The ability of plant species to colonize new habitats and persist in changing environments depends on their ability to respond plastically to environmental variation and on the presence of genetic variation, thus allowing adaptation to new conditions. For invasive species in particular, the relationship between phenotypic trait expression, demography, and the quantitative genetic variation that is available to respond to selection are likely to be important determinants of the successful establishment and persistence of populations. However, the magnitude and sources of individual demographic variation in exotic plant populations remain poorly understood. How important is plasticity versus adaptability in populations of invasive species? Among environmental factors, is temperature, soil nutrients, or competition most influential, and at what scales and life stages do they affect the plants? To investigate these questions we planted seeds of the exotic annual plant Erodium brachycarpum into typical pasture habitat in a spatially nested design. Seeds were drawn from 30 inbred lines to enable quantification of genetic effects. Despite a positive population growth rate, a few plants (0.1 %) produced >50 % of the seeds, suggesting a low effective population size. Emergence and early growth varied by genotype, but as in previous studies on native plants, environmental effects greatly exceeded genetic effects, and survival was unrelated to genotype. Environmental influences shifted from microscale soil compaction and litter depth at emergence through to larger-scale soil nutrient gradients during growth and to competition during later survival and seed production. Temperature had no effect. Most demographic rates were positively correlated, but emergence was negatively correlated with other rates.
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We thank Frederik Sagemueller, Jay Sexton, and Kara Moore for helping us plant the experiment, and Kara Moore and Kent Holsinger for commenting on manuscript drafts. Brooke Jacob’s work was supported by The Center for Population Biology at UC Davis, an International Postdoctoral Fellowship from the National Science Foundation, and the UC Davis Department of Plant Sciences. The experiment complied with the current laws of the country where it was performed.
Baythavong BS, Stanton ML (2010) Characterizing selection on phenotypic plasticity in response to natural environmental heterogeneity. Evolution 64:2904–2920PubMedGoogle Scholar
Baythavong BS, Stanton ML, Rice KJ (2009) Understanding the consequences of seed dispersal in a heterogeneous environment. Ecology 90:2118–2128PubMedCrossRefGoogle Scholar
Beckage B, Clark JS (2003) Seedling survival and growth of three forest tree species: the role of spatial heterogeneity. Ecology 84:1849–1861CrossRefGoogle Scholar
Bell G, Lechowicz MJ (1991) The ecology and genetics of fitness in forest plants.1. Environmental heterogeneity measured by explant trials. J Ecol 79:663–685CrossRefGoogle Scholar
Booy G, Hendriks RJJ, Smulders MJM, Van Groenendael JM, Vosman B (2000) Genetic diversity and the survival of populations. Plant Biol 2:379–395CrossRefGoogle Scholar
Burnham KP, Anderson D (2002) Model selection and multimodel inference: a practical information-theoretic approach, 2nd edn. Springer, New YorkGoogle Scholar
Campbell DR (1997) Genetic and environmental variation in life-history traits of a monocarpic perennial: a decade-long field experiment. Evolution 52:373–382CrossRefGoogle Scholar
Chevin LM, Lande R, Mace GM (2010) Adaptation, plasticity, and extinction in a changing environment: towards a predictive theory. PLoS Biol 8:e1000357PubMedCrossRefGoogle Scholar
Condit R, Sukumar R, Hubbell SP, Foster RB (1998) Predicting population trends from size distributions: a direct test in a tropical tree community. Am Nat 152:495–509PubMedCrossRefGoogle Scholar
Dobrowski SZ (2011) A climatic basis for microrefugia: the influence of terrain on climate. Glob Change Biol 17:1022–1035CrossRefGoogle Scholar
Fiz-Palacios O, Vargas P, Vila R, Papadopulos AS, Aldasoro JJ (2010) The uneven phylogeny and biogeography of Erodium (Geraniaceae): radiations in the Mediterranean and recent recurrent intercontinental colonization. Ann Bot 106:871–884PubMedCrossRefGoogle Scholar
Gelman A, Hill J (2007) Data analysis using regression and multilevel/hierarchical models. Cambridge University Press, New YorkGoogle Scholar
Grubb PJ (1977) The maintenance of species richness in plant communities: the importance of the regeneration niche. Biol Rev 52:107–145CrossRefGoogle Scholar
Ibanez I, Clark JS, Dietze MC (2008) Evaluating the sources of potential migrant species: implications under climate change. Ecol Appl 18:1664–1678PubMedCrossRefGoogle Scholar
Jacobs BS, Latimer AM (2012) Analyzing reaction norm variation in the field vs. greenhouse: comparing studies of plasticity and its adaptive value in two species of Erodium. Perspect Plant Ecol Evol Syst. http://dx.doi.org/10.1016/j.ppees.2012.04.002
Jongejans E, de Kroon H, Tuljapurkar S, Shea K (2010) Plant populations track rather than buffer climate fluctuations. Ecol Lett 13:736–743PubMedCrossRefGoogle Scholar
Lechowicz MJ, Bell G (1991) The ecology and genetics of fitness in forest plants. 2. Microspatial heterogeneity of the edaphic environment. J Ecol 79:687–696Google Scholar
Mazer SJ (1989) Family mean correlations among fitness components in wild radish: controlling for maternal effects on seed weight. Can J Bot 67:1890–1897CrossRefGoogle Scholar
McMahon SM, Diez JM (2007) Scales of association: hierarchical linear models and the measurement of ecological systems. Ecol Lett 10:437–452PubMedCrossRefGoogle Scholar
Mitchell-Olds T (1986) Quantitative genetics of survival and growth in Impatiens capensis. Evolution 40:107–116CrossRefGoogle Scholar