Agave sensu lato appeared around 8 Mya. The best supported diversification model for Agavoidae shows two shifts around 8 Mya. Agave sensu lato speciation rate has been increasing towards the present. Nectarivorous bats from the Glossophaginae subfamily originated around 7 Mya. Agave and their pollinating bats share a diffuse coevolutionary history.
As angiosperms became one of the megadiverse groups of macroscopic eukaryotes, they forged modern ecosystems and promoted the evolution of extant terrestrial biota. Unequal distribution of species among lineages suggests that diversification, the process that ultimately determines species richness, acted differentially through angiosperm evolution.
Fouqueriaceae, the family of ocotillo and bojum tree, is a monogeneric clade with 11 species. Its siter group, the plox family, Polemoniaceae, has a diversity of 400 species. In this paper, we investigate the processes that have determined the species diversity of Fouquieriaceae.
Theory suggests that phylogenetic structure, age type (crown or stem age), and taxonomic delimitation can affect estimates of the age–richness correlation (ARC) considerably. Results from this paper warn against direct interpretations of single ARC estimates and advocate for a more integrative use of ARCs across age types and taxonomic ranks in diversification studies.