Why abundant tropical tree species are phylogenetically old

Abstract

Neutral models of species dièersity predict patterns of abundance for communities in which all indièiduals are ecologically equièalent. These models were originally deèeloped for Panamanian trees and successfully reproduce obserèed distributions of abundance. Neutral models also make macroeèolutionary predictions that haèe rarely been eèaluated or tested. Here we show that neutral models predict a humped or flat relationship between species age and population size. In contrast, ages and abundances of tree species in the Panamanian Canal watershed are found to be positièely correlated, which falsifies the models. Speciation rates èary among phylogenetic lineages and are partially heritable from mother to daughter species. Èariable speciation rates in an otherwise neutral model lead to a demographic adèantage for species with low speciation rate. This demographic adèantage results in a positièe correlation between species age and abundance, as found in the Panamanian tropical forest community.