Evolutionary Constraints in Hind Wing Shape in Chinese Dung Beetles (Coleoptera: Scarabaeinae)

Abstract

This study examines the evolution hindwing shape in Chinese dung beetle species using morphometric and phylogenetic analyses. Previous studies have analyzed the evolution of wing shape within a single or very few species, or by comparing only a few wing traits. No study has analyzed wing shape evolution of a large number of species, or quantitatively compared morphological variation of wings with proposed phylogenetic relationships. This study examines the morphological variation of hindwings based on 19 landmarks, 119 morphological characters, and 81 beetle species. Only one most parsimonious tree (MPT) was found based on 119 wing and body characters. To better understand the possible role of the hindwing in the evolution of Scarabaeinae, additional phylogenetic analyses were proposed based on the only body features (106 characters, wing characters excluded). Two MPT were found based on 106 body characters, and five nodes were collapsed in a strict consensus. There was a strong correlation between the morphometric tree and all phylogenetic trees (r>0.5). Reconstructions of the ancestral wing forms suggest that Scarabaeinae hindwing morphology has not changed substantially over time, but the morphological changes that do occur are focused at the base of the wing. These results suggest that flight has been important since the origin of Scarabaeinae, and that variation in hindwing morphology has been limited by functional constraints. Comparison of metric disparity values and relative evolutionary sequences among Scarabaeinae tribes suggest that the primitive dung beetles had relatively diverse hindwing morphologies, while advanced dung beetles have relatively similar wing morphologies. The strong correlation between the morphometric tree and phylogenetic trees suggest that hindwing features reflect the evolution of whole body morphology and that wing characters are suitable for the phylogenetic analyses. By integrating morphometric and cladistic approaches, this paper sheds new light on the evolution of dung beetle hind wings.

Phylogeny of the Oniticellini and Onthophagini dung beetles (Scarabaeidae, Scarabaeinae) from morphological evidence

“…In contrast to all other studies, Bai et al (2011) found the sisyphines positioned within the oniticellines. This study relied on hind wing and body morphological characters and the result is most likely due to evolutionary convergence.…”

“…But they may indeed not be onthophagines. In Bai et al (2011) using morphological evidence, they found Cassolus + Parachorius positioned outside the onthophagine clade. A recently described species of the Oriental canthonine Parachorius bridges the morphological gap between these two genera, and both form a monophyletic clade according to Tarasov and Keith (2011).…”

A cybertaxonomic revision of the new dung beetle tribe Parachoriini (Coleoptera: Scarabaeidae: Scarabaeinae) and its phylogenetic assessment using molecular and morphological data

“…Both molecular and morphological analyses converged in supporting monophyly of Parachorius + Cassolus with high support values (morphology: Bremer support value 3; molecules: 100% bootstrap support) that is consistent with the previous morphological analysis (Bai et al 2011). The morphological analysis (Fig.…”

“…A recent study found a new species representing a morphological link between the two genera and suggested a putative synonymy between Parachorius and Cassolus as well as their close affiliation with the New World genus Canthon Hoffmannsegg, 1817 (tribe Deltochilini). Further, the monophyly of the clade comprising species of Parachorius and Cassolus occurring in China was supported by the morphological phylogenetic analyses (Bai et al 2011). The taxonomic investigation of the museum specimens and additional recently-collected material of Cassolus and Parachorius from the Oriental Region revealed that a large portion of their species diversity is still undescribed.…”

Model organisms in evo-devo: promises and pitfalls of the comparative approach

“…For example, Bai et al (2011Bai et al ( , 2012 represent morphological variation of hind wings in Chinese species of true dung beetles (Scarabaeinae) by using these map-like models. Then, they compare this geometric morphometric data with proposed phylogenetic relationships, using the former to trace potential errors in the phylogenetic tree.…”