Evolutionary history of the butterfly subfamily Satyrinae (Lepidoptera: Nymphalidae)

Abstract: I present an overview of the evolutionary history of Satyrinae butter?ies (Lepidoptera: Nymphalidae). By using Bayesian and cladistic methods, I develop a phylogenetic hypothesis as a basis for studying the evolutionary history of the group. After estimating ages of origin and diversi?cation for clades of interest, I show evidence for a radiation of a highly species-rich group of grass feeders in Satyrinae —the tribe Satyrini— which explains in part the high diversity of this group. The timing of diversi?cation for Satyrini butter?ies coincided with the spread of grasses throughout the globe, which was followed by spread of the butter?ies and colonization of new emerging habitats made available by the change in global climate during the Oligocene that facilitated the spread of grasses. Such a dispersal of Satyrinae was the result of a habitat shift from closed, forested environments into open, grasslands and savannas, which became increasinly common since the Oligocene. Such dispersal of Satyrinae was facilitated by the appearance of geographic bridges that permitted ancestral migrations from the Palaearctic into North America and from North to South America, such as the continuous forest belt of Beringia (at 31 Mya and 14–10 Mya) and the temporary GAARlandia landspan (during 35–33 Mya). Thus, I show that the Satyrinae butter?ies are such a highly diverse and distributed worldwide group of organisms thanks to many factors that were of crucial importance in their evolution. Intrisic factors such as evolution of adaptive traits and phylogenetic constrains, as well as exogenous contingencies such as climate change and geological events. Thus, in this thesis I show strong evidence that Satyrinae is so species-rich because they were able to feed on grasses, escape from living in dicotyledonous forests and start inhabiting grasslands and savannas.