Environmental factors, not phylogenetic relationships, drive reproductive phenology of closely related Myrcia species (Myrtaceae) in Brazilian coastal forest

Abstract Understanding the factors shaping phenological patterns is essential to unravel species coexistence and biodiversity dynamics. This study investigated the phylogenetic and climatic drivers of reproductive phenology in Myrcia species from the Restingas of the Atlantic Forest in northeastern Brazil. We monitored the reproductive phenology of nine sympatric Myrcia species for one year and assessed the influence of climatic variables (precipitation and day length) and phylogenetic relatedness using phylogenetic signal metrics and eigenvector regression. Our findings indicate a strong climatic control over reproductive phenology. Flowering predominantly occurred during periods of lower precipitation and longer days, whereas fruiting was concentrated in the rainy season. Day length significantly influenced floral bud and flowering activity, whereas precipitation negatively affected these phases but promoted fruit maturation. Despite the close phylogenetic relationships among species, we found no significant phylogenetic signal in phenological traits, suggesting that reproductive timing is shaped more by environmental factors than by evolutionary history. The lack of phylogenetic conservatism in phenology highlights the role of ecological adaptation in shaping reproductive strategies in this diverse community. Although temporal overlap among species was observed, it did not align with phylogenetic relatedness, suggesting that competition or facilitation mechanisms operate independently of evolutionary history. These findings highlight how tropical plant communities adjust their reproductive cycles in response to environmental constraints, reinforcing the dominant role of ecological factors over phylogenetic constraints in shaping phenological patterns.