Leaf-Fruit Trait Decoupling Along Environmental Gradients in Tropical Cryptocaryeae (Lauraceae)

Cryptocaryeae, as a significant tribe within the Lauraceae family with important economic and ecological value, comprises over 850 species. Its common ancestor dates back to approximately 123 million years ago, in the early Cretaceous, originating in tropical Africa and Asia. Understanding how leaf and fruit functional traits of Cryptocaryeae trees (Lauraceae) respond to environmental fluctuations is crucial for protecting the structure and function of forest ecosystems. In this study, we investigated the influence of environmental factors on leaf and fruit morphological traits in the tropical tribe Cryptocaryeae. Based on an established phylogenetic framework for Cryptocaryeae, we compiled a dataset containing 17,117 morphological observations across 369 species. The analyzed traits included leaf length, leaf width, leaf area, fruit length, fruit diameter, and fruit size. Through analyzing trends of leaves and fruits morphological traits across the latitude and longitude and their relationship with environmental factors, and by quantifying the relative contributions of environmental factors to these traits, we demonstrated that leaf morphology exhibited distinct latitudinal and longitudinal zonation and was sensitive to environmental fluctuations, especially to temperature changes. In contrast, the change of fruit morphological traits was comparatively conservative in their variation, mainly affected by precipitation. These findings suggest that different plant traits may employ different trade-off strategies during environmental adaptation. Highlighting the importance of integrating ecological and evolutionary perspectives on leaf and fruit morphological traits of tropical Cryptocaryeae trees could provide insights into understanding plant environmental adaptation.