Multigene phylogenetic analysis redefines dung beetles relationships and classification (Coleoptera: Scarabaeidae: Scarabaeinae)

Abstract

BackgroundDung beetles (subfamily Scarabaeinae) are popular model organisms in ecology and developmental biology, and for the last two decades they have experienced a systematics renaissance with the adoption of modern phylogenetic approaches. Within this period 16 key phylogenies and numerous additional studies with limited scope have been published, but higher-level relationships of this pivotal group of beetles remain contentious and current classifications contain many unnatural groupings. The present study provides a robust phylogenetic framework and a revised classification of dung beetles.ResultsWe assembled the so far largest molecular dataset for dung beetles using sequences of 8 gene regions and 547 terminals including the outgroup taxa. This dataset was analyzed using Bayesian, maximum likelihood and parsimony approaches. In order to test the sensitivity of results to different analytical treatments, we evaluated alternative partitioning schemes based on secondary structure, domains and codon position. We assessed substitution models adequacy using Bayesian framework and used these results to exclude partitions where substitution models did not adequately depict the processes that generated the data. We show that exclusion of partitions that failed the model adequacy evaluation has a potential to improve phylogenetic inference, but efficient implementation of this approach on large datasets is problematic and awaits development of new computationally advanced software. In the class Insecta it is uncommon for the results of molecular phylogenetic analysis to lead to substantial changes in classification. However, the results presented here are congruent with recent morphological studies and support the largest change in dung beetle systematics for the last 50 years. Here we propose the revision of the concepts for the tribes Deltochilini (Canthonini), Dichotomiini and Coprini; additionally, we redefine the tribe Sisyphini. We provide and illustrate synapomorphies and diagnostic characters supporting the new concepts to facilitate diagnosability of the redefined tribes. As a result of the proposed changes a large number of genera previously assigned to these tribes are now left outside the redefined tribes and are treated as incertae sedis.ConclusionsThe present study redefines dung beetles classification and gives new insight into their phylogeny. It has broad implications for the systematics as well as for various ecological and evolutionary analyses in dung beetles.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0822-x) contains supplementary material, which is available to authorized users.

Tropical dung beetle morphological traits predict functional traits and show intraspecific differences across land uses

“…Based on the high intraspecific variability detected in some morphological traits and the overlap between morphology and functional groups, we suggest that morphometric data be used as an additional tool to behavioral classifications of functional traits in dung beetles. Due to the lack of a resolved phylogeny for dung beetles (Monaghan et al., ; Tarasov & Dimitrov, ), it was not possible to control for the influence that phylogenetic relatedness could have on the morphology of the species studied. Despite this potential bias, the separation between functional groups is strong enough to suggest these patterns would remain if relatedness was accounted for.…”

Diversity of the dung beetles (Coleoptera: Scarabaeinae) in an altitudinal gradient in the east slope of los Andes, Napo province, Ecuador

“…Food preferences groups were defined by the percentage of individuals collected in each type of bait (dung: coprophages or carrion: necrophages): when the proportion of individuals was less than 75% of one of the two baits, the species was assigned to the generalists group. We decided not to include the information related to the taxonomic level of tribe for each genus because at the moment many Neotropical genera are without tribal affiliation [37].…”

Taxonomic review of theDichotomius mamillatusgroup (Coleoptera: Scarabaeidae), with a description of a new species,Dichotomius(Dichotomius)gandiniisp. nov., from western Amazonia

“…The study of the female genital organs was not included in this research because these structures are largely membranous (except for the spermatheca), thus apparently providing a limited number of informative characters to be used in taxonomic studies. For example, López‐Guerrero () and Rossini & Vaz‐de‐Mello () had difficulties separating species in the tribe Dichotomiini ( sensu Tarasov & Dimitrov ) using only female genital traits. Despite that, over the years, a significant number of researchers have considered the study of the female genitalia to be particularly informative for their taxonomic and phylogenetic investigations.…”

“…Over the years, multiple works on Scarabaeinae have provided evidence on the crucial role of endophallic lamellae in reconstructing convincing evolutionary scenarios (see, e.g. Tarasov & Génier and Tarasov & Dimitrov ) and providing robust characterisation of species boundaries. Basically, the importance of these structures should be attributed to their function.…”

“…Based on a comprehensive morphological and molecular study of the subfamily Scarabaeinae, Tarasov & Dimitrov () proposed the tribe Dichotomiini sensu novo ( nec Dichotomiini sensu Pereira, 1954) to accommodate the genus Dichotomius , along with Holocephalus Hope, , Chalcocopris Burmeister, and Isocopris Pereira & Martínez, . Dichotomius currently comprises about 170 species and subspecies (Schoolmeesters ), which are today included in the following four subgenera (Martínez ): Dichotomius s. str ., Homocanthonides Luederwaldt, , Luederwaldtinia Martínez, and Selenocopris Burmeister, .…”