Molecular phylogenetics of Australian weevils (Coleoptera: Curculionoidea): exploring relationships in a hyperdiverse lineage through comparison of independent analyses

Abstract

With over 60 000 described species in approximately 5800 genera, weevils (Curculionoidea) represent one of the most diverse and species‐rich superfamilies of eukaryotes on the planet. Recent attempts to resolve the phylogeny of family‐group taxa in weevils using morphological, molecular or combined data sets have produced vastly different patterns of relationships, particularly within the largest family, Curculionidae. Here we present an estimation of the phylogeny of Australian weevils and of the divergence dates of the major lineages based on a multi‐gene data set (28S, 16S and COI) spanning ∼3.5 kbp of DNA sequence. We assess its topological similarities to, and differences from, other recently published phylogenetic trees, particularly in relation to taxon sampling and relative diversity of the lineages, and we discuss the implications for weevil systematics. Our results, derived from a different set of taxa that has different combination of loci and different fossil calibration points, recover a number of relationships and age estimates that are congruent with those obtained by other recent weevil phylogeny estimates, indicating that we are beginning to recognise the major monophyletic lineages and reconstruct the major diversification events within Curculionoidea. Resolution of natural groups within families (e.g. subfamilies and tribes) however remains poor, even for studies with the largest volume of sequence data (whole mitochondrial genome analyses), evidently largely due to deficient taxon sampling. Although taxon sampling is known to be one of the most critical determinants of accurate phylogenetic reconstruction, it is rarely addressed in phylogenetic assessments. Our case study of weevils highlights not only its importance, but also the fact that it is very difficult to achieve comprehensive representative sampling in hyperdiverse lineages because of their sheer taxic diversity. Doubts concerning the monophyly of many subordinate lineages exacerbate this problem, restricting the use of exemplar approaches to taxon sampling. The value of comparing different data sets and analyses for assessing systematic relationships is often overlooked, even despite the presence of many conflicting results in previous phylogenetic hypotheses. A summary of relationships recovered relative to taxon sampling and methodological differences between different phylogenetic reconstructions provides an important stepping‐stone in understanding the diversification of weevils.

Weevils as Targets for Biological Control, and the Importance of Taxonomy and Phylogeny for Efficacy and Biosafety

“…All recent molecular phylogenetic analyses [13][14][15][16][53][54][55]] recovered a close relationship between Hyperinae and Entiminae, although taxon sampling was too small and patchy in all of them to properly elucidate this relationship. Both Hypera (Hyperini or Hyperinae) and Sitona have usually been recovered in basal positions in relation to Entiminae, either separate from each other [55] or in some clade together [14,15,53], although in the analysis of McKenna et al [54] both genera appeared bedded inside different, mixed clades of Entiminae and Cyclominae and in that of Gunter et al [13] the three Australian genera of Hyperinae (Hypera not included) clustered with the genus Steriphus Erichson (Cyclominae: Listroderini) in some analyses, whereas Sitona grouped separately on a long branch. Strong support for a position of Hypera (Hyperinae) as sister-group of Entiminae + Cyclominae was found by Shin et al [16], but their analysis did not include Sitona nor a sufficient number of other Entiminae, Hyperinae and Cyclominae to resolve the exact relationships between Sitona and Hypera and between Entiminae and Hyperinae overall.…”

“…Recent molecular techniques in combination with analyses of morphological characters have increasingly helped to clarify some of these quandaries and have mostly confirmed Kuschel's proposed 6-7 main weevil lineages as based only on morphology [12]. In the large family Curculionidae, however, phylogenetic relations still remain largely unresolved [13][14][15][16].…”

Molecular phylogeny of bark and ambrosia beetles (Curculionidae: Scolytinae) based on 18 molecular markers

“…Previous attempts on investigating phylogenetic relationships in beetles have demonstrated recurrent problems in resolving deeper relationships such as those between the four beetle suborders, but also much younger divergences [1][2][3][4]. One of the most problematic groups includes the weevils, where the majority of tribes and subfamilies remain unresolved despite considerable efforts in assembling molecular data [5][6][7][8]. Bark and ambrosia beetles in the subfamily Scolytinae represent a weevil lineage where much effort has been invested in developing molecular markers for phylogenetic analysis [9,10].…”

A Review of the Tribe Cryptoplini (Coleoptera: Curculioninae), with Revision of the Genus Menechirus Hartmann, 1901 and Description of a New Genus Associated with Macadamia

“…This type of penis, consisting of distinct ventral and dorsal parts, respectively the pedon and tectum, is characteristic of the more basal families of weevils (Nemonychidae to Brentidae) as well as of the basal lineages of Curculionidae (Brachycerinae-Erirhininae), whereas the 'higher' Curculionidae (the CEGH and CCCMS clades [35]) have a pedal type of penis, without a tectum. There are other differences between these two types of male genitalia in weevils too, concerning the structure of the temones and the tegmen as well as of the sternites VIII and IX associated with the aedeagus.…”