As the environment changes, so too must plant communities and populations if they are to persist. Life history transitions and their timing are often the traits that are most responsive to changing environmental conditions. To clarify the effect of selection and environment on the phenology of germination and reproductive commencement, we performed a quantitative genetic study of phenotypic selection on Chamaecrista fasciculata (Fabaceae). A population of pedigreed individuals was planted into a restored prairie experimental garden in each of two years. Over two parental generations and one progeny generation, the earliest dates of germination and flowering were tracked for paternal families.
Results/Conclusions
In this population, selection for advancement in reproductive stage was detected, as well as a response of 2.2 days earlier flowering in the second generation. Germination phenology varied more between years than between generations, and there is genetic variation for plasticity of germination phenology. The effect of the environment was the strongest contributor to differences in phenology. Response to selection became apparent when accounting for the effect of the environment on phenotypic differences, highlighting the importance of controlling for year-to-year environmental variation in quantitative genetic studies.