GALLOWAY, LAURA F. Department of Biology, University of Virginia, Charlottesville VA 22903. - Maternal and paternal environmental effects on seed characters in Campanula americana.
The maternal and paternal environment may affect offspring phenotype,
potentially influencing both the rate and direction of evolutionary
change. I explored parental environmental effects on seed characters
in Campanula americana (Campanulaceae), a woodland herb with a
variable life history. Germination time determines whether
individuals are winter annuals or biennials, therefore parental
environmental effects on seed characters may influence life history.
Maternal families from two populations were grown in a controlled
environment under 3 light levels and 3 levels of soil nutrient. Nine
seed types were produced for each population (3 maternal treatments x
3 paternal treatments) for both the light and nutrient gradients.
Seeds were individually weighed and germinated under controlled
conditions. Overall seed weight increased as maternal environmental
conditions became more favorable for both the light and nutrient
gradients, but the response varied among populations and maternal
families. In one population the paternal light environment affected
seed weight when maternal light was limited. A germination study with
only 2 maternal and 1 paternal light and nutrient environments found
reduced early germination in seeds produced under favorable maternal
nutrient conditions; parental light environment did not affect
germination. Results of subsequent germination studies will also be
discussed. Both maternal, and to a lesser extent, paternal
environments influence seed characters and as a consequences may
affect life history in C. americana.
Key words: Campanula americana, environmental effects, genetic variation, maternal effects, seed ecology