This is an open access article under the terms of the Creat ive Commo ns Attri bution-NonCo mmerc ial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. Abstract 1. Timing of reproduction affects the outcome of interactions between plants and their pollinators, grazers and seed predators, as well as with their local abiotic environment. In seasonal environments, phenotypic selection has often been shown to favour early flowering. Yet, we still know little about the agents driving selection in natural populations and whether observed phenotypic selection corresponds to genotypic selection-a prerequisite for evolutionary change. 2. In this study, we experimentally assessed phenotypic and genotypic selection for flowering time in a natural population of the perennial herb Lathyrus vernus. We transplanted sibling individuals, obtained through controlled crosses, to their source population and found net phenotypic selection for earlier flowering in the field. 3. Despite a higher susceptibility to roe deer grazing, early-flowering plants had higher fruit set and more seeds per fruit than late-flowering plants. We found no support for genotypic selection on flowering time, and heritability for first flowering day was very low. 4. Synthesis. Our results suggest that commonly observed patterns of higher fitness in early-flowering plants do not always correspond to selection on genotypic values and are thus not necessarily expected to result in evolutionary change even if the relationship between flowering time and fitness is causal. This finding should be important to understand how species phenology might respond to changing environmental conditions. K E Y W O R D S evolutionary ecology, fitness components, herbivory, heritability, Lathyrus vernus, natural selection, phenology

Temporal variation in natural selection has profound effects on the evolutionary trajectories of populations. One potential source of variation in selection is that differences in thermal reaction norms and temperature influence the relative phenology of interacting species. We manipulated the phenology of the butterfly herbivore Anthocharis cardamines relative to genetically identical populations of its host plant, Cardamine pratensis, and examined the effects on butterfly preferences and selection acting on the host plant. We found that butterflies preferred plants at an intermediate flowering stage, regardless of the timing of butterfly flight relative to flowering onset of the population. Consequently, the probability that plant genotypes differing in timing of flowering should experience a butterfly attack depended strongly on relative phenology. These results suggest that differences in spring temperature influence the direction of herbivore-mediated selection on flowering phenology, and that climatic conditions can influence natural selection also when phenotypic preferences remain constant.

Premise Climate warming has altered the start and end of growing seasons in temperate regions. Ultimately, these changes occur at the individual level, but little is known about how previous seasonal life‐history events, temperature, and plant‐resource state simultaneously influence the spring and autumn phenology of plant individuals. Methods We studied the relationships between the timing of leaf‐out and shoot senescence over 3 years in a natural population of the long‐lived understory herb Lathyrus vernus and investigated the effects of spring temperature, plant size, reproductive status, and grazing on spring and autumn phenology. Results The timing of leaf‐out and senescence were consistent within individuals among years. Leaf‐out and senescence were not correlated with each other within years. Larger plants leafed out and senesced later, and size had no effect on growing season length. Reproductive plants leafed out earlier and had longer growing seasons than nonreproductive plants. Grazing had no detectable effects on phenology. Colder spring temperatures delayed senescence in two of three study years. Conclusions The timing of seasonal events, such as leaf‐out and senescence in plants can be expressed largely independently within and among seasons and are influenced by different factors. Growing season start and length can often be dependent on plant condition and reproductive status. Knowledge about the drivers of growing season length of individuals is essential to more accurately predict species and community responses to environmental variation.

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.

The timing of different life‐history events is 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 favor earlier flowering. However, little is known about to what extent this selection acts directly versus 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 3 years for flowering individuals of the perennial herb Lathyrus vernus. Direct selection favored 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.