Macroevolutionary Patterns of Phytochemical Diversity in a Macaronesian Archipelago

Abstract

Aim Plant specialised metabolites are highly diverse and serve various functions, yet the different forms of phytochemical complexity and their drivers are often not fully understood. In this context, islands provide a valuable opportunity to explore the drivers of phytochemical diversity and its adaptive significance, owing to their unique physical features and markedly different biotic and abiotic pressures compared to the mainland. Location Macaronesian region. Time Period Contemporary. Major Taxa Studied Vascular plants. Methods We investigated macroevolutionary patterns in the diversity of plant specialised chemistry by conducting metabolomic analyses of leaf samples from 54 species on the Canary Islands. Our goal was to determine whether the mean crown node age, which relates to a species' island residence time, influences phytochemical diversity. To gain mechanistic insight into selective abiotic pressures, we also examined whether temperature and precipitation, associated with species' climatic niches, affected phytochemical diversity. Results Crown age did not correlate with overall phytochemical diversity but did influence the production of specific metabolite groups, with some types of compounds showing a positive correlation and others a negative correlation with crown age. Temperature and precipitation played significant roles in shaping phytochemical diversity, with temperature having a negative influence and precipitation exerting a positive effect. Both climatic factors also affected the levels of specific compound groups, driving either an increase or decrease depending on the metabolite type. Main Conclusions Our findings reveal novel linkages between phytochemical diversity, climate and species residence time on islands, suggesting evolutionary processes that lead to divergent patterns of plant phytochemical complexity. Exploring these evolutionary mechanisms and the extent to which these patterns represent adaptive responses (e.g., to climate) can ccontribute to advancing our understanding of phytochemical variation.

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