Data and code from: Functional traits drive speciation in tropical palms through complex interactions between genome size, adaptation and allometry

Speciation shapes biodiversity, yet why some lineages diversify faster
than others remains unclear. Theory predicts that traits promote
ecological speciation through adaptation, but their evolvability (‘trait
flexibility’) may be impacted by allometric and genomic constraints. Here
we test this by integrating phylogenetic, trait and genome size data for
palms (Arecaceae) – a large pantropical family (>2,600 species)
with 167-fold variation in certain traits (e.g., fruit size) and 60-fold
genome size variation. Using structural equation modelling, we test three
hypotheses: trait evolution promotes speciation (H1: trait flexibility
hypothesis), and, speciation and trait evolution rates are constrained by
allometry (H2: allometric constraint hypothesis) and genome size (H3:
large genome constraint hypothesis). We detected seven major speciation
rate shifts during ~110-million-years of palm evolution. Tip-derived
speciation rates increased with faster evolution in leaf size and plant
height, supporting H1, whereas correlated evolution between all traits
indirectly influenced speciation, supporting H2. Large genomes decreased
plant height and stem diameter evolution rates, supporting H3, but the
genome size-speciation association was sensitive to phylogenetic
autocorrelation. Our findings illustrate how the interplay between genome
size, allometry and trait evolvability affect speciation, emphasizing the
importance of holistic approaches for uncovering general mechanisms
driving speciation throughout the Tree of Life.