Simultaneous selection on vegetative and reproductive phenology in a perennial herb

Abstract

The timing of different life history events are often correlated, and selection might only rarely be exerted independently on the timing of a single event. In plants, phenotypic selection has often been shown to favour earlier flowering. However, little is known about to what extent this selection acts directly vs. indirectly via vegetative phenology, and if selection on the two traits is correlational. We estimated direct, indirect and correlational phenotypic selection on vegetative and reproductive phenology over three years for the perennial herb Lathyrus vernus. Direct selection favoured earlier flowering and shorter timespans between leaf-out and flowering in all years. However, early flowering was associated with early leaf-out, and the direction of selection on leaf-out day varied among years. As a result, selection on leaf-out weakened selection for early flowering in one of the study years. We found no evidence of correlational selection. Our results highlight the importance of including temporally correlated traits when exploring selection on the phenology of seasonal events.