An evolutionary approach to understanding drought-resistance in Neotropical trees

Abstract

Drought intensity and severity have increased in the last decades and drier climates are predicted to become more common in the tropics, which can lead to an expansion of seasonally dry ecosystems worldwide. However, the functional strategies that allow plants to cope with increasingly drier conditions in seasonally dry ecosystems remain poorly understood, especially in the Neotropics. To explore the evolution of tree traits underpinning the ability to persist in limited water availability conditions, we will assemble a species-level database of deciduousness, height, leaf thickness, seed mass and xylem embolism resistance for Neotropical species from seasonally dry ecosystems. To model the evolution of traits, we will combine these data with dated molecular phylogenies already available or generated for our species dataset. Through this eco- evolutionary (i.e. species' traits along with their evolutionary history) approach, we aim to unravel the main traits underlying drought resistance strategies that have allowed lineages to successfully colonize and diversify in Neotropical seasonally dry ecosystems (i.e. Cerrado and seasonally dry forests). The proposed study will address fundamental knowledge gaps that have precluded a better understanding of plant diversity and assembly in Neotropical seasonally dry ecosystems over time: 1) How do morphological and physiological traits influence drought resistance strategies in Neotropical trees of seasonally dry ecosystems?; 2) Is there a phylogenetic signal in these traits or they are a result of convergent evolution?; 3) Are the hydraulic strategies to cope with drought distinct between Cerrado and seasonally dry forest lineages? These issues are also important in the context of restoration as the maintenance of high levels of phylogenetic diversity can improve success through maintaining the evolutionary potential of species and thus ensuring that ecosystem functions and services have a higher likelihood to be sustained through time. Our findings will I) fill the knowledge gap about how traits related to drought resistance influenced the diverse assembly of the Neotropical seasonally dry ecosystems flora, as well as; II) provide an overview of the potential tree species and lineages that can be useful in restoration plans, within the NERC-FAPESP project to which this proposal is linked, by exhibiting drought-resistance traits. (AU)