School of Science and Technology

Flowering times of plants are important life-history components and it has previously been hypothesized that
flowering phenologies may be currently subject to natural selection or be selectively neutral. In this study we
reviewed the evidence for phenotypic selection acting on flowering phenology using ordinary and phylogenetic
meta-analysis. Phenotypic selection exists when a phenotypic trait co-varies with fitness; therefore, we looked
for studies reporting an association between two components of flowering phenology (flowering time or
flowering synchrony) with fitness. Data sets comprising 87 and 18 plant species were then used to assess the
incidence and strength of phenotypic selection on flowering time and flowering synchrony, respectively. The
influence of dependence on pollinators, the duration of the reproductive event, latitude and plant longevity as
moderators of selection were also explored. Our results suggest that selection favours early flowering plants,
but the strength of selection is influenced by latitude, with selection being stronger in temperate environments.
However, there is no consistent pattern of selection on flowering synchrony. Our study demonstrates that
phenotypic selection on flowering time is consistent and relatively strong, in contrast to previous hypotheses of
selective neutrality, and has implications for the evolution of temperate floras under global climate change.