The genetic and environmental control of reproductive timing in a short-lived monocarpic species Daucus carota (Umbelliferae)

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Elizabeth P. Lacey, Professor (Creator)
The University of North Carolina at Greensboro (UNCG )
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Abstract: (1) Offspring of annual, biennial and triennial Daucus carota were grown under three nutrient regimes in a growth chamber to measure the effects of nutrient supply and maternal age of flowering on offspring size and growth rate and the effects of all four variables on year of flowering. (2) Offspring rosette size and recent growth rate were both good predictors of year of flowering. An increase in size but a decrease in relative growth at the end of the summer were associated with an increased probability of flowering in the next season. The results are consistent with the Wilbur—Collins model, which suggests that both size and recent growth rate influence reproductive timing and that individuals track resources by delaying the year of reproduction if resources abound or by accelerating reproduction if resources become limiting. This model, although proposed for amphibians, may describe the general relationship between growth and reproductive timing in monocarpic plants. (3) Maternal age and nutrient supply influenced rosette size, relative growth rate, and flowering time. Annual maternal plants and high nutrients produced both the largest offspring and the greatest number of annuals. Also, the maternal contribution acted directly upon the year of flowering as well as indirectly through size and recent growth. Both genetic variability and habitat heterogeneity explain the variation in year of flowering in natural populations. (4) The results provide evidence that the early-rosette growth rate and the length of the pre-reproductive period are negatively correlated, as predicted by theories about the evolution of life-history patterns. Rapid growth may help annuals to persist in habitats which generally favour biennials. (5) Response to nutrient supply did not vary among maternal age groups as might be expected in colonizing species. This suggests that phenotypic plasticity in response to nutrient supply evolves independently of year of reproduction.

Additional Information

Journal of Ecology 74(1): 73-86
Language: English
Date: 1986
Daucus carota, Nutrient supply, Reproductive timing, Maternal age, Growth rate, Environmental control, Genetic control

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