Past Dynamics of Speciation in Andean Mountain Rainforsts

Tropical Andean mountain rainforests harbor extremely high species densities in many animal and plant taxa. This species density could either be related to massive radiation events during Pleistocene climatic oscillations, or may result from recurrent episodes of reassembly of species of more ancient origin, to form current biota concomitant with climatic fluctuations. A calibrated phylogeny of one particularly species-rich insect genus (moths of the geometrid genus Eois) revealed that most speciation events in that clade of highly host-specific herbivores occurred in the Miocene; only very few splits extended into the Pleistocene. This temporal pattern of diversification mirrors major radiation phases in the principal host plant family (Piperaceae) of these moths. This hints to biotic interactions as driving force of adaptive speciation. Calibrated phylogenies from various other Andean organisms likewise give no indication of massive speciation fostered during Pleistocene climate fluctuations.