Parental Effects in Plantago lanceolata L. I.: A Growth Chamber Experiment to Examine Pre- and Postzygotic Temperature Effects

Abstract

Lacey, E. P. (1996) Parental effects in Plantago lanceolata. L. I. A growth chamber experiment to examine pre-and post-zygotic temperature effects. Evolution 50(2): 865-878. In spite of the potential evolutionary importance of parental effects, many aspects of these effects remain inadequately explained. This paper explores both their causes and potential consequences for the evolution of life-history traits in plants. In a growth chamber experiment, I manipulated the pre-and postzygotic temperatures of both parents of controlled crosses of Plantago lanceolata. All offspring traits were affected by parental temperature. On average, low parental temperature increased seed weight, reduced germination and offspring growth rate, and accelerated onset of reproduction by 7%, 50%, 5%, and 47%, respectively, when compared to the effects of high parental temperature. Both pre-and postzygotic parental temperatures (i.e., prior to fertilization vs. during fertilization and seed set, respectively) influenced offspring traits but not always in the same direction. In all cases, however, the postzygotic effect was stronger. The prezygotic effects were more often transmitted paternally than maternally. Growth and onset of reproduction were influenced both directly by parental temperature as well as indirectly via the effects of parental temperature on seed weight and germination. Significant interactions between parental genotypes and prezygotic temperature treatment (G × E interactions) show that genotypes differ in their intergenerational responses to temperature with respect to germination and growth. The data suggest that temperature is involved in both genetically based and environmentally induced parental effects and that parental temperature may accelerate the rate of evolutionary change in flowering time in natural populations of P. lanceolata. The environmentally induced temperature effects, as mediated through G × (prezygotic) E interactions are not likely to affect the rate or direction of evolutionary change in the traits examined because postzygotic temperature effects greatly exceed prezygotic effects. Key words: Germination, growth, life-history evolution, maternal effects, onset of reproduction, parental effects, paternal effects, Plantago lanceolata, pre-and postzygotic effects, seed weight, temperature Article:Parents can influence the phenotypes of their offspring beyond their direct chromosomal contributions. In many circumstances, the parental environment may transcend the generational barrier to alter the phenotypic expression of fitness traits in offspring (see reviews of plants, Rowe

Intraspecific functional differentiation suggests local adaptation to long‐term climate change in a calcareous grassland

“…Sampling mature individuals also reduced any potential influence of parental effects on offspring phenotype, which are generally more prevalent in juvenile life-history stages relative to adult life-history stages (Roach & Wulff 1987;Weiner et al 1997). This is consistent with studies of P. lanceolata where parental temperature influences germination, growth and reproduction of newly germinated seeds but not survival or reproduction of offspring after 1 year (Lacey 1996;Lacey & Herr 2000). To further reduce any potential influence of parental environment on offspring phenotype, sampled individuals were grown in separate pots in watered and fertilized medium in a glasshouse at Syracuse University, New York, USA, for 6 months before propagation.…”

Selection in Modular Organisms: Is Intraclonal Variation in Macroalgae Evolutionarily Important?

“…While the latter source is nongenetic in the strict sense, persistent intergenerational environmental effects among clonal modules indicate that this "somatic memory" (Schwaegerle et al 2000) yields variation that is effectively heritable and available to selection processes acting on clonal offspring. It may have further evolutionary consequences if phenotypic responses to intergenerational environmental variance are genotype specific or environmentally induced variation becomes fixed within propagative cells (Lacey 1996).…”

Multigenerational Effects of Flowering and Fruiting Phenology in Plantago Lanceolata

“…Greenhouse and growth-chamber studies show that the environment during fertilization and early embryonic development of an offspring while still attached to the maternal parent can influence offspring seed mass and germination (e.g., Riddell and Gries 1958, Koller 1962, Robertson et al 1962, Sawhney and Naylor 1979, Gutterman 1980, Siddique and Goodwin 1980, Wulff 1986, Case et al 1996. It can also influence offspring fitness in the field (Lacey and Herr 2000). The studies cited here examined the specific effects of postzygotic temperature and/or photoperiod on off-spring traits.…”

“…Our study was motivated by Lacey and Herr's (2000) observation that postzygotic temperature can influence offspring fitness in field-grown P. lanceolata. Using two parental temperature regimes that resemble mean monthly temperatures for May and July, during which time P. lanceolata flowers in North Carolina, Lacey and Herr observed that high postzygotic temperature increased offspring fitness by almost 50%.…”