Diversification of Caiophora (Loasaceae subfam. Loasoideae) during the uplift of the Central Andes

Abstract

Andean orogeny and the ecological changes that followed promoted diversification in plant and animal lineages since the Early Miocene. The angiosperm genus Caiophora (Loasaceae, subfam. Loasoideae) comprises around 50 species that are endemic to South America. These are distributed from southern Ecuador to Central Chile and Argentina. Bee pollination and distribution at low-intermediate elevations probably represent the ancestral condition in the lineage that includes Caiophora and its allied genera. The majority of Caiophora species grow at high elevations in the Andes, where some depend on vertebrate pollination. Previous studies did not resolve phylogenetic relationships within Caiophora, which precluded the dating of the origin and divergence of this group. We used markers of one nuclear (ITS) and one plastid region (trnSGCU-trnGUUC) to solve phylogenetic relationships among 19 Caiophora species (including different accessions). We also included 10 species of the allied genera Blumenbachia and Loasa. Aosa rostrata and Xylopodia klaprothioides were used as outgroups. Phylogenetic reconstruction strongly supports the monophyly of Caiophora, and although several clades within this genus are poorly supported, our study yielded a better infra-generic resolution than previous studies. The origin of Caiophora is dated to the Early-Middle Miocene and can be related to the uplift of the Cordilleras Frontal and Principal and to Pacific marine transgressions. According to our estimations, Caiophora began to diversify during the Middle-Late Miocene and this unfolding proceeded eastwards during the Pliocene and the Pleistocene, in parallel to the uplift of different Andean mountain ranges.