BACKGROUND AND AIMS: It is well known that genome size differs among species. However, information on the variation and dynamics of genome size in wild populations and on the early phase of genome size divergence between taxa is currently lacking. Genome size dynamics, heritability and phenotype effects are analysed here in a wild population of Festuca pallens (Poaceae). METHODS: Genome size was measured using flow cytometry with DAPI dye in 562 seedlings from 17 maternal plants varying in genome size. The repeatability of genome size measurements was verified at different seasons through the use of different standards and with propidium iodide dye; the range of variation observed was tested via analysis of double-peaks. Additionally, chromosome counts were made in selected seedlings. KEY RESULTS AND CONCLUSIONS: Analysis of double-peaks showed that genome size varied up to 1.188-fold within all 562 seedlings, 1.119-fold within the progeny of a single maternal plant and 1.117-fold in seedlings from grains of a single inflorescence. Generally, genome sizes of seedlings and their mothers were highly correlated. However, in maternal plants with both larger and smaller genomes, genome sizes of seedlings were shifted towards the population median. This was probably due to the frequency of available paternal genomes (pollen grains) in the population. There was a stabilizing selection on genome size during the development of seedlings into adults, which may be important for stabilizing genome size within species. Furthermore, a positive correlation was found between genome size and the development rate of seedlings. A larger genome may therefore provide a competitive advantage, perhaps explaining the higher proportion of plants with larger genomes in the population studied. The reason for the observed variation may be the recent induction of genome size variation, e.g. by activity of retrotransposons, which may be preserved in the long term by the segregation of homeologous chromosomes of different sizes during gametogenesis.

Masaryk University Faculty of Science Department of Botany and Zoology Kotlárska 2 CZ 611 37 Brno Czech Republic

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Auquier P. Biology and reproduction of Festuca L. (Poaceae): 1. pollination systems (In French) Bulletin du Jardin botanique national de Belgique. 1977;110:129–150.

Bennett MD. Duration of meiosis. Proceedings of the Royal Society of London, series B. 1971;178:277–299.

Bennett MD, Leitch IL. Plant DNA C-value Database. 2005. http://data.kew.org/cvalues/homepage.html .

Bennetzen JL. Mechanisms and rates of genome expansion and contraction in flowering plants. Genetica. 2002;115:29–36. PubMed

Bennetzen JL, Ma J, Devos KM. Mechanisms of recent genome size variation in flowering plants. Annals of Botany. 2005;95:127–132. PubMed PMC

Doležel J, Gödhe W. Sex determination in dioecious plants Melandrium album and M. rubrum using high-resolution flow-cytometry. Cytometry. 1995;19:103–106. PubMed

Evans GM, Rees H. Mitotic cycles in dicotyledons and monocotyledons. Nature. 1971;233:350–351. PubMed

Gaut BS. Evolutionary dynamics of grass genome. New Phytologist. 2002;154:15–28.

Gregory TR, Nicol JA, Tamm H, Kullman B, Kullman K, Leitch IJ, et al. Eukaryotic genome size databases. Nucleic Acids Research. 2007;35(Sp. Iss.):D332–D338. PubMed PMC

Greilhuber J. Intraspecific variation in genome size: a critical reassessment. Annals of Botany. 1998;82(Suppl. A):27–35.

Greilhuber J. Intraspecific variation in genome size in Angiosperms: identifying its existence. Annals of Botany. 2005;95:91–98. PubMed PMC

Greilhuber J, Temsch EM, Loureiro JCM. Nuclear DNA content measurement. In: Doležel J, Greilhuber J, Suda J, editors. Flow cytometry with plant cells: analysis of genes, chromosomes and genomes. Weinheim, Germany: Wiley-VCH; 2007. pp. 67–101.

Gupta PK, Rees H. Tolerance of Lolium hybrids to quantitative variation in nuclear DNA. Nature. 1975;257:587–588. PubMed

Hutchinson J, Rees H, Seal G. An assay of the activity of supplementary DNA in Lolium. Heredity. 1979;43:411–421.

Kalendar R, Tanskanen J, Immonen S, Nevo E, Schulman AH. Genome evolution of wild barley (Hordeum spontaneum) by BARE-1 retrotransposon dynamics in response to sharp microclimatic divergence. Proceedings of the National Academy of Sciences of the USA. 2000;97:6603–6607. PubMed PMC

Lang G. Quartäre Vegetationsgeschichte Europas. Jena: Gustav Fischer; 1994.

Leitch IJ, Soltis DE, Soltis PS, Bennett MD. Evolution of DNA amounts across land plants (embryophyta) Annals of Botany. 2005;95:207–217. PubMed PMC

Li W, Zhang P, Fellers JP, Friebe B, Gill BS. Sequence composition, organisation, and evolution of the core Triticeae genome. Plant Journal. 2004;40:500–511. PubMed

McMaster GS. Phenology, development, and growth of the wheat (Triticum aestivum L.) shoot apex: a review. Advances in Agronomy. 1997;59:63–118.

McMaster GS. Phytomers, phyllochrons, phenology and temperate cereal development. Journal of Agricultural Science. 2005;143:137–150.

Michaelson MJ, Price HJ, Ellison JR, Johnston JS. Comparison of plant DNA contents determined by Feulgen microspectrophotometry and laser flow-cytometry. American Journal of Botany. 1991;78:183–188.

Nemoto K, Morita S, Baba T. Shoot and root development in rice related to the phyllochron. Crop Science. 1995;35:24–29.

Price HJ, Chambers KL, Bachmann K, Riggs J. Inheritance of nuclear 2C DNA content variation in intraspecific and interspecific hybrids of Microseris (Asteraceae) American Journal of Botany. 1983;70:1133–1138.

Price HJ, Chambers KL, Bachmann K, Riggs J. Patterns of mean nuclear DNA content in Microseris douglasii (Asteraceae) Botanical Gazette. 1986;147:496–507.

Rayburn AL, Birdar DP, Bullock DG, McMurphy LM. Nuclear DNA content in F1 hybrids of maize. Heredity. 1993;70:294–300.

SanMiguel P, Bennetzen JL. Evidence that a recent increase in maize genome size was caused by the massive amplification of intergene retrotransposons. Annals of Botany. 1998;82:37–44.

SanMiguel P, Tikhonov A, Jin YK, Motchoulskaia N, Zakharov D, MelakeBerhan A, et al. Nested retrotransposons in the intergenic regions of the maize genome. Science. 1996;274:765–768. PubMed

Silvertown JW, Lovett Doust J. Introduction to plant population biology. Oxford: Blackwell Scientific Publications; 1993.

Šmarda P. DNA ploidy levels and intraspecific DNA content variability in Romanian fescues (Festuca, Poaceae) measured in fresh and herbarium material. Folia Geobotanica. 2006;41:417–432.

Šmarda P, Bureš P. Intraspecific DNA content variability in Festuca pallens on different geographical scales and ploidy levels. Annals of Botany. 2006;98:665–678. PubMed PMC

Šmarda P, Kočí K. Chromosome number variability in Central European members of the Festuca ovina and F. pallens groups (sect. Festuca) Folia Geobotanica. 2003;38:65–95.

Šmarda P, Bureš P, Horová L. Random distribution pattern and non-adaptivity of genome size in a highly variable population of Festuca pallens. Annals of Botany. 2007;a 100:141–150. PubMed PMC

Šmarda P, Šmerda J, Knoll A, Bureš P, Danihelka J. Revision of Central European taxa of Festuca ser. Psammophilae Pawlus: morphometrical, karyological and AFLP analysis. Plant Systematics and Evolution. 2007;b 266:197–232.

Šmarda P, Bureš P, Horová L. Genome size and GC content evolution of Festuca: ancestral expansion and subsequent reduction. Annals of Botany. 2008;101:421–433. PubMed PMC

StatSoft, Inc. STATISTICA (data analysis software system), version 7.1. 2005. http://www.statsoft.com .

Vitte C, Bennetzen JL. Analysis of retrotransposon structural diversity uncovers properties and propensities in angiosperm genome evolution. Proceedings of the National Academy of Sciences of the United States of America. 2006;103:17638–17643. PubMed PMC

Vitte C, Panaud O. LTR retrotransposons and flowering plant genome size: emergence of the increase/decrease model. Cytogenetic and Genome Research. 2005;110:91–107. PubMed

Role of adaptive and non-adaptive mechanisms forming complex patterns of genome size variation in six cytotypes of polyploid Allium oleraceum (Amaryllidaceae) on a continental scale