On the evolution of fleshy fruits: an integrative test to assess the relative role of intrinsic and extrinsic factors in shaping fruit type
A trip to a grocery store exposes us to an outstanding diversity of fruits. While this variety was influenced by human selection during plant domestication, it mainly reflects strategies of seed dispersal that evolved over millions of years. Despite the huge variation in fruit color, shape, and size, common patterns can still be identified, especially the repeated evolution of fleshy fruits (e.g. olives, apples, tomatoes). Though this pattern is well observed, we are still exploring the role of different factors and their selective pressures. These can be intrinsic, as evolution of inherited genes determining fruit traits, or extrinsic, as the environment. To date, studies have focused on one or two major factors at a time, but their relative contributions requires an integrative analysis.
FRUITFUL will dissect the evolution of fleshy fruits in the olive family. Oleaceae is the ideal study subject here because it presents a natural comparative set-up for fruit evolution: multiple lineages that independently evolved fleshy fruits; species living in a variety of environments; and diverse seed dispersers. Further, several genomes and transcriptomes of Oleaceae were recently released.
In this project, I will: (1) identify independent transitions to fleshy fruit within a comprehensive phylogenetic framework of Oleaceae; (2) use phylogenomic approaches to analyze representative genes in species with fleshy or dry fruits, and test for switches in selective pressures in relation to trait transitions; (3) estimate the historical biogeography of the family, along with current environmental preferences of species, and their seed dispersers; and finally, (4) integrate all results in models of causal relationships, and identify direct and indirect effects, and their magnitudes, among variables and fruit type. FRUITFUL’s interdisciplinary research and novel integrative approach will provide new insights into understanding the patterns observed at a macroevolutionary scale.