PARENTAL ENVIRONMENTAL EFFECTS ON LIFE HISTORY IN THE HERBACEOUS PLANTCAMPANULA AMERICANA

Abstract

Although environmental parental effects, especially maternal effects, are well known in plants we have almost no information about their expression in nature. This study explores the influence of maternal and paternal light and nutrient environments on germination characters under natural conditions in the herbaceous plant Campanula americana. Families were grown in a greenhouse under three levels of light or three levels of nutrients, and crosses were conducted within each environmental gradient to produce seeds with all combinations of maternal and paternal environments. Seeds produced under the controlled environments were planted into the home site of the population and another local site, and germination was monitored over the fall and spring germinating seasons. The paternal light environment influenced percentage germination, demonstrating that the offspring phenotype may depend on the environment a set of pollen donors is grown in. The effect of maternal nutrient level on percentage germination depended on the offspring environment. Percentage germination in response to maternal nutrient and paternal light environments varied among families, suggesting that these parental environmental effects are genetically variable. Both maternal light and nutrient environments influenced season of germination. Germination season determines life history in C. americana: fall-germinating individuals are annuals while spring-germinating seeds are biennials. Maternal plants grown under low and high light and low nutrient conditions produced more biennial offspring while the remaining maternal environments had an equal frequency of annual and biennial offspring. In C. americana maternal environments influence life history and therefore fitness through their effects on season of germination.