Reproductive consequences of variation in flowering phenology in the dry forest tree Enterolobium cyclocarpum in Guanacaste, Costa Rica

Abstract

Premise of the Study Flowering initiation, duration and magnitude, and degree of flowering synchrony within a population can affect the reproductive fitness of individuals. We examined the flowering phenology within a population of the tropical dry forest Guanacaste tree (Enterolobium cyclocarpum) to gauge the impact of phenological variation among trees on fruit production and progeny vigor. Methods We monitored the flowering phenology of 93 trees weekly during 2005, 2006, and 2007, using a scale based on the percentage of the crown with open flowers. We also monitored fruit production for each tree in 2005, 2006, 2007, and 2008. Finally, we evaluated the relationship between phenological variation and progeny performance. Key Results Ten measures of flowering phenology and synchrony among flowering trees, based on the number of weeks when anthesis of the crown exceeded 50%, were used to develop four phenological profiles. These profiles were correlated with significant differences in fruit production and progeny vigor. Trees with flowers in >50% of their crown for at least 2 weeks produced more fruits and more vigorous progeny than trees with other profiles. Trees also tended to produce the same phenological profile among years than predicted by chance. Conclusions Guanacaste trees vary significantly in the initiation of anthesis, duration and magnitude of flowering, and degree of synchrony among trees. Trees also tend to maintain the same flowering profile among years. Finally, the flowering behavior of E. cyclocarpum leads to significant differences in fruit and seed production, germination, and early progeny growth.

Shifts in phenological mean and synchrony interact to shape competitive outcomes

“…, Rocha et al. , Shima et al. ), and our results show individual variation in hatching could buffer survival across good and bad conditions.…”

“…Overall, the results indicate maintenance of low phenological synchrony within populations as a bet-hedging strategy. Bet-hedging life-history strategies increase fitness in unpredictable environments (Tarazona et al 2017, Rocha et al 2018, Shima et al 2018, and our results show individual variation in hatching could buffer survival across good and bad conditions. By "putting all their eggs in one basket," highly synchronized populations run a great risk of mistiming because all individuals are affected.…”

“…1, or alternatively, favorable environmental conditions) or bad (e.g., late arrival relative to competitor, or harsh environmental conditions). Alternatively, low-synchrony populations spread individuals across good and bad conditions, akin to bet hedging (Wilbur et al 2006, Tarazona et al 2017, Rocha et al 2018, Shima et al 2018. Therefore, differences in synchrony could strongly affect the outcome of shifts in mean phenology-a highsynchrony population might be more sensitive to shifts in phenological mean because all individuals shift to experience a new condition, whereas low synchrony might be more robust to shifts in phenological mean.…”

Phenological patterns from two sympatric subspecies of the palm Geonoma cuneata (H. Wendl. ex Spruce) and their gall inductor Contarinia geonomae (Gagné)

“…Moreover, heavy rain could dilute nectar and degrade pollen therefore reducing pollination chances (Lawson & Rands, 2019). Increasing flowering synchrony can maximize the chances of pollination and individual reproductive success (Rocha et al, 2018). The flowering biology of G. cuneata has characteristics that make it susceptible to low pollination success and, therefore, to pressure for higher synchrony.…”

Remotely sensed assessment of increasing chronic and episodic drought effects on a Costa Rican tropical dry forest

“…The delayed leaf flushing due to the late rains may have led to a late flowering period in 2017. This is possible since individuals could differ in their flowering phenology and their flowering magnitude even within a small spatial extent (Rocha et al 2018). However, the presence of pale-colored pixels may be too showy, since flowers are usually hidden by the new leaves (Figs.…”