Paleontology of leaf beetles

`The rate of evolution in any large group is not uniform; there are periods of relatise stability, and periods of comparatively rapid change.' Cockerell and LeVeque, 1931 To Yenli Ych, my beloved wife, a most wonderful person! The fossil record of the Chrysomelidae can be tentatively traced back to the late Paleozoic to early Mesozoic Triassic. Mesozoic records at least 9 subfamilies, 19 genera, and 35 species, are represented by the Sagrinae, the exclusively Mesozoic Proto scelinae, Clytrinae, Cryptocephalinae, Eumolpinae, Chrysomelinae. Galerucinac, Alticinae, and Cassidinae. Cenozoic records at least 12 subfamilies- 63 % of the extant- 12! genera, and 325 species, include the same extant subfamilies as well as the Donaciinae, Zeugophorinae, Criocerinae, and Hispinae and can be frequently identified to genus, especially if preserved in amber. Quaternary records are often identified to extant species. tn total, at least t3! genera about 4 % of total extant, and 357 species < 1 % have been reported. At least, 24 genera <1 % of the extant seem to be extinct. Although reliable biological information associated with the fossil chrysomelids is very scarce, it seems that most of the modern host-plant associations were established, at least, in the late Mesozoic to early Cenozoic. As a whole, stasis seems to be the general rule of the chrysomelid fossil record. Together with other faunal elements, chrysomelids, especially donaciines, have been used as biogeographic and paleoclimatological indicators in the Holocene. I

Origins and diversification of subsociality in leaf beetles (Coleoptera: Chrysomelidae: Cassidinae: Chrysomelinae)

Leaf beetles (Chrysomelidae; ~40,000 species) are commonly solitary animals but subsociality, maternal care of broods, is known in Cassidinae and Chrysomelinae. We report 11 novel records from Brazil and Peru, bringing the number of subsocial chrysomelids to 35 species in 10 genera. Two evolutionary models of chrysomelid subsociality have been proposed. One proposed three independent origins within Chrysomelinae, based on the potential phylogenetic positions of subsocial genera. The other hypothesised that an evolutionary arms race between chrysomelid prey and their predators, parasites, and parasitoids has led to an escalation of defences. Using our phylogenies, we propose that subsociality originated independently in Cassidinae and Chrysomelinae, and several times within each subfamily. Subsociality was preceded by particular behaviours. In Cassidinae, exophagous larvae with chemically offensive faecal weaponry preceded aggregated living, group defences (e.g. cycloalexy), and maternal guarding. In Chrysomelinae, offensive glandular compounds preceded ovi- and viviparity before subsociality. © 2014 © 2014 Taylor & Francis.This study was supported by a NSF-EPSCoR grant #66928 (USA; CSC), by the Institut de Biologia Evolutiva (CSIC-UPF, Spain; JGZ), by the Centro Universitário de Lavras (Brazil; FFC), and by Stichting Bevordering van Natuurwetenschappelijk Onderzoek (Netherlands; RW).Peer Reviewe