation on visitation and seed set.Conservation Biol. 2: 359–366.
Karron J.D., Jackson R.T., Thumser N.N. &Schlicht S.L. (1997): Outcrossing rates of individualMimulus rigens genets are correlated with anther-stigma separation.Heredity 79: 365–370.
Kerner von Marilaun A. (1891):Pflanzenleben, Bibliographisches Institut, Leipzig, Wien.
Kirchner O. (1888):Flora von Stuttgart und Umgebung (Ludwigsburg, Waiblingen, Esslingen, Nürtingen, Leonberg, ein Teil des Schönbuches) mit besonderer Berücksichtigung der pflanzenbiologischen Verhältnisse. Eugen Umer, Stuttgart.
Kwak M.M. (1988): Pollination ecology and seed set in the rare annual speciesMelampyrum arvense L. (Scrophulariaceae).Acta Bot. Neerl. 37: 153–163.
Kwak M.M., van der Brand C., Kremer P. &Boerrigter E.J.M. (1991): Visitation, flight distances and seed set in populations of the rare speciesPhyteuma nigrum (Campanulaceae).Acta Hort. 288: 303–307.
Lande R. &Schemske D.W. (1985): The evolution of self-fertilization and inbreeding depression in plants. I. Genetic models.Evolution 39: 24–40.
Lennartsson T. (1997):Demography, reproductive biology and adaptive traits in Gentianella campestrisand G. amarella. PhD. Thesis, Swedish University of Agricultural Sciences, Uppsala.
Lloyd D.G. &Webb C.J. (1986): The avoidance of interference between the presentation of pollen and stigmas in angiosperms.New Zealand J. Bot. 24: 135–162.
Lloyd D.G. (1992): Self- and cross-fertilization in plants. II. The selection of selfing.Int. J. Pl. Sci. 153: 370–380.
Luijten S.H., Oostermeijer J.G.B., Ellis-Adam A.C. &den Nijs J.C.M. (1998): Reproductive biology of the rare biennialGentianella germanica compared with other gentians of different life history.Acta Bot. Neerl. 47: 325–336.
Meusel H., Jäger E., Rauschert S. &Weinert E. (1978):Vergleichende Chorologie der Zentral-europäischen Flora 2. Fischer Verlag, Jena.
Müller H. (1881):Alpenblumen, ihre Befruchtung durch Insekten und ihre Anpassungen an dieselben. Wilhelm Engelmann, Leipzig.
Oostermeijer J.G.B., Luijten S.H., Krenova Z.V. &den Nijs J.C.M. (1998): Relations between population and habitat characteristics and reproduction of the rareGentiana pneumonanthe L.Conservation Biol. 12: 1042–1053.
Ricca L. (1871): Osservazioni sulla fecondazione incrociata dei vegetali alpini e subalpini fatte nelle Alpi della somma Val Camonica (1871) (Observations on cross fertility of alpine and subalpine plants carried out in the mountains of the Vall Carmonica in 1871).Atti Soc. Ital. Sci. Nat. 13: 254–263.
Robertson A.W. &Lloyd G.D. (1991): Herkogamy, dichogamy and self-pollination in six species ofMyosotis (Boraginaceae).Evol. Trends Pl. 5: 53–63.
Robertson A.W., Diaz A. &Macnair M.R. (1994): The quantitative genetics of floral characters inMimulus guttatus.Heredity 72: 300–311.
Schultz A. (1888): Bestäubungseinrichtungen und Geslechtsverteilung bei den Pflanzen.Biblioth. Bot. 10: 1–103.
Schultz A. (1890): Bestäubungseinrichtungen und Geslechtsverteilung bei den Pflanzen.Biblioth. Bot. 17: 193.
Sokal R.R. &Rohlf F.J. (1981):Biometry: the principles and practice of statistics in biological research. W.H. Freeman, San Francisco.
Totland O. (1997): Limitations on reproduction in alpineRanunculus acris.Canad. J. Bot. 75: 137–144.
Verkaar H.J. &Schenkeveld A.J. (1984): On the ecology of short-lived forbs in chalk grasslands: life-history characteristics.New Phytol. 98: 659–672.
Wagner J. &Mitterhofer E. (1998): Phenology, seed development, and reproductive success of an alpine population ofGentianella germanica in climatically varying years.Bot. Acta 111: 159–166.
Webb C.J. &Lloyd D.G. (1986): The avoidance of interference between the presentation of pollen and stigmas in angiosperms II. Herkogamy.New Zealand J. Bot. 24: 163–178.
Wilkinson L. (1989):SYSTAT: the system for statistics, Version 5.2, Systat Inc., Evanston.
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Luijten, S.H., Oostermeijer, J.G.B., Ellis-Adam, A.C. et al. Variable herkogamy and autofertility in marginal populations ofGentianella germanica in the Netherlands. Folia Geobot 34, 483–496 (1999). https://doi.org/10.1007/BF02914924
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DOI: https://doi.org/10.1007/BF02914924