Concluding remarks
To obtain accurate estimates of phenotypic selection, it is essential to
consider also selection via correlated traits (Lande and Arnold 1983).
Yet, selection on the timing of life-cycle events is rarely estimated
comprehensively enough to detect indirect selection via other
phenological traits or correlational selection on trait combinations.
Our results show that correlations between reproductive and vegetative
phenology, in combination with contrasting selection on these two
traits, can affect selection on flowering phenology, although the
direction of selection on flowering time remained the same in our study.
More generally, the results illustrate that selection on phenological
traits can only be fully understood from the perspective of the seasonal
development cycle. Yet, we still know little about the relationships
among temporally correlated life history events, and the importance of
these events for fitness. Insights into the extent to which selection on
the timing of seasonal events is influenced by selection on temporally
correlated events are also essential to understand long-term responses
to anthropogenic climate change, as climate is likely to influence the
phenotypic expression of sequential seasonal events as well as the
optimal timing of these events (Li et al. 2016, Zohner et al. 2018,
Mohan 2019).