Premise of the study
Defense investment in plant reproductive structures is relatively understudied compared to the defense of vegetative organs. Here the evolution of chemical defenses in reproductive structures is examined in light of the optimal defense, apparency, and resource availability hypotheses within the genus Cornus using a phylogenetic comparative approach in relation to phenology and native habitat environmental data.

Methods
Individuals representing 25 Cornus species were tracked for reproductive phenology over a full growing season at the Arnold Arboretum of Harvard University. Floral, fruit, and leaf tissue was sampled to quantify defensive chemistry as well as fruit nutritional traits relevant to bird dispersal. Native habitat environmental characteristics were estimated using locality data from digitized herbarium records coupled with global soil and climate datasets.

Key Results
The evolution of later flowering was correlated with increased floral tannins, and the evolution of later fruiting was correlated with increased total phenolics. Leaves were observed to contain the highest tannin activity while inflorescences contained the highest total flavonoids. Multiple aspects of fruit defensive chemistry were correlated with fruit nutritional traits. Floral and fruit defensive chemistry were evolutionarily correlated with aspects of native habitat temperature, precipitation, and soil characteristics.

Conclusions
Results provide tentative support for the apparency hypothesis with respect to both flower and fruit phenology, while relative concentrations of secondary metabolites across organs provide mixed support for the optimal defense hypothesis. The evolution of reproductive defense with native habitat provides at best mixed support for the resource availability hypothesis.

Common garden experiment using the Arnold Arboretum collections of Cornus - standardized phenology assessment with controlled sampling of reproductive tissues to collect phenotypic data on inflorescences and fruits. Native habitat data for each species obtained from Mason et al. 2020 (International Journal of Plant Sciences) using digitized herbarium record occurrence points to extract climate and soil data from global data layers. Phylogeny used obtained from Mason et al. 2020, itself reconstructed from data published in Xiang et al. 2006. See full article for complete methodological details.

Please see full text of the journal article and supplementary materials for full details on methodology. Also, if needed feel free to contact the corresponding author (Chase Mason) with any questions about the suitability of specific data types for re-use for other purposes. Phenotypic data are straightforward, though specific to the common garden study context. Authors would recommend others obtain the phylogeny and environmental data from the original sources if being used for a divergent purpose.