Filogenia molecular, sistemática y evolución de los chrysomelinae australianos (coleoptera, chrysomelidae)

Abstract

Our knowledge about the natural history of the Australian fauna is still far from being complete. Australian insects are a case in which the majority of the species are yet to be described, and in many cases its origin remains unknown due in part to the lack of detailed phylogenetic studies. Among them are the leaf beetles in the subfamily Chrysomelinae. To date, ca. 750 Australian chrysomeline species have been described belonging to 43 genera, inhabiting disparate biomes. Their ecology is poorly understood, but the available information suggests that they are phytophagous species with a trophic spectrum restricted to few species of related plants. This work contributes to the knowledge of the systematics of the subfamily Chrysomelinae with special emphasis on Australian taxa through inferring phylogenetic hypotheses based on DNA sequences. The molecular phylogeny allows the establishment of a suprageneric classification system for the Chrysomelinae subfamily: Timarchini and Chrysomelini tribes. The tribe Chrysomelini can in turn be divided into several sub-tribes, including Chrysomelina, Doryphorina, Phyllocharitina, Entomoscelina and Gonioctenina. Our results also suggests the need for taxonomic reviews for the genera Callidemum, Chalcolampra, Chrysolina, Paropsisterna, Paropsides and Peltoschema. The origin of Australian lineages dates back to the Eocene. The evolutionary history of the Australian Chrysomelinae is related to their host plants: ancestral chrysomelines that fed on the incipient sclerophyllous vegetation in rainforest tracked their host plant lineages in the colonization of the new semi-arid environment after the contraction of their habitats. We also inquire into the processes that may have promoted the diversification of Chrysomelinae in Australia, using as a case study 15 Calomela species. We provide the first molecular phylogenetic hypothesis for the genus, which originated in the late Oligocene. Lineage diversification reflects a logistic density-dependent model. Useful morphological characters are identified. cox1 and ITS2 DNA sequences ensure unambiguous identification of the studied species. Finally, we propose an approach to infer phytophagous insects' diet from a phylogenetic perspective. The method is evaluated in 79 species (25 genera) of Australian Chrysomelinae, revealing their enormous trophic diversity and some evolutionary trends in their ecology.