Distribution of leaflet traits across different habitats: a phylogenetically controlled test using Neotropical palms

Traits associated with resource acquisition and use are related to current or past environmental conditions. Consequently, similar environments are occupied by closely related lineages or by different lineages that have converged to occupy them. Understanding how functional traits vary in relation to environmental gradients facilitates a more predictive ecology of the Anthropocene. We investigated whether leaflet traits of palm species are phylogenetically conserved and how this influences their distribution in the Neotropics. We measured specific leaflet area (SLA) and leaf thickness in 79 Neotropical palm species. We then assessed the relationship between these variables and their distribution at different habitat type scales using phylogenetically controlled linear mixed models. Phylogenetically close species showed greater similarities in SLA and lower similarities in leaflet thickness than expected from their phylogenetic relationships. Species from open habitats and forest canopy species had thick leaves and low SLA, while the opposite was found for understorey species. Phylogenetic conservatism in SLA combined with phylogenetic divergence in leaflet thickness reveals leaflet trade-off strategies in palms and is related to their distribution in the Neotropics. Anthropogenic impacts may threaten understorey species in particular, which in the long-term may cause homogenisation of palm communities and loss of functional diversity.</p