Within and Between Plant Variation in Seed Number, Seed Mass and Germinability of Primula elatior: Effect of Population Size

Abstract

In this study, natural variation of seed mass and seed number between and within individual plants of P. elatior, a common forest herb on rich soils in Flanders, was investigated for both small (< 50 flowering individuals) and large (> 1000 flowering individuals) populations. The relationship between seed number and seed mass at both the between and within population level was also quantified. We also investigated how population size affected germinability of seeds through the effects of seed mass. Seed number varied by a factor of twenty, whereas seed mass spanned, on average, a 3.5 range. In both cases variation was highest among populations, indicating that population size has important effects on seed number and seed mass. Next, seed number-seed mass tradeoffs were significantly influenced by population size, with small populations showing strong negative relationships whereas in large populations seed mass was only marginally influenced by seed number. As to germination, larger seeds showed larger germination percentages only for the smallest population. In all other populations, seed mass had little effect on germination.

Key words

dimorphic species - pin-thrum ratio - pollinator limitation - seed production

References

• 01 Ågren,  J.. (1996);  Population size, pollinator limitation, and seed set in the self-incompatible herb Lythrum salicaria. .  Ecology. 77 1779-1790
• 02 Boyd,  M.,, Silverton,  J.,, and Tucker,  C.. (1990);  Population ecology of heterostyle and homostyle Primula vulgaris: growth, survival and reproduction in field populations.  Journal of Ecology. 78 799-813
• 03 Byers,  D. L.. (1995);  Pollen quantity and quality as explanations for low seed set in small populations exemplified by Eupatorium (Asteraceae).  American Journal of Botany. 82 1000-1006
• 04 de Jong,  T. J., and Klinkhamer,  P. G. L.. (1989);  Limiting factors for seed production in Cynoglossum officinale. .  Oecologia. 80 167-171
• 05 DeMauro,  M. M.. (1993);  Relationship of breeding system to rarity in the lakeside daisy (Hymenoxys acaulis var. glabra).  Conservation Biology. 7 542-550
• 06 Dierschke,  H.. (1968);  Zur synsystematischen und syndynamischen Stellung einiger Calthion-Wiesen mit Ranunculus auricomus L. und Primula elatior (L.) Hill im Wümme-Gebiet.  Mitteilungen der Floristisch-soziologischen Arbeitsgemeinschaft, Neue Fassung. 13 59-70
• 07 Dirzo,  R., and Dominguez,  C. A.. (1986) Seed shadows, seed predation and the advantages of dispersal. Frugivores and seed dispersal. Estrada, A. and Fleming, T., eds. Dordrecht; Junk pp. 237-250
• 08 Eisto,  A.,, Kuitunen,  M.,, Lammi,  A.,, Saari,  V.,, Suhonen,  J.,, Syrjäsuo,  S.,, and Tikka,  P. M.. (2000);  Population persistence and offspring fitness in the rare bellflower Campanula cervicaria in relation to population size and habitat characteristics.  Conservation Biology. 14 1413-1421
• 09 Fischer,  M., and Matthies,  D.. (1998);  The effect of population size on performance in the rare plant Gentianella germanica. .  Journal of Ecology. 86 195-204
• 10 Haig,  D., and Westoby,  M.. (1988) Inclusive fitness, seed resources, and maternal care. Plant reproductive ecology: patterns and strategies. Lovett Doust, D. and Lovett Doust, L., eds. New York; Oxford University Press pp. 60-79
• 11 Harper,  J. L.. (1977) Population biology of plants. London; Academic Press
• 12 Harper,  J. L.,, Lovell,  P. H.,, and Moore,  K. G.. (1970);  The shapes and sizes of seeds.  Annu. Rev. Ecol. Syst.. 1 256-327
• 13 Hendrix,  S. D.. (1984);  Variation in seed weight and its effects on germination in Pastinaca sativa L. (Umbelliferae).  American Journal of Botany. 71 795-802
• 14 Heschel,  M. S., and Paige,  K. N.. (1995);  Inbreeding depression, environmental stress, and population size variation in Scarlet Gilia (Ipomopsis aggregata). .  Conservation Biology. 9 126-133
• 15 Jacobsson,  A., and Eriksson,  O.. (2000);  A comparative study of seed number, seed size, seedling size and recruitment in grassland plants.  Oikos. 88 494-502
• 16 Jennersten,  O.. (1988);  Pollination in Dianthus deltoides (Caryophyllaceae): effects of habitat fragmentation on visitation and seed set.  Conservation Biology. 2 359-366
• 17 Kéry,  M.,, Matthies,  D.,, and Spillmann,  H.. (2000);  Reduced fecundity and offspring performance in small populations of the declining grassland plants Primula veris and Gentiana lutea. .  Journal of Ecology. 88 17-30
• 18 Kwak,  M. M.,, Velterop,  O.,, and van Andel,  J.. (1998);  Pollen and gene flow in fragmented habitats.  Applied Vegetation Science. 1 37-54
• 19 Lee,  T. D.. (1988) Patterns of fruit and seed production. Plant reproductive ecology: patterns and strategies. Lovett Doust, D. and Lovett Doust, L., eds. New York; Oxford University Press pp. 60-79
• 20 Lee,  T. D., and Bazzaz,  F. A.. (1982);  Regulation of fruit maturation pattern in an annual legume, Cassia fasciculata. .  Ecology. 63 1374-1388
• 21 Les,  D. H.,, Reinartz,  J. A.,, and Esselman,  E. J.. (1991);  Genetic consequences of rarity in Aster furcatus (Asteraceae), a threatened, self-incompatible plant.  Evolution. 45 1641-1650
• 22 Lloyd,  D. G.. (1987);  Selection of offspring size at independence and other size-versus-number strategies.  American Naturalist. 130 370-398
• 23 Mazer,  S. J.. (1987);  The quantitative genetics of life history and fitness components in Rahpanus raphanistrum L. (Brassicaceae): ecological and evolutionary consequences of seed-weight variation.  American Naturalist. 130 891-914
• 24 McGinley,  M. A.,, Temme,  D. H.,, and Geber,  M.. (1987);  Parental investment in offspring in variable environments: theoretical and empirical considerations.  American Naturalist. 130 370-398
• 25 Menges,  E. S.. (1991);  Seed germination increases with population size in a fragmented prairie species.  Conservation Biology. 5 158-164
• 26 Morgan,  J. W.. (1999);  Effects of population size on seed production and germinability in an endangered, fragmented grassland plant.  Conservation Biology. 13 266-273
• 27 Piper,  J.,, Charlesworth,  B.,, and Charlesworth,  D.. (1986);  Breeding system evolution in Primula vulgaris and the role of reproductive assurance.  Heredity. 56 201-217
• 28 Oostermeijer,  J. G. B.,, van Eijck,  M. W.,, and den Nijs,  J. C. M.. (1994);  Offspring fitness in relation to population size and genetic variation in the rare perennial plant species Gentiana pneumonanthe (Gentianaceae).  Oecologia. 97 289-296
• 29 Oostermeijer,  J. G. B.,, Brugmann,  M. L.,, de Boer,  E. R.,, and den Nijs,  J. C. M.. (1996);  Temporal and spatial variation in the demography of Gentiana pneumonanthe, a rare perennial herb.  Journal of Ecology. 84 153-166
• 30 Ouborg,  N. J., and van Treuren,  R.. (1995);  Variation in fitness-related characters among small and large populations of Salivia pratensis. .  Journal of Ecology. 83 369-380
• 31 Richards,  A. J.. (1997) Plant Breeding Systems. London; Chapman and Hall
• 32 Roff,  D. A.. (1992) The evolution of life histories: theory and analysis. New York, NY; Chapman and Hall
• 33 Salisbury,  E. J.. (1942) The reproductive capacity of plants. London; Bell and Sons
• 34 Smith,  C. C., and Fretwell,  S. D.. (1974);  The optimal balance between size and number of offspring.  American Naturalist. 108 499-506
• 35 Snow,  A. A.. (1982);  Pollination intensity and potential seed set in Passiflora vitifolia. .  Oecologia. 55 231-237
• 36 Stöcklin,  J., and Favre,  P.. (1994);  Effects of plant size and morphological constraints on variation in reproductive components in two related species of Epilobium. .  Journal of Ecology. 82 735-746
• 37 Thomson,  J. N.. (1984);  Variation among individual seed masses in Lomatium grayi (Umbelliferae) under controlled conditions: magnitude and partitioning of the variance.  Ecology. 65 626-631
• 38 Valentine,  D. H.. (1948);  Studies in British Primulas - II. Ecology and taxonomy of primrose and oxlip (Primula vulgaris Huds. and P. elatior Schreb.).  New Phytologist. 47 111-130
• 39 Vaughton,  G., and Ramsey,  M.. (1997);  Seed mass variation in the shrub Banksia spinulosa (Proteaceae): resource constraints and pollen source effects.  International Journal of Plant Sciences. 158 424-431
• 40 Vaughton,  G., and Ramsey,  M.. (1998);  Sources and consequences of seed mass variation in Banksia marginata (Proteaceae).  Journal of Ecology. 86 563-573
• 41 Werner,  P. A., and Platt,  W. J.. (1976);  Ecological relationship of co-occuring goldenrods (Solidago: Compositae).  American Naturalist. 140 287-304
• 42 Westoby,  M.,, Leishman,  M.,, and Lord,  J.. (1996);  Comparative ecology of seed size.  Phil. Trans. R. Soc. London. B 351 1309-1318
• 43 Whale,  D. M.. (1983);  The response of Primula species to soil waterlogging and soil drought.  Oecologia. 58 272-277
• 44 Willson,  M. F.. (1993);  Dispersal mode, seed shadows, and colonization patterns.  Vegetatio. 107/108 261-280
• 45 Winn,  A. A.. (1991);  Proximate and ultimate sources of variation of within-individual variation in seed mass in Prunella vulgaris (Lamiaceae).  American Journal of Botany. 78 838-844
• 46 Winn,  A. A., and Werner,  P. A.. (1987);  Regulation in seed yield within and among populations of Prunella vulgaris. .  Ecology. 68 1224-1233
• 47 Wolf,  L. L.,, Hainsworth,  F. R.,, Mercier,  T.,, and Benjamin,  R.. (1986);  Seed size variation and pollination uncertainty in Ipomopsis aggregata (Polemoniaceae).  Journal of Ecology. 74 99-111
• 48 Wulff,  R. D.. (1986);  Seed size variation in Desmodium paniculatum. I. Factors affecting seed size.  Journal of Ecology. 74 87-97

Section Editor: R. Aerts