Abstract
Environmental sex determination (ESD) − a change in sexual function during an individual life span drivenby environmental cues − is an exceedingly rare sexual system among angiosperms. Because ESD candirectly affect reproduction success, it could influence diversification rate as compared with lineages thathave alternative reproductive systems. Here we test this hypothesis using a solid phylogenetic frameworkof Neotropical Catasetinae, the angiosperm lineage richest in taxa with ESD. We assess whether gains ofESD are associated with higher diversification rates compared to lineages with alternative systems whileconsidering additional traits known to positively affect diversification rates in orchids. We found thatESD has evolved asynchronously three times during the last ~5 Myr. Lineages with ESD have consistentlyhigher diversification rates than related lineages with other sexual systems. Habitat fragmentation due tomega-wetlands extinction, and climate instability are suggested as the driving forces for ESD evolution.