Contraction of the life cycle and the Evolution and Diversification of cave beetles

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Holometabolous insects represent more than 50% of the species in the animal kingdom. Their four main orders are Coleoptera, Hymenoptera, Diptera and Lepidoptera. Holometabolous insects are characterized by a peculiar life cycle including a larva radically differing from the adult in terms of ecology and morphoplogy. Holometabolous insects also have a pupa, thus complete metamorphosis. The complete metamorphosis is supposedly the main reason of the unequalled evolutionary success of the group. Presence of larval stages is then arguably an evolutionary key innovation fuelling lineage diversification. However, in few extreme cases, this strategy does not seem to be optimal and alternative strategies emerged, for example in some lineages that colonize the subterranean environment. There are some species where larval life is so strongly abbreviated that the hatched, non-feeding larva pupates immediately.Here we suggest to use highly diverse ground beetles (Carabidae: Trechini) and a comprehensive molecular phylogenetic framework to study the links between contraction of larval cycle and evolutionary success in hypogean environments. Our main research questions are: Where does a contracted life cycle occur? Are clades with contracted life cycle significantly more diverse than clades with normal larval development and does a strongly derived ontogeny therefore represent a launching pad or key innovation for diversification in certain clades of underground beetles?