Galloway, Laura , Burgess, Kevin .
Maternal effects influence life history evolution: Cross-generation associations between flowering phenology and timing of germination.
Maternal plants may influence trait expression in their offspring. We present the results of a series of studies that explored the contribution of maternal effects to life history evolution in Campanulastrum americanum, an understory herb. In C. americanum, fall germinating seeds grow as annuals while those that germinate in the spring have a biennial schedule. We used genetic and environmental manipulations to alter maternal flowering time, testing the hypothesis that maternal flowering time influences timing of offspring germination and hence life history schedule. We found life history schedule is maternally inherited with its evolution determined by both maternal and offspring generations. Specifically, plants that flowered early through environmental manipulation or artificial selection shifted their entire reproductive phenology, maturing seeds earlier than those manipulated to flower late. Seeds planted early, simulating dispersal from early flowering plants, had greater germination as annuals while those planted late, as though from late flowering plants, had greater germination as biennials. Therefore, both environmental and genetic influences on flowering time determine offspring life history schedule. Seeds from early-flowering selection lines had 43% greater germination as annuals, while those from late-flowering lines produced equivalent numbers of annual and biennial offspring. This indicates a positive genetic correlation between timing of flowering and season of germination in early produced seeds. As a consequence, maternal effects are expected to accelerate response to selection that favors fall germinating annuals. In total, cross-generation effects are an integral part of the expression and evolution of life history variation in this species.
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1 - University of Virginia, Department of Biology, Charlottesville, Virginia, 22904-4328, USA
2 - Columbus State University, Department of Biology, Columbus, GA, 31907-5645
Life history evolution
indirect genetic effects
Presentation Type: Oral Paper:Papers for Sections
Date: Tuesday, July 29th, 2008
Time: 2:30 PM